Top 20 Indoor Chemical Pollutants

Among the top contributors to indoor air pollution are chemicals that off-gas from many of the products used to construct, furnish, operate and maintain schools, buildings and homes. These chemicals include volatile organic compounds (VOCs), which are emitted or evaporate from these products. Formaldehyde, which is used to make many types of furnishings, is a type of VOC.

Results of studies by the US Environmental Protection Agency(EPA) and other researchers have found that VOCs are common in the indoor environment and that their levels may be ten to thousands times higher indoors than outdoors. In addition, there may be anywhere from 50 up to hundreds of individual VOCs in any one indoor air sample.

At very low levels, some VOCs may produce odors that some people may consider to be objectionable, while others are irritants that can cause people to have headaches and eye, nose and throat irritation, and dizziness. At high concentrations, some VOCs are toxic or may be carcinogenic.

Whether or not someone will become sick or notice an odor is highly variable. Complaints should be taken seriously, however, and investigated. The following tables lists the most common chemical pollutants found in indoor air in general and in schools, specifically:

• Table 1. Twenty of the Most Common Chemical Pollutants Found in the Indoor AIr
• Table 2. Top Chemical Pollutants Found in the Indoor Air, by Concentration
• Table 3. Most Common VOCs Found in Schools

• In more than 3000 air samples collected from offices, schools, and homes, toluene was the most frequently occurring chemical.

• Formaldehyde was present 99 percent of the time at an average level of 0.026 ppm with a maximum of 0.72 ppm.

• Primary VOCs found are associated with solvents, paints and coating, adhesives, cleaners, furnishings, and personal care products.

• For more information on chemicals emitted from specific products, click here or on the Indoor VOCs By Products tab above.

• According to the test results from over 100 schools in the U.S., the average Total VOC (TVOC) level was 276 µg/m3, with a minimum of 1.7 µg/m3 and a maximum of 4599 µg/m3.

• The top 15 VOCs (excluding formaldehyde), of the 345 found in these schools are presented in the table above.

• Most standards and guidelines consider 200 µg/m3 to 500 µg/m3 TVOC as an acceptable level in buildings. Levels higher than this may result in irritation to some occupants. However, lower levels can also be an issue if a particularly toxic substance or odorant is present.

• Additionally, the average level of formaldehyde found was 0.037 ppm, with a minimum of 0.003 ppm and a maximum of 0.121 ppm.

• The World Health Organization and the State of California recommend that indoor exposures not exceed 0.1 ppm, and that actions be taken to reduce levels once they read 0.05 ppm. Although the legal limit covered by OSHA is 0.75 ppm, NIOSH recommends workers not be exposed to more than 0.016 ppm averaged over a 10-hour day.

Data Sources

1. Data supplied by Air Quality Sciences from more than 3000 indoor locations, analyzed by mass spectrometry.

2. Data supplied by Air Quality Sciences from its school test kits.