22-06-2011, 10:11 AM
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1. INTRODUCTION
In many people’s mind air pollution is associated with contamination of urban air from automobiles exhaust and industrial influents. But every year the indoor air pollution is responsible for the death of 1.6million people ,that is a death in every 20 second .Exposure is high among women and children who spend most of their time near the domestic hearth .
The severity of indoor air pollution is aggravated by the fact that the more than half world’s house wife cook their food on unprocessed solid fuels , buildings are built more air tightly to save money spent on heating and cooling .At the same time people are using more and more irritating products such as hair spray , other cleaning detergents pesticides and other which are harmful to health.
Indoor air pollution is the presence of one or more contaminants indoors that
carry a certain degree of human health risk. Indoor air issues may be traced to the beginning of civilization. Prehistoric records note the problem of smoke in caves. However, over the last three decades the public has become more aware of indoor air pollution. Various studies show that people spend 65 to 90 percent of their time indoors; 65 percent of that time is spent at home. Field studies of human exposure to air pollutants indicate that indoor air levels of many pollutants may be two to five times, and on occasion more than one hundred times, higher than outdoor levels.
2.INDOOR AIR POLLUTION
Indoor air pollution is the presence of one or more contaminants indoors that carry a certain degree of human health risk. Indoor air issues may be traced to the beginning of civilization. Prehistoric records note the problem of smoke in caves. However, over the last three decades the public has become more aware of indoor air pollution. Various studies show that people spend 65 to 90 percent of their time indoors; 65 percent of that time is spent at home. Field studies of human exposure to air pollutants indicate that indoor air levels of many pollutants may be two to five times, and on occasion more than one hundred times, higher than outdoor levels.
2.1. INDOOR AIR QUALITY ( I.A.Q )
It is the term refering to the air quality within and around buildings and structures , it is related to the health and comfort of the building occupants.IAQ can be effected by microorganisms,gas,particulates or any mass or energy stressor that can induce adverse health conditions.Indoor air is becoming an increasingly more concerning health hazards than outdoor air.(1)
Fig2.1 Air pollution sources in house
3.COMMON POLLUTANTS
The four principle sources of pollutants of indoor air.
1.Combustion.
2.Building materials.
3.The ground under the building.
4.Biaerosols.
In the developed countries the most important indoor air pollutants are thecompustion products.Radon,asbetos ,volatile organic compound , pesticides , heavy metals animal danfe mits , moulds and environmental tobacco smoke.
In developing countries the pollutants are combustion productos of unprocessed solid biomass fuel used by the poor urban and rural folk for cooking and heating .A recent report of WHO states the “Rule of thousands”.Which states that a pollutant released in indoor is thousand times more likely to reach peoples lung than a pollutant released outside.
3.1 Radon
It is a invisible , radioactive atomic gas that result from radioactive decay of radium ,which may be found in the formation beneath buildings .It will tend to accumulate at the floor level.These deposits in the lung of the occupants either directly or by ataching to air born particles , which are then inhaled . To dilute the way that they occur from nature deacay , ventilation is provided.
3.2 Molds and Allergens
These biological chemicalscan arrise from a host of means , but there are two common classes
• moisture induced growth of mold colonies
• natural substances released from animal clander
Moisture buid inside the home may arise from the water penetrating compromised area of the building envelops and the skin , plumbing laeks , from condensation due to improper ventilation or from the ground moisture penetrating into the building parts.In the area where the cellulosic material fail to dry witin 48 hours , mold mildew can propagate and release allergenic spores into the air .Indoor mold growth can be inhabited by keeping humidity level below 50% and eliminating any water leak.
3.3 Carbon monoxide
A clourless , odourless , gas that is a by product of incomplect compustion of fossile fuels . Common source of carbon monoxide are tubacco smoke,space heaters using fossile fuels ,defective central heating furnances and automobiles exhaust .Indoor carbon monoxide levels may rise aout 25-35 ppm.(4)Current ventilation standard recognise that significantly more air flow is needed in smoking areas than in the non-smoking area .This need is based primarly on achieving acceptable odour level than controlling carbon doixide level.
3.4 Volatile organic compound (V.O.C)
It is emitted as gas from the certain solid or voc are emmited by a wide array of products such as paints , varnish , pesticdes , building materials and furnishing , office equipments such as copier , printer correction fluid , carbonless copypaper,graphics and craft materials including gluye ,permenent marker , photographic solutions.Testing emmision from building materials used indoor has been increasing commenly for floor level , paint.
3.5 Legionella
It is a water born bacterium that grow best in slow moving or silt water.The primary route of exposure is aerosolation ,most commenly from evaporative cooling or showerhead . It is mostly found in commercial building is from poorly placed or maintained evaporative cooling tower , which often release aerosolzed water that may enter near by ventilation intake .Outbreak in medical facilities and nursing homes where patients are immuno-supressed . The reason is legionella .Prevention measures include adjusting normal hot water level to allow far for 120 degreeF at the tap , evaluating facility design lay out , removing favect aerators and preiodic testing in suspect area.