Indoor Air Contaminants
Microorganisms and Other Biological Contaminants (Microbials): Living organisms and biological matter that can contaminate indoor air and cause allergic or infectious diseases.
- Examples: Viruses, fungi, mold, bacteria, nematodes, amoeba, pollen, dander, mites.
- Sources: Air handling system condensate, cooling towers, water-damaged materials, high-humidity areas, damp organic material, humidifiers, hot water systems, outdoor excavations, plants, animal excreta, insects, food, and food products.
- Acute health effects: Allergic reactions (hypersensitivity pneumonitis, humidifier fever, allergic rhinitis) and infections such as legionellosis. Symptoms may include chills, fever, muscle aches, chest tightness, headache, cough, sore throat, diarrhea, and nausea.
Nitrogen Oxides: A group of highly reactive gases formed during combustion, often seen as air pollutants.
- Examples: Smog components, welding fumes, vehicle exhaust.
- Sources: Gas furnaces and appliances, tobacco smoke, welding, gas and diesel engine exhausts.
- Acute health effects: Eye, respiratory, and mucous membrane irritation.
Ozone: A highly reactive gas with a sharp odor, formed naturally in the upper atmosphere but also produced indoors by electrical discharges.
- Examples: Smog, ozone generators, electrical equipment.
- Sources: Copy machines, electrostatic air cleaners, electrical arcing, smog.
- Acute health effects: Eye, respiratory tract, and mucous membrane irritation; aggravates chronic respiratory diseases.
Radon: A naturally occurring radioactive gas produced from the breakdown of uranium in soil, rock, and water.
- Examples: Indoor radon in basements and poorly ventilated homes or buildings.
- Sources: Ground beneath buildings, building materials, groundwater.
- Acute health effects: None known; chronic exposure may increase risk of lung cancer due to alpha radiation.
Synthetic Fibers: Man-made fibrous materials used for insulation, textiles, and industrial applications that can cause irritation when airborne.
- Examples: Fibrous glass, mineral wool.
- Sources: Manufacturing and use of fibrous glass and mineral wool products.
- Acute health effects: Irritation to the eyes, skin, and lungs; dermatitis.
Tobacco Smoke: A complex mixture of gases and fine particles produced by burning tobacco in cigarettes, cigars, or pipes.
- Examples: Cigarettes, cigars, pipe tobacco.
- Sources: Smoking of tobacco products indoors.
- Acute health effects: Irritates the respiratory system and may trigger eye and nasal irritation, coughing, wheezing, sneezing, headaches, and sinus problems. Contact lens wearers often experience burning, itching, and tearing eyes. Tobacco smoke contains hundreds of toxic substances, including carbon monoxide, nitrogen dioxide, hydrogen sulfide, formaldehyde, ammonia, benzene, benzo(a)pyrene, tars, and nicotine. It is a major contributor to indoor air particulates, most of which are respirable and harmful.
Volatile Organic Compounds (VOCs): A large group of carbon-based chemicals that easily evaporate at room temperature.
- Examples: Benzene, toluene, trichloroethylene, alcohols, pesticides, and solvents.
- Sources: Paints, cleaning compounds, mothballs, glues, photocopiers, duplicators, caulking, insecticides, herbicides, combustion products, asphalt, gasoline vapors, tobacco smoke, e-cigarettes, vaping, dried floor drains, cosmetics, and personal care products.
- Acute health effects: Nausea, dizziness, eye, respiratory tract, and mucous membrane irritation, headache and fatigue.
Knowledge Check Choose the best answer for the question.
2-5. Which of the following are examples of a biological contaminant found in indoor air?
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