HYGIENE OF SOIL AND AIR.

 METHOD OF HYGIENIC nESTIMATION OF THE SOIL FROM DATA OF SANITARY INSPECTION OF AREA AND BY RESULT nOF LABORATORY ANALYSES OF THE TEST.

 CLEANING OF INHABITED nPLACES.

METHOD nOF DETERMINATION OF CONCENTRATION OF СО₂ IN THE AIR AS INDEXES OF ANTROPOGENIC CONTAMINATION OF AIR AND nVENTILATION OF APARTMENTS. CONCEPT ABOUT AN AIR CUBE, NECESSARY AND ACTUAL nVOLUME AND DIFFERENT nTYPES OF nVENTILATION, THEIR SCIENTIFIC GROUNDING.

Soil may be ndefined as the fine earth ncovering land surfaces that has nthe important function of serving nas a substratum of plain, animal, nand human life. Soil acts nas a reservoir of nutrients and nwater and absorbs and oxidises nthe injurious waste substances that plant growth naccumulates in the rhizosphere (i.e.. the root nzone). These functions of soil nare possible because it contains nclay minerals and organic substances n(clay and humus form the nfiner part of soil) that nabsorb both ions (electrically charged atoms) and water.

                                                       

Average Composition of Soil

Soils are composed of mineral matter, air, water, organic matter, and norganisms. There are two general types of soils, mineral soils and organic nsoils. Mineral soils form from decomposed rocks or sediment derived from rocks. nOrganic soils form from the accumulation of plant material, usually iwater-saturated, anaerobic conditions that retard decomposition. Mineral matter nis described as texture and comprises half the volume of mineral soils. The nother half of the soil volume is composed of voids or holes. These voids fill nwith water as the soil soaks up rain or flood waters, then are displaced with nair as the water drains away, evaporates, or is absorbed by roots.

Both plants nand animals help to create a soil. As they die, organic matter incorporates nwith the weathered parent material and becomes part of the soil.

  Living nanimals such as moles, earthworms, bacteria, fungi and nematodes are all busy nmoving through or digesting food found in the soil. All of these actions mix nand enrich the soil. Here is a creature from each major group of soil norganisms.

There are many functions nprovided by soil that are nimportant to human beings. Agriculture nand animal husbandry produce more than 90 percent nof the human npopu­lation’s food supply: together with forestry these nactivities connected with soil produce nmany oilier materials needed by human beings, nsuch as wood, ncellulose, textile fibres, and leather. nThe utilisation of soil by nagriculture, animal husbandry, and forestry is often ntermed “soil exploita­tion.” Soil is necessary for ndwellings, highways, airports, and recreation nareas, and it also provides nroad fill and material for nwater retention structures and fulfills many other nessential functions.

 

These horizons collectively are known as a nsoil profile.

The uppermost is called the organic horizon or nO horizon. It consists of detritus, leaf litter and other organic material nlying on the surface of the soil. This layer is dark because of the decompositiothat is occurring.

  Below nis the A horizon or topsoil. Usually it is darker than lower layers, loose and ncrumbly with varying amounts of organic matter. This is generally the most nproductive layer of the soil.

  The next layer is the B horizon or subsoil. Subsoils are usually lighter in color, dense and low iorganic matter. Most of nthe materials leached from the A horizon stops in this zone. Still deeper is nthe C horizon. It is a transition area between soil and parent material. At some point the C horizon will give up to the nfinal horizon, bedrock.    

Basic physical properties and texture of nsoil

 

Lithosphere (the earth’s crust) – mineral nand organic covering of the Earth, which nextends from its surface to magma. It consists of lithosphere itself, which is formed from magma rocks destroyed by physical, physicochemical nand chemical processes before beginnings nof life on Earth, and soil.

Soil is a nsurface layer of lithosphere (from few millimeters in mountains and up to 10 kilometers in lowlands), nwhich was formed after beginnings nof life on Earth as nthe result of climate, flora and life (microorganisms nand roots of higher plants) influence. Soil consists of the surface or fertile layer n(0-25 cm) or humus layer, which is characterized by fertility nand which is cultivated at growing plants, and of soil nitself.

Soils are very different depending non conditions of their formation, first of all on climate nand flora. In Ukraine most common are chernozem n(black earth soils) (54.0% of territory), nthen –– grey forest nsoils (18.2% of nterritory) and sod-podsol soils (7.8% nof territory).

 

Basic nphysical properties of soil:

– texture – percentage nof soil particles according to their sizes. It nis determined by screening through Knopf nsieves. There are 7 types (called “numbers”) nof such sieves with apertures of different ndiameters from 0.25 to 10.0mm (fig. n18.1). Soil texture consists of the following elements: stones and gravel (size n> 3 mm); coarse sand (3-1 mm), medium (1-0.25mm), nfine (0.25-0.05 mm); coarse ndust (0.05-0.01 mm), medium (0.01-0.005mm), nfine (0.005-0.001mm); nsilt (< 0.001 mm). According to texture, soils are classified based on specific nweight of physical sand (particles of nsize > 0.01 mm) and nof physical clays (particles of size n< 0.01 mm).  (Appendix n3);

– porosity n– total volume of npores in the unit of soil volume, which is expressed in percents. The bigger is the size of some elements nof soil tissue, i.e. its granularity, the bigger is nthe size of pores in homogeneous soil. The biggest pores are in rocky soil, smaller nones are in sandy soil, very small npores are in clay soil, and the smallest ones – in peat nsoil. At that total volume of pores, expressed in percents, increases, i.e. soil porosity is as higher as smaller is the size of some elements nof soil tissue. Thus, porosity of sandy soil is 40%, and peat soil – 82%;

Fig. Knopf sieves for nsoil texture analysis

– air permeability – soil ability nto let air through its thickness. It increases nwhen size of pores is bigger and doesn’t depend on their total volume n(porosity);

– water permeability – soil ability to absorb nsurface water and to let it npass through. Permeability nconsists of two stages: imbibition, when free pores gradually get nfilled with water till total saturation of nsoil and filtration, when, nin the result of total water saturation of soil, water starts moving in soil npores because of gravity;

– moisture capacity – amount of moisture, which soil is capable to retain due to sorptive and capillar powers. The smaller is nthe size of pores and the bigger is their total volume, i. e. nporosity – the bigger is the moisture capacity. The finer is soil texture, the higher is nits moisture capacity;

– soil capillarity – nsoil ability to lift water via capillaries from the bottom nlayers up. The smaller is the size of soil texture particles n- the bigger is soil capillarity, but isuch soil water goes up higher and slower.

In soils of light texture (sandy, clay sandy, light nloamy) compared to heavy soils (clays, heavy loams) physical sand prevails, pores are of the larger size, porosity isn’t high, air and nwater permeability, filtration capacity are considerable, capillarity and nmoisture capacity are low. On the one hand, processes of soil bio-decontamination run rather quickly in such soils, on the other hand, migration of chemical substances from soil into ground nand surface water reservoirs, ambient air and plants is more considerable.

Properties nof soil particle size

 

Soil consists of biotic (soil nmicroorganisms) and abiotic ncomponents. Abiotic components include hard substance nof soil (mineral and organic compounds and organomineral complexes), soil nmoisture and soil air.

60––80% of mineral (non-organic) substances of soil are nrepresented by crystalline silica or quartz. The nimportant place among mineral compounds is occupied by alumina-silicates, i.e. nfeldspar and mica. Also to alumina–silicates belong secondary clayey minerals, i.e. of montmorilonite group (montmorilonite, notronite, beidelite, saconite, hectorite, stevensite). nTheir hygienic importance is nthem being the cause of absorbing capacity and volume nof cations’ absorptio(i.e. heavy metals) by soil.

Beside silica and alumina–silicates, almost all elements of Mendeleyev’s table appear in mineral compound of soil.

Organic substances of soil are represented both by soil organic (humic acids, fulvic acids etc.) compounds, which nare created by soil microorganisms and which are called humus, and nby strange for soil organic substances, which came into the soil from outside nin the result of natural processes and technogenic n(anthropogenic) pollution.

Soil moisture can be both in solid and liquid forms, and in the nform of vapour. From hygienic point of view of the most interesting is liquid moisture, which can be in forms of: n1) hygroscopic water, which is condensed on the surface of the soil particles; n2) membranous water, which remains on the surface of soil particles; n3) capillary water, which is kept nby capillary forces in thin pores of soil; 4) gravity nfree water, which is influenced by gravity nor hydraulic head and fills in soil big pores.

Soil air is a mixture of gases and vapour, which fills nin soil pores. According to its composition it differs from atmosphere air and constantly interacts with it by diffusioand concentration gradient. Soil air and water oppose nto each other in respect of space in pores. Natural compound of soil air is controlled by oxygen utilization rate and carbon dioxide generatioas the result of microbiological processes of mineralization of organic nsubstances. With growth nof depth content of carbon dioxide in soil nair increases and oxygen content – decreases.

Hygienic nsignificance of soil

Soil is:

– the medium, where processes of transformation and soil energy accumulatiotake place;

– leading member of turnover in nature, nthe medium, in which different complicated processes of destruction and synthesis of organic substances take place ncontinuously;

– main element of biosphere, where processes of migration, transformation and metabolism of all chemical substances both of natural and anthropogenic n(technogenic) origin take place. Migration takes place both in short (soil n–– plant –– soil, soil n–– water –– soil, soil n–– air –– soil) and long (soil n–– plant –– animal –– soil, soil n–– water –– plant –– soil, soil n–– water –– plant –– animal n–– soil, soil –– air n–– water –– plant –– animal n–– soil etc.) migration chains;

– forms the chemical structure of foodstuffs of nvegetable and animal origin;

– plays an important role in formation of water quality of nsurface and ground sources of domestic and drinking water-supply;

– affects nqualitative structure of contemporary atmosphere;

– of endemic importance – nanomalous natural chemical structure of soil in endemic provinces is a reason of rise and local spreading of endemic diseases (geochemical endemic diseases): nendemic fluorosis and caries, endemic goiter, foot-and-mouth ndisease (FMD), molybdenum gout, endemic nosteoarthritis or Kashin-Beck disease, endemic cardiomyopathy (Keshan’s ndisease), selenosis, boric nenteritis, endemic nephropathy etc.;

– of epidemic importance – nit can be a transmission factor of pathogens of infection diseases and invasions to people: enteric infections of bacterial (typhoid, paratyphoids А and В, bacillary dysentery, cholera, coli-entheritis), viral (virus A hepatitis, enterovirus infections: poliomyelitis, Coxsackie virus infection, ЕСНО) and protozoa ethiology (amebiasis, lambliosis); zooanthroponosis (types of leptospirosis: infectious jaundice or Vasyl’yev – nVail disease, anicteric leptospirosis, nbrucellosis, tularemia, anthrax); mycobacteria nof tuberculosis; spore-forming clostridia – pathogens nof tetanus, gas gangrene, botulism; geohelminthosis n– ascaridiasis, trichocephalosis, ankylostomiasis.

