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Indoor Air Pollution |
STOP - You must read Chapter 12 before doing this lesson
Introduction
Indoor air pollution as an environmental problem has been receiving increasing attention in recent years. Indoor air pollution is usually a greater direct threat to human health than outdoor air pollution. In 1990, the EPA ranked indoor air pollution as the most important environmental cause of cancer. Indoor air pollution is such a threat to human health for two main reasons. First, the indoor environment tends to concentrate pollutants. Some toxic and cancer-causing pollutants can reach air concentrations that are 100 times greater than outside air. Second, on average, people in industrailized societies spend more than 80% of their lives indoors, including time spent in offices on the job. Sick building syndrome is a popular medical term that refers to chronic ailments such as headaches, nausea, allergic reactions, and other symptoms that are caused by indoor air pollutants where we work or live.
Sources and Types of Indoor Pollutants
There are many sources and kinds of indoor air pollution, but the vast majority of harm is cause by radon and second hand smoking. The two major types of contaminants are chemical and biological contaminants.
 | | Radon gas points of entry |
Chemical contaminants can be either gases (e.g., carbon monoxide, nitrogen dioxide) or particles (e.g., aerosol). Some common household sources of chemical contaminants include oil and gas appliances, tobacco smoke, paints, and pesticides. Biological contaminants originate from living things or are themselves living things. Sources of biological pollutants include humidifiers, air conditioners, mattresses, pets, and carpets. In nearly all cases, the harmful effects of indoor pollution can be greatly reduced by increasing ventilation in a building.
- Radon - Radon gas, which is the most harmful indoor air pollutant when found in high concentrations, generally enters the home through underground diffusion. Radon is radioactive and may lead to lung cancer due to inhalation of radioactive particles that become lodged in the lungs.
Radon web site. Learn more about radon.
EPA web site on radon.
Air Quality Program: Radon
- Combustion: Especially Smoking -
Stoves, fireplaces, and heaters are common appliances that emit air pollution from combustion. Remember that carbon monoxide is a poison caused by incomplete combustion; it can cause headaches and even be lethal in closed areas where stoves or heaters are not functioning properly. The most harmful combustion source of indoor air pollution is tobacco smoke.
- Chemical Emissions: Source of Many Pollutants - Chemical emission can come from dozens of sources indoors. Many of these chemical emissions are carcinogenic but only in concentrations that are generally much higher than occur in the large majority of homes. However, they can cause headaches, dizziness, and nausea, specially in people with allergy reactions. Mothballs, bleach, shoe polish, cleaning solvents, air freshners, and many other chemical products emit gases that can be toxic if they concentrated by poor circulation. Many materials release carcinogenic fumes, such as benzene and formaldehyde. Benzene is emitted by plastics, synthetic fibers, and cleaners; formaldehyde is emitted from foam insulation and wood products such as particle board, plywood, and some glues.
EPA web site on indoor air pollution.
Air Quality Program: Indoor Air Pollution
Indoor Air Quality: People and Health
Air Pollution Control
Air pollution control have improved tremendously since the implementation of the Clean Air Act in 1970. The major emphasis have been in reducing stationary and mobil souce emissions. To control the emissions of mobil sources (automobiles) catalytic converter are use. They work by converting the carbon monoxide, nitrous oxides, and hydrocarbons into carbon dioxide, nitrogen and water. Automobiles also, recirculated exhaust gases. This two process greatly reduced auto emissions.
Stationary sources can use different technologies to reduce air pollution. To control particulate matter they can used filters, baghouses, cyclone precipitators, and electrostatic precipitators. For power plants that use coal, the main problem is the sulfur dioxide it produces upon burning. Some solutions to this problem are:
- Burn only low sulfur coal.
- Wash coal to remove pyrite.
- Gasification - convert coal to gas to removed sulfur.
- Limestone injection - mix coal with limestone, to form calcium sulfides or sulfates, which prevent sulfur from forming sulfur dioxide.
- Scrubbing - slurries of lime or limestone.
EPA web site on air pollution control.
