Causes and Sources of Indoor Air Pollution

The Most Common Indoor Air Pollutants

What kinds of materials can get into your home’s air? More than you might think! Some 900 different pollutants have been found in indoor air. Here’s a list of the most common kinds and categories of indoor air pollutants and the places they come from:

  • Carbon Monoxide is an invisible, odorless, and tasteless gas produced by the incomplete burning of carbon-based fuels like gas and oil in devices like furnaces, gas ranges, and non-electric space and hot water heaters.
  • Combustion by-products (CBPs) are gases and particles created by cigarette smoking, fireplaces, woodstoves, furnaces, gas ranges, and non-electric space and hot water heaters.
  • Dust is being made around us all the time as the materials we use in our daily lives break down and shed microscopic particles. Believe it or not, the average 6-room home accumulates roughly 40 pounds of dust each year, and there’s not much we can do about it. Household dust can contain tiny pieces of textiles, wood, and food; mold spores; pollens; insect fragments; furs and hairs; and particles of smoke, paint, nylon, rubber, fiberglass, plastic, and paper.
  • Formaldehyde is a chemical used in everything from carpet and pressed wood products like plywood to bed linens. Formaldehyde is a volatile organic compound, and it’s so common that some experts believe it to be the single most important indoor air pollutant. For this reason, it warrants a separate mention among the many hundreds of VOCs that can exist in indoor air. Formaldehyde is a colorless gas with a sharp odor, although at the concentrations typically found in indoor air, it is undetectable by our sense of smell. Leading sources of formaldehyde include the resins and glues found in paneling, doors, furniture, wallboard, ceiling panels, and pressed-wood products like particleboard and plywood. Other sources include carpets, decorative wallpapers, and fabrics in which formaldehyde is used as a finish to create permanent press, flame-resistant, water-repellant, and shrink-proof materials. Formaldehyde can also come from gas stoves, glues, room deodorizers, cosmetics, personal care products, paper grocery bags, waxed paper, paper tissues and towels, and even feminine protection products.
  • Nitric Oxide and Nitrogen Dioxide (Nitrogen Oxides) are colorless, odorless, and tasteless gases produced by gas ranges.
  • Ozone is a gas created by the breakdown of volatile compounds found in solvents; by reactions between sunlight and chemicals that are produced by burning fossil fuels; and by reactions between chemicals found in materials like paint and hair spray. Most ozone in the home comes from outside, predominantly from automobile exhaust. For this reason, ozone is more problematic in urban and suburban homes. Ozone can also come from copy machines, laser printers, and ultraviolet lights.
  • Particulates are tiny particles of soot and other materials. The biggest sources of indoor particulates are windblown dust from outside, house dust, and tobacco smoke. Secondary sources include wood stoves and appliances like furnaces and non-electric heaters.
  • Pesticides are chemicals intentionally designed to kill. Whether sprayed or applied in other forms, pesticides easily become airborne and can spread throughout the house far past the point of actual use, polluting both the home and its occupants.
  • Radon is a natural radioactive gas that seeps from the rocks and soil surrounding certain homes. Radon is odorless, colorless, and tasteless and largely a problem only in basements in regions where soils have a large radon content.
  • Tobacco smoke is a mixture of over 4,700 different chemical compounds and the single most  reventable indoor air pollutant on this list.
  • Volatile Organic Compounds are carbon-based compounds that form vapors at room temperature. In the home, the presence of these chemicals in the air comes predominantly from two sources: the outgassing of synthetic materials like foams and plastics and the use of toxic cleaning products and other household chemicals. Common VOCs include benzene, toluene, xylene, vinyl chloride, naphthalene, methylene chloride, and perchloroethylene. But such materials are just the tip of the VOC iceberg. There are hundreds of VOCs capable of causing all kinds of illnesses and ailments.


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