– the nplace for liquid and soil domestic nand industrial waste disposal due to natural npurification processes (soil nsanitary significance). Soil natural purification is characterized by presence of saprophytic decomposers, nitrifying nand nitrofying bacteria, elemental organisms, larvae, worms, fungi, viruses, coliphages and by nits physical–and–chemical properties. It consists in soil capability to transform organic compounds into mineral substances good for plants’ assimilation:  carbohydrates – into water and carbon dioxide; fats– ninto glycerin and nfatty acids and then – nalso into water and carbon dioxide; nproteins – into amino acids with nammonia and ammonia salts evolvement and their further oxidation to nitrites nand nitrates; protein sulfur – ninto hydrogen sulfide etc.

Methods of land parcel sanitary inspection and soil sampling

Sanitary inspectioof the land parcel includes:

– definition of ground assignment (territory of a hospital, npreschool institutions, schools, industrial nenterprises, objects of waste disposal of ndomestic, industrial, construction origin, etc);

– visual inspection of the parcel, determination of character nand location of sources of nsoil pollution (distance), nrelief, drain direction of precipitation waters, flow ndirection of ground waters;

– determination nof soil texture n(sand , clay sand, loamy soil, chernozem);

– determination of points for soil sampling for analysis: places near the source of pollution and near ntest area of known cleasoil (at a distance of this source).

Samples are taken by “envelope” ntechnique on nrectangular or square areas of 10×20 nmeters or more. In each of five sampling points of nthe “envelope” 1 kg of soil is taken from the depth of 20 cm for samples. Aaverage sample of 1 kg nmass is prepared from taken samples.

 

Each taken sample is accompanied by a covering letter, which includes information about place, address and assignment of the parcel, soil type, relief, ditch level of subterranean waters, goal and volume of the analysis, inspection results received at the place, date nand time of sampling, weather of previous 4-5 ndays, who took a sample, his nsignature. Samples are packed into closed nglassware and polyethylene nbags.

When

Soil samples nmay be taken at any time during the year when soil conditions permit.  The nsoil should not be too wet or muddy as it will dry as hard as a rock and may be ndifficult to mix.

 

Where

If the area nis fairly level and the soil appears to be uniform, collect 5 samples and mix ntogether to form a composite sample.

If your lawor garden has large areas which differ in fertility, take one composite sample nfrom each area.   For example, you may want to sample the back veggie ngarden (A composite sample from 5 sub-samples labeled A) and from the front nlawn ( a composite of 5 sub-samples labeled B).(see ndiagram below).  If you are fertilizing these areas differently it makes nsense to take two different samples for soil testing because.

How?

It is best to nuse a soil sampler which samples uniformly to the depth you want.  You cado this with a garden trowel if you are careful  to nget a uniform about in each sample to the depth of 15 cm or 6 inches.

 

Criteria of soil sanitary state

 

All indices are divided into direct (allow to assess the level of soil contamination and level of danger for population health directly from the results of laboratory analysis of taken samples and indirect (allow to ndraw a conclusion of the existence of nsoil contamination, its prescription and duration by ncomparison of the results of soil laboratory analysis with test clean soil of nthe same type, which was taken as a sample from non-contaminated areas).

Sanitary number of Khlebnikoff – nis a ratio of humus nitrogen (pure soil organic substance) to total organic nitrogen (consists of humus nitrogen and nitrogen of strange nfor soil organic substances that contaminate nit). If soil is pure, sanitary nnumber of Khlebnikoff equals to n0.98-1.

Soil coli–titer – nis a minimal amount of soil in grammas, in which one bacteria of colibacillus group is nfound.

Soil anaerobe titer (perfingens–titer) – is a minimal amount of wastes in grammas, in which an anaerobic clostridia nis found.

Soil microbial number – is a number of microorganisms in one gram of soil that grew up on 1.5% beef-extract agar at temperature 37⁰С during 24 hours.

 

Soil classification according to texture (according nto N.А. Kachinskiy)           

n

Names of soils according to texture	Content of particles, %
	Clay particles of a diameter smaller than 0.01 mm	Sand particles of a diameter larger than 0.01 mm
Heavy clay soils	larger than 80	smaller than 20
Clay soils	from 80 to 50	from 20 to 50
Heavy loamy soil	from 50 to 40	from 50 to 60
Medium loamy soil	from 40 to 30	from 60 to 70
Light loamy soil	from 30 to 20	from 70 to 80
Clay sands	from 20 to 10	from 80 to 90
Sandy	from 10 to 5	from 90 to 95
Light sandy	smaller than 5	larger than 95

Filtratiocapability of soils of different texture

 

 

 

 

Technique of hygienic assessment of sanitary state of soil

When drawing a report on hygienic assessment of sanitary condition of soil it is reasonable to use a scheme n(algorithm) that provides for the following 6 stages:

І –  goal and task are determined. Thus it is necessary to state a hygienic value of sanitary condition of natural soil at the time of the assignment of the parcel nfor new settlement construction. During the regular sanitary inspection it is necessary to assess the sanitary condition of artificially created soil on the ground areas for residential and public building, playgrounds for children and sport ngrounds. When the nepidemic situation is unfavorable, it is necessary to find out if soil is a factor in spreading pathogenic microorganisms. Sometimes, nwhen investigating cases of acute and chronic poisonings it’s necessary to determine the level of soil contamination by ntoxic chemical substances (pesticides, heavy metals etc.). Sanitary condition of soil may be studied in order to assess nthe efficiency of sanitary purification of the settlement nterritory, during the regular sanitary inspection of nsewage disposal plant and facilities of utilization and nextermination of SDW in order of assessment of their work nefficiency.

II – according to set tasks a required extent of examinations is set. nThus, during the hygienic assessment of natural soil of the ground areas nassigned for new settlement construction, complete nsanitary analysis of every index of sanitary condition is required. During the nhygienic assessment of artificially created soil of settlements, in case of nfavorable epidemic situation, it is reasonable to carry out examinations by sanitary nanalysis reduced scheme: determination of total and hygroscopic moisture, Khlebnikoff’s sanitary number, chlorides, soil noxidation, microbial number, titer of coli-group bacteria, anaerobe titer, nnumber of eggs of helminthes, number of larvae and chrysalides of flies. Icase of unfavorable epidemic situation it is important to include tests opresence of pathogenic bacteria and viruses into reduced sanitary analysis. nWhen investigating cases of acute and chronic npoisonings for the assessment of the level of soil contamination by chemical npoisonous substances it is sufficient to determine texture of soil, total and nhygroscopic moisture and content of hazardous substances: pesticides, nheavy metals, arsenic etc.

III – completeness of presented materials and availability of sanitary nexamination data are controlled, soil sampling schemes, methods of their npreliminary analysis, time constraints of analysis, soil samples’ keeping are nassessed, availability of soil laboratory analysis results in accordance to the nrequired research program are controlled.

IV – sanitary examination results are analyzed: а) sanitary–topographical characteristic nof the area; nb) sanitary-technical characteristic of the objects that ninfluence condition of the area; c) sanitary-epidemic situation. Preliminary conclusion concerning grounds for suspicion that soil can be contaminated by exogenic chemical substances or being a factor of spreading infections is drawn.

V – laboratory results nof soil analysis are assessed according to all data, that are required nby examination program. According nto indirect indices based on comparing the examined and test (“pure”) soil one, conclusion about the nfact of existence, prescription and durability of contaminatiois drawn. According to direct indices, based on sanitary assessment of the condition of soil (Appendices n4, 5), level of soil contamination and stage of its danger nfor the population health is assessed.

VI – general conclusion about sanitary condition of soil, nstage of its contamination and danger for the populatiohealth is drawn, nfuture soil pollution effect on population health depending on its levels is forecasted n(Appendix 6), preventive measures of  further ndeterioration of sanitary state of soil and ways of its improvement nare offered.

SOIL nPOLLUTION

Soil pollution nis usually a consequence of insanitary habits, various agricultural practices, nand incorrect methods of disposal of solid and liquid wastes, but can also nresult from fallout from atmospheric pollution. It is closely linked with the nultimate fate of those substances that are unlikely to undergo the natural nrecycling processes to which putrescible matter is nsubject. In industrialized countries, soil pollution is associated mainly with:

(1) The use of chemicals, such as fertilizers and growth-regulating nagents, in agriculture;

(2) the dumping on land of large masses of nwaste materials from the mining of coal and minerals and the smelting of nmetals.   Toxic or harmful substances cabe leached out of such materials and enter the soil;

(3)          nThe dumping on land of domestic refuse and solids resulting from the treatment nof sewage and industrial wastes.

(4)          The soil is thus becoming increasingly polluted with nchemicals, including heavy metals and products of the petroleum industry, which ncan reach the food chain, surface water, or ground water, and ultimately be ningested by man.

 

Imany countries of the world, and particularly in the developing ones, soil npollution with pathogenic microorganisms is still of major importance. In such ncountries, intestinal parasites constitute the most important soil pollutioproblem, as a result both of the improper disposal of nhuman excreta, waste water, and solid wastes, and of incorrect agricultural npractices. Thus it is estimated that about one-third of the world’s popula­tiois infected by hookworm, while one out of every four people in the world may be ninfected with Ascaris lumbricoides.

Soil Pollution by Biological Disease Agents

Biological nagents that can pollute the soil and cause disease in man can be divided into nthree groups:

(1) npathogenic organisms excreted by man and transmitted nto man by direct contact with contaminated soil or by the consumption of fruit nor vegetables grown in contaminated soil (man-soil-man);

(2)   pathogenic norganisms of animals, transmitted to man by direct contact with soil ncontaminated by the wastes of infected animals (animal-soil-man); and

(3)   pathogenic norganisms found naturally in soil and transmitted to man by contact with ncontaminated soil (soil-man).

Man-soil-man

Enteric bacteria and protozoa

Enteric nbacteria and protozoa can contaminate the soil as a result of: (a) insanitary nexcreta disposal practices; or (b) the nuse of night soil or sewage sludge as a fertilizer, or the direct irrigation of nagricultural crops with sewage. Soil and crops can become contaminated with the nbacterial agents of cholera, salmonellosis, bacillary ndysentery (shigellosis) and typhoid and paratyphoid fever, or with the nprotozoan agent of amoebiasis. However, these diseases nare most often water-borne, and transmitted by direct person-to-person contact, nor by the contamination of food. Flies that breed in, or come into contact nwith, faecal-contaminated soil can serve as nmechanical carriers of disease organisms.

Parasitic worms (helminthes)

Soil-transmitted nparasitic worms or geo-helminthes are characterized by the fact that their eggs nor larvae become infective after a period of incubation in the soil.

