How Indoor Air Pollution Works

Causes of Indoor Air Pollution

The common household contains many potential sources of indoor air pollutants.
The common household contains many potential sources of indoor air pollutants.

Formaldehyde, PCB, asbestos: These are words that you don't want associated with your living space. Yet odds are that you encounter at least one of these chemicals in your home every day. If not, you're not out of the woods just yet. Indoor air pollutants can be released at high levels in short bursts, like when you use spray paint, or at lower levels over time, like chemicals leaching out of your carpet.

Both the formaldehyde and polychlorinated biphenyl (PCB) mentioned are found in common household products. PCB was banned from production in the U.S. in 1970 but persists in wire coatings, sealants, paints and wood floor finishes. Asbestos, another source of indoor air pollution that has been banned from widespread use, also still lingers in older homes, insulation materials, textured paints and floor tiles.

Formaldehyde is widely used by industries that make building materials and household goods. It is most commonly found in pressed wood products that are used for things like subflooring, shelving, cabinets and furniture, but it is also common in permanent-press fabrics, adhesives and paints.

Let's look at a few of the other causes of indoor air pollution and see where they originate:

  • Radon: often found in the bedrock underneath a home and in building materials
  • Environmental tobacco smoke: the combination of smoke coming from the burning end of a cigarette, pipe or cigar, as well as the smoke exhaled by the smoker
  • Biological contaminants: bacteria, mold, mildew, viruses, animal dander, dust mites, cockroaches and pollen. Many of these grow in damp, warm environments or are brought in from outside.
  • Combustion: unvented gas space heaters, woodstoves, fireplaces and gas stoves emit carbon monoxide, nitrogen dioxide and small particles. More than 3 billion people worldwide continue to rely on solid fuels like wood and coal for their energy needs [source: World Health Organization].
  • Household products: paints, varnishes, hobby products and cleaning products all contain organic chemicals that are released during use and storage
  • Pesticides: 80 percent of most people's exposure to pesticides happens inside; measurable levels of up to 12 pesticides have been detected in indoor air [source: EPA].

The potential for harm from any of these pollutants depends partly on our individual sensitivity. The elderly, the young and those with compromised immune systems tend to be more susceptible. Ventilation also plays a role in how these pollutants harm you. If fresh air frequently circulates throughout the area, the culprits won't have as much time to accumulate and reach dangerous levels. Going back to the bathtub analogy, ventilation is like slowly draining out the oily bathtub water and adding clean water in its place: Eventually, the oil will become less and less of a problem. But if you keep the plug in and do nothing, you're going to have one nasty bathtub ring. Unfortunately, many newer, energy-efficient buildings are practically airtight -- they're like the plugged-up bathtub.

Find out how living in a poorly ventilated, contaminated indoor air space affects you on the next page.