Animal-soil-man

In a number of zoonoses n(diseases of animals transmissible to man), the soil may play a major part itransmitting the infective agent from animal to man.

Leptospirosis

This ndisease affects both animals and man in all parts of the world. The nepidemiology of the disease follows a characteristic pattern similar to that of nother zoonoses, namely animal to animal, and animal nto man. In some areas, sheep, goats, and horses become infected. Rodent ncarriers include rats, mice, and voles. The dispersion of leptospires nis associated with specific environmental condi­tions, particularly those that nbring animal carriers, water, mud, and man together. Animal carriers ofteexcrete a profusion of leptospires—up nto 100 million per ml—in the urine. If this is excreted into water or mud that nis neutral or slightly alkaline, the leptospires may nsurvive for weeks. Susceptible animals and man entering this environment are nexposed to the agent and may develop infection varying from an inapparent reaction to an acute fulminating fatal disease. Leptospires usually enter the body through the mucous nmembranes or broken or macerated skin. Agricultural workers in irrigated fields, and in rice and cane fields in particular, oftebecome infected.

Anthrax

The nnumber of reported cases of anthrax in man is relatively small compared with nthe figures for other zoonoses; nevertheless, anthrax nis still of importance both as a human disease and because of its economic nimpact on animal husbandry. The spores of Bacillus nanthracis are very resistant to chemical and nenvironmental influences and can survive for years in certain soils as well as nin animal products, such as hides, hair, and wool. When anthrax infections ilivestock become established in a district, a relatively permanent enzootic nfocus of infection is created because of the long period for which the spores ncan remain viable in the soil.

Other diseases

Among nother diseases that follow the sequence animal-soil-man, mention should be made nof the following: visceral larva migrans, due mainly nto Toxocara canis, listeriosis, Clostridium nperfringens infections, lymphocytic choriomeningitis, South Americatypes of haemorrhagic fever, tuberculosis, salmonellosis, and tularaemia. nAlthough most of these diseases and infections are transmitted predominantly by ndirect animal-man contact, or through the ncontamination of food by animal droppings and wastes, soil pollution may also nplay an important part.

Soil-man

Mycoses

Fungi nand actinomycetes that grow normally as saprophytes nin soil or vegetation cause most of the serious subcutaneous, deep-seated and nsystemic mycoses. Under certain circumstances, however, they become pathogenic nand invade specific tissues or entire systems.

Tetanus

Tetanus nis an acute disease of man induced by the toxin of the tetanus bacillus growing nanaerobically at the site of an injury. The organism nhas a world-wide distribution, though cases of the disease are comparatively ninfrequent today. The infectious agent, Clostridium ntetani, is excreted by infected animals, nespecially horses. The imme­diate source of infection may be soil, dust, or nanimal and human faeces.

Botulism

This nis a frequently fatal type of poisoning caused by bacterial toxins produced by Clostridium botulinum. nThe reservoir of the organism is soil and the intestinal tract of animals. nThe toxin is formed by the anaerobic growth of spores in food, which is the nimmediate source of poisoning. The disease is usually transmitted by the ningestion, without previous cooking, of food from jars or cans imperfectly nsterilized during canning, the canned or preserved food having been infected nwith soil contaminated by Cl. Botulinum.

Soil Pollution and Solid Wastes Disposal nUrban areas

The nland serves as a major repository for the solid wastes of urban and industrial nareas. Solid wastes disposal in metropolitan areas has a number of public nhealth implications.

The nproblem of greatest concern stems from the fact that, with increasing nurbanization and the consequent increase in the area occupied by buildings, the nland available for depositing wastes is correspondingly reduced.

Ihighly industrialized countries, even the solid wastes from agriculture cabecome a problem, particularly when livestock and poultry wastes near urban centres become a breeding ground for flies and cause a nserious odour nuisance on decomposition.

Productioper head of solid wastes varies considerably from country to country, but with nrising living standards the amount of refuse produced is everywhere on the nincrease. In the USA nand some European countries this increase is estimated at about 3 % per year by volume, and 2 % per year nby weight.

The nproblems of land pollution by wastes differ in a number of import­ant respects nfrom those of water or air pollution, since the polluting material remains iplace for relatively long periods of time unless removed, burned, washed away, nor otherwise destroyed.

Imany of the more developed countries, aesthetic considerations have become nimportant in wastes disposal and there is less readiness to accept unsightly, nopen refuse dumps and junk heaps as an inevitable blot on the landscape. nInsects and rodents, which breed in such dumps, and odours nfrom decomposing organic matter or from slow smouldering nfires, can cause severe nuisance and public health problems.

With nthe increasing utilization of land for urban development, pressure to dispose nof solid wastes by methods other than land disposal has led to new pollutioproblems. Improper incineration can lead to severe air pollution, while ndischarge into water leads to overloading of treatment facilities and to increased npollution in already heavily burdened watercourses.

Agricultural land pollution

Ithe past, nutrient materials in the agricultural economy followed a clearly ndefined cycle: from the land to plants, from plants to animals, and then back to nthe land again. In some of the more highly industrialized countries, the use of nchemical fertilizers has short-circuited this cycle, and many agricultural nareas now have large surpluses of plant and animal wastes that, unless properly ndisposed of, can cause soil pollution. The problem becomes particularly severe nwhere urban areas border on agri­cultural land. In these fringe areas, nagricultural solid wastes may ulti­mately have to be handled in the same way as nurban wastes.

As nagriculture becomes more intensive, so that increasing quantities of synthetic nmaterials, such as pesticides, nutrients, and control agents, are used, chemical soil pollution coupled with increasing namounts of excess organic waste materials leads ultimately to severe land npollution problems in agricultural areas.

Contamination of the Soil by Toxic nChemicals

Agricultural chemicals

Fertilizers nare intended to fortify the soil for the raising of crops, but incidentally may ncontaminate the soil with their impurities. Irrigation of farmlands and norchards may do this if the source of water is polluted by industrial wastes nthat contain synthetic organic chemicals. During the last few decades, nherbicides, insecticides, fungicides, soil conditioners, and fumigants have nproduced intentional alterations of agricultural, horticul­tural, and silvicultural soils. The chemicals used may pollute the nsoil water.

Solid wastes from industry

Leach nate from industrial solid wastes may contain poisonous chemicals in solution; nthese may be concentrated iature by various organisms in the human food nchain.

A nrecent study has shown that the disposal of industrial solid wastes constitutes na major source of land pollution by toxic chemicals. It has been estimated that nsome 50 % or more of the raw materials used by industry ultimately become waste nproducts, and that about 15 % can be considered deleterious or toxic. In the United Kingdom, nclose to one million tons of materials classified as flammable, acid, caustic, nor indisputably toxic are dumped annually by industry. This amounts to about 20 kg per person per year. A nmajor portion of these wastes is dumped on the land either by private ncontractors or by arrangement with local authorities. Some wastes are dumped at nsea or incinerated.

These nwastes have, in certain instances, given rise to severe problems of soil npollution, either by poisoning the soil or crops, or by eventual entry into nground-water and surface-water sources.

Radioactive materials

Radioactive nmaterials can reach the soil and accumulate there, either from atmospheric nfallout from nuclear explosions, or from the release of liquid or solid nradioactive wastes produced by industrial or research establishments. The two nmost important radionuclides with long half-lives nproduced by nuclear fission are ‘”Sr (half-life n28 years) and ¹³⁷Cs (half-life 30 years). Fallout of relatively nrecent origin and discharges from nuclear reactors also contain a number of nother radionuclides of importance from the ecological npoint of view, e.g., ¹³¹I, ^u°Ba n+ ¹⁴⁰La, ¹⁰⁶Ru + ¹⁰⁶Rh, ¹⁴⁴Ce + ¹⁴⁴Pr, netc.

Levels nof radiation from fission products deposited in the soil by fallout in the nnorthern hemisphere are about 10-30 % of those due to natural radioactive nsubstances in the soil. Many authorities feel that there is very little evidence nto date to show that this increase in radiation levels could affect soil fauna nor their predators, but increased radioactive fallout could in time result ilevels of soil contamination high enough to cause concern.

Pollution of the land by the biological nagents of disease remains one of the major causes of debilitating infections ithe rural and semi-rural areas inhabited by the majority of the world’s npopulation. Land pollution by toxic chemicals from agriculture and industry, nleading to the contamina­tion of soil, food, and water, may prove to be a nsignificant hazard to health in the more industrialized areas of the world. The nproblems arising from the dumping on land of the ever-increasing amounts of ndomestic and indus­trial solid wastes will become more acute as world npopulation and the degree of urbanization increase.

Mechanic content of soil and it’s hygienic meaning

Sanitary condition of soil depends ngreatly on its structure.

  Soil consists of dense, liquid, gas and alive components. Soil solution is water with solved gases, nmineral and organic compounds. The types of soil liquid component are film, ncapillary and gravitation water. Dense component consists of mineral compounds nand humus – biogenic heavy-molecular dark colored soil (humine nacids, humane and ulmine). Gas components ratio ndepends on amount of pores and the sanitary condition of soil. Soil microflore, plants and animals inhabiting depends oclimatic and geologic conditions.

  Mechanic analysis data make navailable the following divisions of soils: stony, gravel, cartilage, sandy n(>80% sand and <10% of clay); sandy loam soil (50-80% of clay), lesser nloamy soil (30-50% of clay), loamy soils (50-80% of clay), clay soils (>80% nof clay), lime soils (>80% of clay), chalk soils, lessic nsoils (mixture of small sand particles with lime clay), black earth (>20% of nhumus), turf soils etc.

In pity soil the main component is organic substances of soil. The soil, nwhich content the big-size of grain (sand, subs and), have a big pores. At the nsame time, the size of that pores is not very big: it is near 25-40 % from ngeneral volume of soil. The soil, which content the big size pores, have a good npenetration for water and air, that is why it’s dry and content much air in it.The soil, which have the small size of grain ( it’s clay nand peat) content the big number of small pores; the clay have 45-50% of pores nand peat have – to 84% once. In consequence, the soil of small nsize of pores, nwhich have the grain of nsmall size – have bigger dampness nand bad penetration nfor water and air.

According nto cleanness the soil nis divided on

Methods of sanitary analysis of soil:

        sanitary entomological

        sanitary-helmontologic nanalysis

        sanitary-biological

        sanitary-chemical

        sanitary-physical

        sanitary-radiological

 

 There are the indices of soil ndisperse capacity.

  The disperse properties of soil determine its air ncontent: filtration capacity, water content, capillarity, hygroscopic nproperties, evaporation capacity.

  The epidemiological importance of soil depends on its ncapacity of infections, invasions and infestations spreading.

  Ecologic and epidemiological analysis of soil should ninclude the evaluation of their biogeocenoses, the following ways of toxic, radioactive and biological nagents transmission are possible:

  Sanitary-entomological studies determine a number of nwinged flies, maggots, pre-chrysalis and chrysalis.

  Sanitary-helminthological analysis defines quantity of nhelminthes eggs and larvae.

Cleaning of the soil

Self-regeneration of soil results nin destruction of organic compounds to the level of mineral salts: nitrites, sulfates, carbonates which can be consumed by nplants. Pathogenic microflora perishes suppressed by nthe antagonistic soil microbes associations and the soil chemical aggression. nHelminthes eggs are being destroyed by UV sun radiation, parching etc. Fitoncides produced by some plants are able to kill npathogenic microbes.

  Nitrification is the basic nprocess of soil regeneration. It’s the conversion process of restored organic nnitrogen compounds into oxydated inorganic ones. nThere are heterotrophic and autotrophic nitrification ways. Heterotrophic nnitrification is performed by living organisms (fungi included), which affect nboth organic and inorganic niter compounds Nitrification is the basic natural way of nitrates nconversion. The optimum temperature range for nitrificating nbacteria is 25-37°C, the nprocess fails under 3°C nand over 50°C. nMost nitrificators are aerobic, their growth and ndevelopment claims good soil aeration. The most active nitrification processes nrun in porous soils with particles sized 2-10 mm (sandy soils, sandy nloam, black earth). Soil cultivation and ploughing helps aeration. Soil humidity under 25-30% nsuppressed nitrification.

NITROGEN nCYCLE

  The most interesting of all vital phenomenon taking place in soil is disposal and utilizatioof organic matter. This is illustrated by nitrogen cycle.

 STEPS:       

Organic nproteins burried in soil are decomposed by nputrefactive bacteria. Result is formation of amino compounds & thethese compounds are broken down into NH₃ & CO₂.

 CO₂ escapes from these ncompounds in atmosphere.

 Ammonia in soil is converted into nammonium chloride or ammonium carbonate.     In soil, ammonia is oxidized by naction of nitrifying bacteria first into nitrates and then iitrites.

 Nitrites are taken up by plants, nwhich are in turn taken up by animals. If nitrites are found in soil water, it nindicates pollution and signifies active bacterial action and presence of norganic matter. Nitrates alone are index of past pollution only.

            Significance of Nitrogen Cycle

.Purification of atmosphere

Organic decomposition

3.     nFertilization power of soil nincreases

Nitrate (NO₃) containing water is npreferred. It is further purified.

 

Сleaning  of populated places

Disposal of Solid Wastes

Solid nwastes include domestic refuse and other discarded solid materials, such as nthose from commercial, industrial, and agricultural operations; they contaiincreasing amounts of paper, cardboard, plastics, glass, and other packaging nmaterials, but decreasing amounts of ash. The amounts produced are increasing nthroughout the world; urban wastes alone amount to about 600 kg per capita annually, and for industrialized countries pro­bably at nleast 700 kg nper capita, with an annual increase nof 1-2 %. As the density of domestic waste is decreasing, annual per capita volumes of up to 5 cubic metres nare common. These figures do not include the additional solid wastes produced nby agricultural and industrial operations, and as a by­product of sewage ntreatment.

The ninsanitary collection and disposal of solid wastes creates serious health nhazards, e.g., by encouraging the breeding of flies, mosquitos, nrodents, and other vectors of disease. It may also contribute to water npollution, air pollution, and soil pollution. It has adverse effects on land nvalues, constitutes a public nuisance, and thus contributes to the deteriora­tioof the environment.

The nappropriate intervention and control measures are the rapid removal of refuse nfrom premises by an efficient collection system and the proper processing of nrefuse before final disposal or re-use.

A nrefuse disposal system includes essentially: (1) the transportation system, nusing automotive vehicles, railway transport, pneumatic transport in pipelines nunder vacuum, and liquid transport in trunk sewers. Transfer stations for nchanging from one method of transport to another (e.g., truck hauling to nrailway hauling) are also necessary; (2) facilities for the pro­cessing of nsolid wastes, possibly using one or more of the following tech­niques: nsegregation of refuse components, incineration, composting, pulverization, ncompaction, and grinding; and (3) facilities for the sanitary discharge of nresidues into the environment, e.g., sanitary landfill, controlled discharge ninto bodies of water, and discharge into the air of combustion gases and nparticulate matter.

There nare numerous alternatives for the handling and disposal of solid wastes. Iselecting the best, consideration must first be given to the protection of the nhealth of the community and the prevention of public nuisances. The salvaging nof constituents of refuse, such as paper, glass, steel, etc., for re-use by nindustry must also be considered.

Methods of collection and disposal

The nrapid increase in the production of wastes is causing storage, collection, and ntransportation difficulties, as well as problems of treatment and final ndisposal.

Storage nis largely a local problem; it becomes acute in housing develop­ments and napartment blocks where adequate provision for storage has not been made. nCollection and transportation have recently been intensively studied in various nparts of the world, using operations research techniques, with a view to nimproving efficiency and lowering costs. Unconventional systems, such as nhydraulic or pneumatic transport in pipes, are being developed, especially for nnew towns and residential areas. These developments, which are very promising, nwill eventually reduce collection costs and minimize human contact with solid nwastes.

Collectioand transportation costs vary widely, depending on popula­tion density, route nplanning, the location of disposal sites, labour ncosts, etc. Careful planning of routes and of pick-up procedures should make nsignificant savings possible.

Substantial nsavings in handling costs can be achieved by conservation (reducing the volume nof waste), land disposal and on-site treatment, both anaerobically nor through the use of oxidation ponds or aeration ditches.

The nmost difficult problem, however, remains that of disposal. Because nof the potential nuisance involved, the choice of disposal sites is often a nsource of serious” controversy. Ideally, the site should be nselected or the basis of regional studies. The disposal methods of choice are nincineration, sanitary landfill, and composting. Unfortunately, indiscriminate ndumping is still practised, both on land and on sea. nIncinerator design is improving as combustion efficiency improves and greater ncontrol is obtained over gaseous emissions; even after incineration, however, a nsizeable volume of ash remains.

Composting, nalthough it has widespread popular appeal, has become increasingly uneconomical nas a means of disposal, both because of the changing nature of refuse and the ndifficulty in disposing of the compost itself.

Sanitary nlandfill is everywhere the most popular method of disposal. While it requires nthe use of relatively large areas, it can be used effectively for land nreclamation purposes; when properly managed it can be inoffensive, and avoid nboth air pollution and, to a large extent, leaching and resulting water npollution. A modification of the process is being developed in certain areas; nrefuse is hauled relatively long distances by rail, and disposal is combined nwith strip-mining operations.

Other nprocesses, still at the experimental stage, include pulverization into a dense, nhomogeneous, and relatively inoffensive material. This process reduces ntransport costs and land area requirements for sanitary landfill. nInvestigations are also being carried out on the high-pressure compaction of nrefuse into blocks of high density. These blocks could be used as a filling nmaterial and for the reclamation of derelict land.

The nimportance of recycling in refuse disposal has been emphasized by the nconservation-minded. It is almost always a marginal operation from an economic npoint of view, although aluminium, glass, iron, npaper, and other materials can be reclaimed.

Sanitary purification of settlements

 

It is a set of measures that provide nfor the fulfillment of nhygienic requirements during arrangement and exploitation of equipment and facilities that are meant for collecting, temporary keeping, ntransportation, ndestruction and utilization of solid and liquid ndomestic and industrial waste.

Waste – these nare remains of substances and articles that have been created as the result of ndomestic, economic and industrial human activity, and cannot be used at the scene of their creation so that their accumulation and nkeeping make the sanitary condition of the environment worse. They are divided into liquid: 1) sewage nfrom cesspool toilets; 2) slops n(from cooking and dish and floor washing etc.) and n3) waste waters: domestic, industrial, runoffs, municipal waste water and solid: 1) garbage n(domestic refuse); 2) rubbish (kitchewaste products); 3) waste from patient care and nprophylaxis institutions (including nspecific ones –– used dressing, used disposable autotransfusers and syringes, remains of medicines, remains nof organs and tissues after surgical operations, dead bodies of laboratory nanimals etc.); 4) institutional waste n(schools, preschool institutions, high schools and nacademies, offices, etc; 5) waste of public catering establishments; n6) waste of animal origin n(dead bodies of animals, npus, forfeit foodstuff); n7) waste of commercial facilities; n8) industrial waste; n9) slags from boiler nhouses; 10) construction waste, urban soil; n11) street sweepings.

 

There are three different nsystems of waste ndisposal: “flushing” removal, “pick-up” removal nand combined removal.

Flushing system is used in the settlements, which are provided with nsewerage (pipe) system through which liquid and partially fine solid waste float to nwaste disposal plants; the rest of nsolid waste is removed by special motor transport.

Pick-up system is used in the nsettlements without sewerage systems. At that both liquid and solid domestic waste (SDW) is removed to areas of disposal and utilization by special motor transport. Such nmethod of disposal of solid waste is called purification, and of liquid wastes – sanitation.

Combined system is used in the settlements that are partially provided with nsewerage system. According to combined system liquid waste from the part nof settlement, nprovided with sewerage system, is removed through this system, and from the part of the settlement where there is no sewerage system – nwith the help of cesspoolage transport. All solid nwaste is removed by nsanitary purification transport.

Sanitary purification of settlement must be systematic (to be performed according to agreed plan and schedule), nregular (waste removal nin warm season – daily, icold season – once per 1-3 days), nutility (to be performed by utilities and ncommunity services, or trusts) and to be nindependent from wishes of some officials or institutions. It consists nof three stages: nI –– collection and temporary keeping nof solid domestic waste; II –– removal; nIII –– disposal and treatment.

Collection, removal (transportation) of nsolid domestic wastes.

In case of neighbourhood-based system SDW is collected into special dustbins that are located at specially arranged plots on the territory near nthe houses and later on, according nto the schedule, it is removed by special motor transport to the place of disposal. In case of door-to-door-based nsystem waste is collected in apartments. At the certain time inhabitants take it out to a dust–cart. There are two different methods used icase of neighbourhood-based system – nmethod of “fixed” ncontainer (waste from dustbins is emptied into dust–carts and dustbins are placed back) and method of n“disposeable” container (dustbins together with solid waste are removed by dust-carts to waste disposal places, while nempty and clean dustbins are left ninstead of the used ones).

For garbage and other solid waste removal special motor cars – ndust–carts ‑ are used. For method of “fixed” container they use dust–carts 93/М, 53/М, nКО-404, КО-413 etc., nfor method of “ disposeable n” container – ndust–carts М-30. They are mounted on the chassis of nthe trucks GAZ-93а, GAZ -53, MAZ n-500А.

Solid domestic waste disposal. All methods of SDW disposal have to nmeet the following basic hygienic requirements:

– they must provide reliable disposal, transformation of waste into nharmless from epidemic and sanitary point of view substrate. From epidemic point of view solid domestic waste is very dangerous: when titer is n10^-6-10^-7, titer of anaerobes is – n10^-5-10^-6, microbial number achieves tens and nhundreds of billions, contains pathogenic and nconditionally pathogenic bacteria, viruses, eggs of helminthes. Especially dangerous is waste from patient care and prophylaxis institutions, which nis approximately 10-100 times more contaminated by nmicroorganisms than domestic waste;

– quickness – ideal method is the one nthat makes possible effective waste disposal nduring the same period of time iwhich the waste is formed;

– they must prevent laying eggs and nlarvae and chrysalides development of flies (Musca domestica) both nin waste during its disposal and in substrate, which was obtained in the result nof the disposal;

– they must prevent access of rodents during waste disposal and to convert waste into nunfavourable for their life and development substrate;

– they must prevent air pollution by nvolatile products of demolition of organic substances (SDW contain up to n80 % of organic substances, n20-30 % of which easily rot in summer and at the same time evolve nstinking gases: hydrogen sulphide, indole, skatole nand mercaptans);

– in the process of waste disposal neither surface nor ground waters may be polluted;

– they must provide the nbest and safe for people’s health use of SDW nproperties, because they contain up to n6% of utilizable waste; by its burn one can receive heat energy, by nbiothermal treatment –– organic nfertilizers, and food waste may be used for cattle nfeeding.

According to the nfinal result methods of SDW disposal are divided into: utilizing (waste processing into organic fertilizers, biological fuel, separation of secondary raw materials, e. g. scrap metal, for industry, use as a power–plant fuel) and nliquidation (land disposal, sea disposal, incineration without nhelp of heat). According to technological principle methods of disposal are divided into: n1) biothermal n(plough-lands, improved dumps, waste store grounds, nwaste composting fields, bio–chambers, plants for biothermal treatment; in rural area in farms n–– compost heaps, hotbeds); n2) thermal (combustion plants without or nwith utilization of heat energy, which is ncreated in the result of this process; pyrolysis nleading to formation of fuel gas and similar to mineral oil – lubricating oil); 3) chemical (hydrolysis); n4) mechanical (waste separation with further nutilization,  pressing ninto construction blocks); 5) combined.

Most widely used are biothermal methods. They are based on the complicated processes of soil natural organic purification from pollutants that may be represented idiagram:

 

 

Biothermal disposal makes it possible to solve two tasks: n1) to decompose complex organic matters of waste and its metabolism products n(urea, uric acid etc.) into simpler compounds in order to synthesize by special microorganisms in presence of ambient air a new, stable, safe from sanitary point of view substance, called humus; n2) to destroy vegetative forms of pathogen and conditionally pathogenic nbacteria, viruses, protozoa, eggs of helminthes, neggs and larvae of flies, seeds of weeds.

Efficiency of biothermal method of waste ndisposal depends on:

– aeration of nwaste (it is necessary to fan 25 air volumes nfor 1 volume of SDW);

– waste moisture (if moisture n< 30 %, SDW must be moistened artificially; if n> 70 %, it is nnecessary to install  devices for its nlessening);

– content of organic substances in waste that are capable to rot easily (mustn’t nbe  < 30 %, ithe ration of carbon to nitrogen 30:1), and ninorganic compounds (less than 25 %); n

– waste particles’ size (optimal nsize is 25-35mm);

– waste active nreaction (рН) (optimal рН is n6.5-7.6);

– degree of output contamination by mesophilic and thermophilic microorganisms (artificial ninoculation is carried out for stimulation of purification);

– thermal conditions (more quickly temperature will rise in the thickness of waste, better and more reliable biochemical destruction of organic substances and pathogenic microflora will be). n

Sanitary inspection of systems of waste collection, transportation and disposal requires objective assessment of their efficiency, nwhich is impossible without territory sanitary survey, soil sampling and its nlaboratory analysis.

METHOD OF DETERMINATION OF nCONCENTRATION OF СО₂ IN THE AIR AS INDEXES OF ANTROPOGENIC CONTAMINATION OF AIR AND nVENTILATION OF APARTMENTS. CONCEPT ABOUT AN AIR CUBE, NECESSARY AND ACTUAL nVOLUME AND DIFFERENT nTYPES OF nVENTILATION, THEIR SCIENTIFIC GROUNDING.

Chemical composition of atmospheric air.

http://www.melbourne.vic.gov.au/info.cfm?top=171&pa=1943&pg=1934

Role of air in human health:

Air plays a vital role in our lives. It is our nimmediate environment and performs following functions.

§        nSupply oxygen for living

§        nSupply CO₂ to plants.

§        nKeeps body cool.

§        nHelps in smelling.

§        nHelps in listening.

Composition:

Air is a mechanical mixture of gases. The normal compositioof external air i.e. fresh air and of expired air is given below.

Minute amounts of other gases is present e.g. argon, nneon, krypton, xenon and Helium.

In addition to gases, air also contains water vapour, traces of ammonia and suspended matter such as ndust, bacteria, spores and vegetable debris.

 Under nordinary conditions the composition of outdoor air is remarkably constant. This nis brought about by certain self-cleansing mechanisms which operate iature nsuch as movement of air, sunlight, rain, atmospheric temperature and plant nlife.

http://www.treepics.co.uk/education/co2cycle.php

Air content change in act nof breathing.

The contents of the carbon dioxide in the nexternal atmosphere is from 0,03 to 0,04 %. The nincreased contents of carbon dioxide have the negative influence on the humaorganism:

a)     n3 % – the acceleration and deepening of breathing;

b)    n4 % – besides this the feeling of head pressure, headache, the noise in the nears, psychical excitement, heartbeeting, slowing ndown of the pulse, sometimes vomiting and syncope appear;

c)     n6-8 % – the above mentioned phenomena intensify;

d)    n10 % – stop of breathing;

e)     nmore than 10 % – paralysis of the brain centers and nthe death appear in some minutes.

  The individual sensitivity to the carbodioxide varies in different people. The patients with heart and lung diseases nsuffer more. 

 In the bad naired and overpopulated rooms the air has the specific smell because of the npollution from the products of the skin perspiration. Simultaneously in such rooms  the humidity nand the air temperature increase. Because of that in people appear   headache , the nappetite loss, the decreasing of the capacity for work and other violations.

There are the norms of  the contents of carbon dioxide iliving room, classroom (not more than 0,5-1%) in same time (the bomb and gas nshelters )- not more than 2 %.

Indoor Air nPollution

http://www.sustainablenc.org/thewaytogo/main/iaq.htm

We haves pent a considerable amount of effort and money to control the nmajor outdoor air pollutants, but we have only recently become aware of the ndangers of indoor air pollutants.

The EPA has found that concentrations of toxic air pollutants are nconsistently higher that outdoors – up to twenty times higher for some toxins.  Furthermore, people generally spend more time ninside than out and therefore are exposed to higher doses of these pollutants.

Pollution is perhaps most harmful at an often unrecognised site—inside nthe homes and buildings where we spend most of our time. Indoor pollutants ninclude tobacco smoke; radon, an invisible radioactive gas that enters homes nfrom the ground in some regions; and chemicals released from synthetic carpets nand furniture, pesticides, and household cleaners.

Pollutants may accumulate to reach much nhigher levels than they do noutside, where natural air currents ndisperse them. Indoor air levels nof many pollutants nmay be 2 to 5 times, and noccasionally more than 100 times, higher than outdoor nlevels. These levels of indoor nair pollutants are especially harmful because people spend as nmuch as 90 percent of their ntime living, working, and playing nindoors. Inefficient or improperly vented nheaters are particularly dangerous.

Smoking is without doubt the most important air npollutant in the United States in terms of human health. The SurgeoGeneral estimates that 400000people die each year in the United States from nemphysema, heart attacks, strokes, lung cancer, or other diseases caused by nsmoking. Banning smoking probably would save more lives than any other npollution-control measure.

Other major indoor air pollution health hazards ninclude asbestos, formaldehyde, vinyl chloride, radon, and combustion gases. nAsbestos was widely used in floor and ceiling tiles, plaster, cement, ninsulation, and soundproofing. It is a serious concern in indoor air because if nits carcinogenicity. Formaldehyde is used in more than 3 thousand products, nincluding such building materials as particle board, waferboard, nand urea-formaldehyde foam insulation. Vinyl chloride is used in plastic nplumbing pipe, floor and wall coverings, and countertops. New carpets and ndrapes typically contain two doses chemicals designed to kill bacteria and nmolds, resist stains, bind fibers, and retain colors.

In many cases, indoor air in home has concentrations of chemicals that nwould be illegal outside or in the workplace. The EPA has found that nconcentrations of such compounds as chlorophorm, nbenzene, carbon tetrachloride, formaldehyde, and styrene can be seventy times nhigher in indoor air than in outdoor air. Many people are highly sensitive to nthese chemicals, and it is not uncommon to trace illness to a “sick house nsyndrome” caused by polluted indoor air. Next to smoking, the most serious nindoor air pollutant in the United States is probably radon gas that leaks into nhouses from surrounding soil and rock.

In the less-developed countries of Africa, Asia and Latin America where nsuch organic fuels firewood, charcoal, dried dung, and agricultural wastes make nup the majority of household energy, smoky, poorly ventilated heating and ncooking fires represent the greatest source of indoor air pollution. The World nHealth Organization estimates that 2.5 billion people – half the world’s npopulation – are adversely affected by pollution from this source. Womeespecially spend long hours each day cooking over open fires or unventilated nstoves in enclosed spaces. The levels of carbon monoxide, particulates, aldehydes, and other toxic chemicals can be one hundred ntimes higher than would be legal for outdoor ambient concentrations in the United States. nDesigning and building cheap, efficient, nonpolluting energy sources for the ndeveloping countries would not only save shrinking forests but would make a nmajor impact on health as well.

Methods and devices of the air sampling for chemical nanalysis

There are two groups of methods – nlaboratory and express. These methods were elaborated and are widely used ithe sanitary inspection units for determination of the air pollution in the natmosphere, indoor and in factory working areas.

The aspiration method of the air nsampling is one of the laboratory methods. Using this method of sampling the nrequired air volume is passed though selected absorbing solutions in absorbing ndevices of different constructions (fig. 2) by an aqueous aspirator (fig. 1-a), na vacuum cleaner or the electrical aspirator (fig. 1-b). The investigated air nis delivered into the absorbing solution though the long tube of this device, nthen it is passed by short tube of the aspirator. Crystal absorbing reagents located in tubes – nallonges of special forms are widely used for this npurpose.

The air volume passed though the nabsorbing solution or the allonge is determined using na gas meter, an aqueous rheometer (fig. 10.3) or a nball rotameter measuring the air aspiration speed il/min. The gas meter or rheometer is concatenated nbetween the absorbing device and the aspirator. The required air volume is ndetermined for the particular chemical research (analyses) in accordance to the nappendix 2.

The air sampling for laboratory nanalyses may be selected in tubes of definite capacities by blowing the ninvestigated indoor air through them, or by pouring the water out from the tube ninside the investigated room. Gas pipettes (fig. 10.4), flasks and other ndevices are used.

The universal gas-analyzer UG-2 (УГ-2) (fig. n10.5, appendix 3), the gas-analyzer GMK-3 (ГМК-3) (fig. 10.6) and other devices may nbe used for the express methods.

 

Fig. 1 а – Aqueous naspirator (1), connected by rubber tube (2) with absorbing devices; b – nelectrical aspirator „Liot”

Fig. 2 nAbsorbing devices for the air sampling with liquid solutions

Fig. 3 Aqueous rheometer

Fig n. 4 Air sampling into gas pipettes:

а – nby air inflow (leak–in) nor pouring out; b – by nsiphon method.

Fig. 5 nUniversal gas-analyzer UG-2 (УГ-2) with the coloristical nscale

Determination of chemical pollutants in the air using ngas-analyzer UG-2 (УГ-2)

The ngas-analyzer is built using the linear-colorimetric principle: concentration of na chemical pollutant in the air is determined by the coloring of the indicating nreagent in a glass pipe after blowing the certain volume of the investigated nair though this. The indicating tube with the reagent is put on to the ncolorimetric scale. The different scale is provided with the device for each nair pollutant. Concentration of the searched substance is pointed on this ruler nin mg/m³.

14 chemical npollutants, usually met at manufacture may be determined using this device: nammonia, acetone, acetylene, benzene, benzole, xylol, carbon oxide, nitric oxides, sulfurous anhydride, nhydrogen sulfide, toluol, oil hydrocarbons, chlorine, nethylic ether.

The nindicating tubes with crystal reagents are prepared for the analyses and are nadded to the device.

Order of ntesting. Using rod with the required air volume for certaianalysis the air is blown from the air inlet siphon (rubber camera stretched by nthe spring) at the place of investigation (on the department, on the working nplace, at the pollution outburst spots). The certain indicating tube is nconnected to the rubber tube of the device and the required air volume is blowthough the rubber tube after releasing the rod from holding clamp. The nindicating tube is put onto the colorimetric ruler. The investigated pollutant nconcentration is determined by the changing of the length of the reagent nportion, that changes its color (becomes darkened).

Note. The indicating tubes and air pollutiosimulation by certain substance are prepared by the laboratory of the ndepartment because of the limited working time.

Hygienic ncharacteristics of the indoor sanitary condition and ventilation

1.        nThe chemical composition of the natmospheric air is: nitrogen – 78.1%; oxygen – 21.0%; carbon dioxide – n0.03-0.04%; inert gases – 0.7-1.0%; moisture usually from 40-60% till the full nsaturation; dust, microorganisms, natural and anthropogenic pollutions ndepending on the industrial development of the region, surface type (desert, nforest-covered region etc.)

2.        nThe main air pollution sources of the ninhabited regions and industrial areas are the nproduction plants, motorized transport; industrial dust and gas; meteorological nfactors (winds) and surface type of the regions (dust storms of arid nsettlements without green plantations).

3.        nThe main air pollution sources of the nresidential, communal, domestic and public premises are the products of the nhuman metabolism, generated by skin and respiration (sweat, skin fat, necrotic nepidermis degradation products and others). These products are thrown out into nthe indoor air proportionally to the number of people present and duration of ntheir stay indoor and carbon dioxide volume. The carbon dioxide is accumulated nin the air in proportion to the listed pollutants and may be used as aindicator of the pollution with these products.

4.        nThe organic metabolic products are nextracted though the skin and by respiration generally. That is why the air oxidability was suggested as the other pollution indicator nfor the assessment of the indoor air pollution induced by human. The oxidability index is measured as the atomic oxygen volume nrequired for oxidization of organic products in 1 m³ of nthe air using the solution of potassium dichromate К₂Сr₂О₇ nfor titration.

The air is npure if this index doesn’t exceed 4-6 mg/m³. The oxidability nair index may be 20 and above mg/m³ in the rooms with the adverse nsanitary state.

5. Indoor ncarbon dioxide concentration is increased proportionally to the number of npeople and duration of their stay inside. Although it normally does not reach nthe hazardous levels, nevertheless it does indicate the level of the air npollution with the other metabolism products. The carbon dioxide concentratiomay reach the hazardous for human organism or even life level only in the nenclosed non-ventilated areas (dug-outs, submarines, underground openings, industrial nareas, sewer systems etc.) due to fermentation, combustion, putrefaction.

The increase of the СО₂ nconcentration by 2-2.5% does not cause noticeable deviations in the humahealth and work ability, according to the research by M.P. Brestkin and other authors. Concentrations up to 4% may ncause the increase in the respiration intensity, the cardio-vascular functions nand reduction of the work capacity. Concentrations up to 5% are accompanied nwith dyspnea, increase of the cardiac function, ndecrease of workability. 6% СО₂ concentration causes the mental nactivity decrease, the headaches, dizziness; 7% causes the inability to control noneself, fainting and even death. 10% concentration results in rapid, and i15-20% cases – sudden death because of the respiratory paralysis.

Some methods were elaborated for CO₂ nconcentration determination in the air: method with barium hydrate by Subbotin-Nagorskiy, methods by Reberg-Vinokurov, nKalmikov, interferometrical nmethod. The portable express method by Lunge-Zeckendorf nmodified by D.V. Prokhorov is the most widely used in the sanitary npractice (see appendix 2).

Carbodioxide determination in the air using the express method by Lunge-Cekkendorf, modified by D.V. Prokhorov

The method is based on blowing the ninvestigated air through the sodium carbonate (or ammonia) volumetric solutioin presence of the phenol-phthalein. The Na₂CO₃+H₂O+CO₂=2NaHCO₃ nreaction takes place in this case. Pink in the alkaline medium, the phenol-phthalein is discoloured after nthe contact with CO₂ (acid medium).

The raw solution is prepared by ndilution of 5.3 g nchemically pure Na₂CO₃ into 100 ml of distilled nwater and 0.1% solution of phenol-phthalein is added nto the raw solution. Before analysis the work solution is prepared by dilatioof 2 ml raw solution to 10 ml by distilled water.

The solution is npoured into Drecsel’s bottle by nLunge-Zeckendorf method (fig. 11.1-а) or into nJanet’s syringe in Prokhorov’s modification (fig. 11.1-b). In the first case nthe rubber syringe with valve or small aperture (hole) is connected with the nlong tube of Drecsel’s bottle with thin beak. The ninvestigated air is blown though the solution by slow compression and fast nrelease. The bottle is shaken up till the total absorption of CO₂ nfrom the air sample after each blowing. In the second case (Prokhorov’s nmodification) the total air volume is collected into nthe Janet’s syringe, filled with 10 ml of the work soda solution with phenol-phthalein and held with the cannula nup, the syringe is also shaken up. The air volumes for discoloring of nthe solution are calculated. The air analysis is ncarried out indoor and outside (atmospheric air).

The result is calculated by the ninverse proportion under comparison of the used syringe volumes quantities and nCO₂ concentration in the atmospheric air (0.04%) and unknown СО₂ nconcentration in the certain investigated indoor premise. For example, 10 nsyringes were used indoors and 50 – outdoors. CO₂ concentration indoors =  (0.04×50) : 10 = 0.2%

CO₂ maximum nallowable concentration (MAC) of the indoors (premises of various purpose) is ndetermined at the level 0.07-0.1%, in industrial premises where CO₂ nis accumulated during manufacture processes – 1-1.5%.

Fig. nDevice for determination of СО₂ concentration by Lunge-Cekkendorf

(а – rubber syringe for the air blowing with valve; б – Drecksel’s bottle with soda solution and phenol-phthalein)

 

Fig. Janet’s syringe for determination of СО₂ concentration by nD.V. Prokhorov

Methods of determination and nhygienic assessment of the air circulation and indoor ventilation

The indoor air is considered pure if nCO₂ concentration does not exceed the maximum allowable nconcentrations – 0.07% (0.7‰) by Pettencofer or 0.1% n(1.0‰) by Flugge.

In accordance to this statement the nrequired ventilation volume is calculated. The required ventilation volume is the volume of the fresh air, which nis to be drawn inside so, that CO₂ concentration does not exceed the nallowable value. This volume is calculated using the following formula:

V=

where: nV – ventilation volume, m³/hour;

К – volume of СО₂, nexpired by one person per hour (in calm conditions 21.6 l/hour; while sleep – n16 l/hour; performing the job of different heaviness – 30-40 l/hour);

n – the number of people inside;

Р – СО₂ maximum nallowable concentration in pro mil (0.7 or 1.0‰);

Р₁ – nСО₂ nconcentration in the atmospheric air in pro mil (0.4‰).

The calculation of the СО₂ nvolume expired by one person per hour is based on the CO₂ nconcentration in the expired air (4%), inspiration and expiration rate (under ncalm conditions – 18 inspirations per minute × 60 = 1080 per hour) and nexpired air volume – 0.5 l nper one expiration, and this totals to:

1080 × 0,5 n= 540 l/hour.

Using the following proportion: 4 l – 100 l, х – n540 l, nthe expired CO₂ volume may be calculated:

х =  = 21.6 l/hour

The respiration rate, expired СО₂ nvolume and required ventilation volume are increased during the physical nactivity in proportion to their heaviness and intensity.

Required nventilation rate (air nexchange rate) is the number, demonstrating how many times the indoor air nhas to be completely renewed by the ventilation so, that nСО₂ nconcentration does not exceed the maximum allowable concentration (MAC).

Required nventilation rate (air exchange rate) is found by ndividing the calculated required ventilation volume by the indoor cubature.

Actual nventilation volume is found by determination of the nventilation source area and the speed of the air movement through it (e.g. ntransom, wicket). The air volume equal to the indoor cubage (cubature) is drawinside through the wall perforations, windows slits and doors, and it must be nadded to the volume of the air, drawn through the ventilation.

Actual nventilation rate (air exchange rate) is ncalculated by dividing the actual ventilation volume by the indoor cubage n(cubature).

The indoor air change efficiency may nbe determined comparing the required and actual volumes and ventilation rates.

The air ventilation rate standards for different npremises

 

 

Effects of nAir Pollution

So nfar we have looked at the major types and sources of air pol­lutants. Now we nwill turn our attention to the effects of those pollutants on human health, physical nmaterials, ecosystems and global climate.

The nprimary human health effects of most air pollutants seems nto be injury of delicate tissues, usually by damaging cellular membranes. This noften sets in motion an inflammatory re­sponse, na complex series of interactions between damaged cells, surrounding ntissues, and the immune system. One of the first symptoms of inflammation is nleakage of fluid (plasma) from blood vessels. Exposure of respiratory tissues nto severe irritants can result in so much edema (fluid accumulation) in the nlungs that one effectively drowns.

Bronchitis is na persistent inflammation of bronchi and bronchioles (large and small airways nin the lung) that causes a painful cough, copious production of sputum (mucus nand dead cells), and involuntary muscle spasms that constrict airways.

Acute nbronchitis can obstruct airways so severely that death results. Smoking is nundoubtedly the largest cause of chronic bronchitis in most countries. nPersistent smog and acid aerosols also can cause this disease.

Severe nbronchitis can lead to emphysema, airreversible obstructive lung disease in which airways become permanently nconstricted and alveoli are damaged or even destroyed. Stag­nant air trapped iblocked airways swells the tiny air sacs in the lung (alveoli), blocking blood ncirculation. As cells die from lack of oxygen and nutrients, the walls of the nalveoli break down, creating large empty spaces incapable of gas ex­change n(fig. 18.10). Thickened walls of the bronchioles lose elasticity and breathing nbecomes more difficult. Victims of emphysema make a characteristic whistling nsound when they breathe. Often they need supplementary oxygen to make up for nreduced respiratory capacity.

Cardiovascular nstress from lack of oxygen in the blood is a common complication of all nobstructive lung diseases. About twice as many people die of heart failure nassociated with smoking as die of lung cancer.

Irritants nin the air are so widespread that about half of all lungs examined at autopsy nin the United States nhave some de­gree of alveolar deterioration. The Office of Technology As­sessment n(OTA) estimates that 250,000 people suffer from pollution-related bronchitis nand emphysema in the United States, and some 50,000 excess deaths each nyear are attribut­able to complications of these diseases, which are probably nsecond only to heart attack as a cause of death.

Asthma is a distressing ndisease characterized by unpre­dictable and disabling shortness of breath ncaused by sudden episodes of muscle spasms in the bronchial walls. These nattacks are often triggered by inhaling allergens, such as dust, pollen, an­imal ndander, or corrosive gases. In some cases, there is no apparent external nfactor, and internal release of triggering agents is suspected. It isn’t knowwhether asthma is genetic, environmental, or a combination of the two.

Fibrosis is the general nname for accumulation of scar tissue in the lung. Among the materials that ncause fibrosis are silica or coal dust, asbestos, glass fibers, beryllium and naluminum whiskers, metal fumes, cotton lint, and irritating chemicals, such as nthe herbicide paraquat. We give each of these ndiseases an individual name (silicosis, black lung, asbestosis, beryllium lung ndisease, brown lung, or paraquat lung), but they nreally are very similar in development and effect. Cells respond to irritants nand foreign material in the lungs by sealing off damaged areas with scar tissue n(produced ei­ther by interstitial cells in the walls of airways or by the ep­ithelial nlinings). As the lung fills up with fibrofic tissue, nrespiration is blocked and one slowly suffocates. In some cases, cell growth nstimulated by the presence of foreign material in the lung results in tumor nformation. Lung cancers are often lethal.

Local and regional pollution take nplace in the lowest layer of the atmosphere, the troposphere, nwhich at its widest extends from Earth’s surface to about 16 km. The troposphere is the nregion in which most weather occurs. If the load of pollutants added to the ntroposphere were equally distributed, the pollutants would be spread over vast nareas and the air pollution might almost escape our notice. Pollution sources ntend to be concentrated, however, especially in cities. In the weather nphenomenon known as thermal inversion, a layer of cooler air is trapped near nthe ground by a layer of warmer air above. When this occurs, normal air mixing nalmost ceases and pollutants are trapped in the lower layer. Local topography, nor the shape of the land, can worsen this effect—an area ringed by mountains, nfor example, can become a pollution trap.

Smog is intense local pollution usually trapped nby a thermal inversion. Before the age of the automobile, most smog came from nburning coal. In 19th-century London, nsmog was so severe that street lights were turned on by noon because soot and nsmog darkened the midday sky. Burning gasoline in motor vehicles is the maisource of smog in most regions today. Powered by sunlight, oxides of nitrogeand volatile organic compounds react in the atmosphere to produce photochemical nsmog. Smog contains ozone, a form of oxygen gas made up of molecules with three noxygen atoms rather than the normal two. Ozone in the lower atmosphere is a npoison—it damages vegetation, kills trees, irritates lung tissues, and attacks nrubber. Environmental officials measure ozone to determine the severity of nsmog. When the ozone level is high, other pollutants, including carbomonoxide, are usually present at high levels as well.

  Ithe presence of atmospheric moisture, sulfur dioxide nand oxides of nitrogen turn into droplets of pure acid floating in smog. These nairborne acids are bad for the lungs and attack anything made of limestone, nmarble, or metal. In cities around the world, smog acids are eroding precious artifacts, including the Parthenon temple in Athens, Greece, nand the Taj Mahal in Agra, India. nOxides of nitrogen and sulfur dioxide pollute places nfar from the points where they are released into the air. Carried by winds ithe troposphere, they can reach distant regions where they descend in acid nform, usually as rain or snow. Such acid precipitation can burn the leaves of nplants and make lakes too acidic to support fish and other living things. nBecause of acidification, sensitive species such as the popular brook trout cano longer survive in many lakes and streams in the eastern United States.

Smog spoils views and makes outdoor activity unpleasant. For the very nyoung, the very old, and people who suffer from asthma or heart disease, the neffects of smog are even worse: It may cause headaches or dizziness and cacause breathing difficulties. In extreme cases, smog can lead to mass illness nand death, mainly from carbon monoxide poisoning. In 1948 in the steel-mill towof Donora, Pennsylvania, intense local smog killed 19 npeople. In 1952 in nLondon about n4,000 people died in one of the notorious smog events known as London Fogs; i1962 another 700 Londoners died.

Air pollution can expand beyond a regional area nto cause global effects. The stratosphere is the layer of the atmosphere nbetween 16 km n(10 mi) nand 50 km n(30 mi) nabove sea level. It is rich in ozone, the same molecule that acts as a npollutant when found at lower levels of the atmosphere in urban smog. Up at the nstratospheric level, however, ozone forms a protective layer that serves a nvital function: It absorbs the wavelength of solar radiation known as nultraviolet-B (UV-B). UV-B damages deoxyribonucleic acid (DNA), the genetic nmolecule found in every living cell, increasing the risk of such problems as ncancer in humans. Because of its protective function, the ozone layer is nessential to life on Earth.

With stronger pollution controls and less reliance on coal for heat, ntoday’s chronic smog is rarely so obviously deadly. However, under adverse nweather conditions, accidental releases of toxic substances can be equally ndisastrous. The worst such accident occurred in 1984 in Bhopal, India, whemethyl isocyanate released from an American-owned nfactory during a thermal inversion caused more than 3,800 deaths.

 Several npollutants attack the ozone layer. Chief among them is the class of chemicals nknown as chlorofluorocarbons (CFCs), formerly used as refrigerants (notably iair conditioners), as agents in several manufacturing processes, and as npropellants in spray cans. CFC molecules are virtually indestructible until nthey reach the stratosphere. Here, intense ultraviolet radiation breaks the CFC nmolecules apart, releasing the chlorine atoms they contain. These chlorine natoms begin reacting with ozone, breaking it down into ordinary oxygemolecules that do not absorb UV-B. The chlorine acts as a catalyst—that is, it ntakes part in several chemical reactions—yet at the end emerges unchanged and nable to react again. A single chlorine atom can destroy up to 100,000 ozone nmolecules in the stratosphere. Other pollutants, including nitrous oxide from nfertilizers and the pesticide methyl bromide, also attack atmospheric ozone.

  Scientists are finding that under nthis assault the protective ozone layer in the stratosphere is thinning. In the nAntarctic region, it vanishes almost entirely for a few weeks every year. nAlthough CFC use has been greatly reduced in recent years and will soon be nprohibited worldwide, CFC molecules already released into the lower atmosphere nwill be making their way to the stratosphere for decades, and further ozone nloss is expected. As a result, experts anticipate an increase in skin cancers, nmore cataracts (clouding of the lens of the eye), and reduced yields of some nfood crops.

Table 1:  Sources, Health and Welfare Effects for nCriteria 
n
n

 

 

Systems nof Ventilation

http://www.minesafe.org/underground/ventilation.htmlventil

(a) Natural Ventilation. This nis greatly achieved by building houses having sufficient open space and by having na large number of windows opening direct into the open air. It largely depends non the following three natural for­ces:

(1)       Diffusion of Gases. Gases diffuse inversely as the square root of their densities, so the nair of room diffuses through the cracks and crevices of various doors and nwindows of a room, even though they are closed. But under ordinary ncircumstances, the diffusion if there be any, is-very small. So none cannot depend upon diffusion alone. Diffusion causes the gaseous nimpurities of the respired air to mix up with the fresh air of the room until nhomogeneity is established. Diffusion, however, does not affect the suspended nmatter present in the air which tends to fall back towards the earth in the nstill atmosphere, due to gravitational force.

(2)       Effects of Differences of Temperature. When air is heated, it expands and becomes lighter. This hot air rises nup and the cold fresh air rushes in to take its place.

If the air of a room is heated by nfire or gets heated from the products of respiration of men and animals or be made more or less moist, it tends to expand and rises up nor escapes through all available open­ings, cracks, or crevices. The outer ncolder air rushes in through outer openings until temperature of both outside nand inside air becomes same. Therefore, in all methods of ventilation based nupon the force, suitable and adequate inlets for fresh air and outlets for the nescape of impure air must be provided. This method is more relied upon in cold ncountries where coal fires are used and the external and internal dif­ference nof temperature of the room is relatively high. But in hot countries, where ndifference of temperature between the external and the internal air is small, nventilation is imperfect.

(3)       Perflation and nAspiration. Winds are very powerful ventilating nagents and they act in two ways: (i) by perflation and (ii) by their aspiration action.

(i) nPerflation means nthe setting up of masses of air in motion and forcing them through open doors, nwindows and porous bricks into the room as a result of movement of natural air currents. By means of this force nthe building can be rapidly and continuous­ly flushed with fresh air. Cross nventilation means free perflation between windows and nother openings, placed opposite to each other. But natural cross ven­tilatiois not feasible in the case of houses having back to back construction. Icountries having warm climates, as in India, where the inside and outside ntemperature of a room is more or less the same, ventilation is promoted by perflating action of the air through doors and windows and nas much care should be taken that as far as possible these should be facing neach other. Similarly pervious walls such as bamboo matting also allow free perflating without any harm whatsoever.

(ii) Aspiration means the suction action of the wind, which draws air out of a space, ncreating therein a partial vacuum and thus fresh air rushes in to take its nplace and a continuous current in perpendicular direction is thus set up. The naspirating action of wind is utilised to ventilate nrooms by means of provision of chimneys. When fire is kept burning in the ngrates, the aspirating action of chimneys is further in­creased.

http://www.minesafe.org/underground/ventilation.html

Natural air supply with mechanical air exhaust 

 

This is a popular form of ventilatioin residential buildings and offices.

The mechanical air exhaust system ncreates an underpressure in the building, through nwhich the system is less dependent on the weather than fully natural nventilation. The underpressure creates a pressure ndifference over the ventilation openings, so air is suck in. But never the less na high wind pressure or temperature difference can result in draught problems. nTo prevent draught the air supply openings have to be placed as high as npossible and the air inlet grid must have a possibility to be regulated.

A controllable exhaust ventilator ncontrols the ventilation capacity. In residential buildings suction takes place nfrom at least the kitchen, the bathroom and the toilet. Suction ducts are nneeded. Ion-residential buildings suction mostly takes place from the ncorridor.

n

Mechanical Supply and Exhaust

A mechanical ventilation system can be combined with all sorts of nheating and cooling systems. Often the heating, cooling and ventilation of a nbuilding are combined in the air-conditioning system.
n
nIn a mechanical ventilation system the supply air and the exhaust air are ntransported mechanically. Advantages of nmechanical ventilation are:

1.                      nGood control of the nventilation capacity; no dependence of the outdoor weather conditions and despite npossible noisy environment

2.                      nThe possibility of nextracting heat from the exhaust air and use it to preheat the fresh air supply n(heat recovery)

3.                      nThe possibility of npreheating and pre-cooling of the air supply

4.                      nThe possibility of nhumidify and dehumidify of the air supply

5.                      nThe possibility of ncleaning the air by an air filter or supplying the air from a relative cleasite of the building

By controlling the ventilators it is possible to control the ventilatiocapacity of the system. To prevent draught the air supply in the room has to be nplaced as high as possible. By preheating the incoming air draught problems are nalso decreased.
nThe location of the air exhaust grid is of less importance. Even high exhaust nvelocity caot produce draught. Yet the air exhaust velocity is restricted, nbecause high air velocity (globally above 2 m/s) in the ducts causes noise.
nFor proper functioning of the system the building has to be sufficiently nairtight.

 

 

The nkinds of the apartments ventilation

Artificial Ventilation. Natural nsources of ventilation are not nconsidered practical in Europe and in the case of large buildings, where a number of npeople are congregated for a nconsiderably long period and where nclimatic conditions do not permit free use of open doors and windows. Consequently, artificial ventilation is largely resorted to iplaces such as theatres, ncinemas, examination halls and schools. In this system mechanical means are nused to facilitate the renewal of air. The systems of artificial ventilation are as follows:

1.     nInflowing ( the fresh air is supplied  into the room by the ventilator, the polluted nair is removed by the natural way);

2.     nExtract ventilation ( the air from the room is succened off by the ventilator and the fresh air comes nnaturally);

3.     nThe inflowing-extract ventilation ( the ventilator succenes the atmospheric air and after the purification, nwarming and moistening it comes through the inflowing channels).

    The air nconditioning is the creation and automatically supporting of the optimal ntemperature, moisture and the speed of air motion, also the ionization, if nneeded in the room. There are central and local conditioners.  Conditioned air in the lecture-room, cinemas nand other on the  head nlevel must be :

       the air temperature is 20-22^ο C,

       the moisture is 40-60%,

       the speed of air motion is 0,15 m/s ( not more than 0,3).

http://irc.nrc-cnrc.gc.ca/pubs/ctus/15_e.html

VENTILATION is a system of intake and exhaust that creates a flow nof air.

AIR EXCHANGE n- the system of intake and exhaust that occurs with neffective air circulation.

Ventilation may be deficient nin:

·  confined spaces;

·  facilities failing to provide adequate nmaintenance of ventilation equipment;

·  facilities operated to maximize energy nconservation;

·  windowless areas; and

·  areas with high noccupant densities.

Any nventilation deficiency must be verified by measurement.

There are two basic types of nventilation systems:

        natural;

        artificial;

Combination of both is called mixed ventilation.

Artificial ventilation can be general or local, plenty, nexhaust or balanced. Combination of general and local ventilation is called combined ventilation.

They used plenty ventilation for prevention of indoor pollution nin the operational nroom, aseptic boxes etc.

Industrial ventilation generally involves the use nof supply and exhaust ventilation nto control emissions, exposures, and chemical hazards nin the workplace. nTraditionally, nonindustrial nventilation systems commonly known as heating, ventilating, nand air-conditioning (HVAC) nsystems were built to control ntemperature, humidity, and odors.

Inadequate or improper ventilation is nthe cause of about half of all indoor air quality (IAQ) problems inonindustrial workplaces. This section of the manual addresses ventilation icommercial buildings and industrial facilities.

INDOOR AIR CONTAMINANTS include but are nnot limited to particulates, pollen, microbial agents, and organic ntoxins. These can be transported nby the ventilation nsystem or originate in the nfollowing parts of the ventilation nsystem:

·  wet filters;

·  wet insulation;

·  wet undercoil pans; n

·  cooling towers; and

·  evaporative humidifiers.

People exposed to these agents may ndevelop signs and symptoms related to “humidifier fever,” n”humidifier lung,” or “air conditioner lung.” In some ncases, indoor air quality contaminants cause clinically identifiable conditions nsuch as occupational asthma, reversible airway disease, and hypersensitivity pneumonitis.

VOLATILE ORGANIC AND REACTIVE nCHEMICALS (for example, formaldehyde) often contribute to nindoor air contamination. The facility’s ventilation system may ntransport reactive chemicals from a source area to other parts of the building. nTobacco smoke contains a number of organic and reactive chemicals and is oftecarried this way. In some instances the contaminant source may be the outside nair. Outside air for ventilation or makeup air for exhaust systems may bring ncontaminants into the workplace (e.g., vehicle exhaust, fugitive emissions from na neighboring smelter).

General exhaust nventilation (dilution ventilation) is appropriate when:

·   nEmission sources contain materials of relatively nlow hazard. (The degree of nhazard is related to toxicity, ndose rate, and individual susceptibility);

·   nEmission sources are primarily nvapors or gases, or small, nrespirable-size aerosols (those nnot likely to settle);

·   nEmissions occur uniformly;

·   nEmissions are widely dispersed; n

·   nModerate climatic conditions prevail;

·   nHeat is to be nremoved from the space by nflushing it with outside air; n

·   nConcentrations of vapors are nto be reduced nin an enclosure; nand

·   nPortable or mobile emission nsources are to be controlled. n

Local exhaust ventilating is nappropriate when:

·   nEmission sources contain materials of relatively nhigh hazard;

·   nEmitted materials are primarily nlarger-diameter particulates (likely nto settle);

·   nEmissions vary over time; n

·   nEmission sources consist of point sources; n

·   nEmployees work in the nimmediate vicinity of the emission nsource;

·   nThe plant is located nin a severe climate; and

·   nMinimizing air turnover is nnecessary.

MAKE-UP AIR SYSTIS. Exhaust ventilation systems require the nreplacement of exhausted air. Replacement air is often called make-up air. nReplacement air can be supplied naturally by atmospheric pressure through opedoors, windows, wall louvers, and adjacent spaces (acceptable), as well as nthrough cracks in walls and windows, beneath doors, and through roof vents n(unacceptable). Make-up air can also be provided through dedicated replacement nair systems. Generally, exhaust systems are interlocked with a dedicated nmake-up air system.

Other reasons for designing and nproviding dedicated make-up air systems are that they: n

·   nAvoid high-velocity drafts through cracks in walls, under ndoors, and through windows;

·   nAvoid differential pressures on doors, exits, nand windows; and

·   nProvide an opportunity to temper the nreplacement air.

If make-up air is not provided, a nslight negative pressure will be created in the room and air flow through the nexhaust system will be reduced.

HVAC (heating, ventilating, and nair-conditioning) is a common term that can also include cooling, humidifying nor dehumidifying, or otherwise conditioning air for comfort and health. HVAC nalso is used for odor control and the maintenance of acceptable concentrations nof carbon dioxide.

Air-conditioning nhas come to include any process that modifies the air for a work or living nspace: heating or cooling, humidity control, and air cleaning. Historically, nair-conditioning has been used in industry to improve or protect machinery, nproducts, and processes. The conditioning of air for humans has become normal nand expected. Although the initial costs of air conditioning are high, annual ncosts may account only for about 1% to 5% of total annual operating expenses. nImproved human productivity, lower absenteeism, better health, and reduced nhousekeeping and maintenance almost always make air-conditioning cost neffective.

Mechanical nair-handling systems can range from simple to complex. All distribute air in a nmanner designed to meet ventilation, temperature, humidity, and air-quality nrequirements established by the user. Individual units may be installed in the nspace they serve, or central units can serve multiple areas.

HVAC nengineers refer to the areas served by an air handling system as zones. The smaller nthe zone, the greater the likelihood that good control will be achieved; nhowever, equipment and maintenance costs are directly related to the number of nzones. Some systems are designed to provide individual control of rooms in a nmultiple-zone system.

Both the nprovision and distribution of make-up air are important to the proper nfunctioning of the system. The correct amount of air should be supplied to the nspace. Supply registers should be positioned to avoid disruption of emissioand exposure controls and to aid dilution efforts.

Considerations nin designing an air-handling system include volume flow rate, temperature, nhumidity, and air quality. Equipment selected must be properly sized and may ninclude:

·   outdoor air plenums nor ducts

·   filters

·   nsupply fans and supply nair systems

·   heating and cooling ncoils

·   humidity control equipment

·   supply ducts

·   ndistribution ducts, boxes, plenums, nand registers

·   dampers

·   return air plenums n

·   exhaust air provisions n

·   return fans

·   controls and instrumentation n

REFERENCES:

Principal:

1.                      nHygiene and human ecology. Manual for nthe students of higher medical institutions/ Under the ngeneral editorship of V.G. Bardov. – K., 2009. n– PP. 14-34, 71-106.

2.                      nDatsenko nI.I., Gabovich R.D .Preventive medicine. – K.: nHealth, 2004, pp. 14-74.

3.                      nLecture on hygiene.

additional:

1.                      nKozak D.V., Sopel O.N., Lototska nO.V. General Hygiene and Ecology. – Ternopil: TSMU, n2008. – 248 p.

2.                      nDacenko nI.I., Denisuk O.B., Doloshickiy nS.L. General hygiene: Manual for practical studies. –Lviv: Svit, n2001. – P. 6-23.

3.                      nA hand book of Preventive and Social nMedicine. – Yash Pal Bedi / nSixteenth Edition, 2003 –  p. n26-36, 92-97.