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Carbon Dioxide Testing in Indoor Air Quality |
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A lot of articles have been written encouraging low levels of carbon dioxide in occupied spaces. Many of the articles, however, either give the wrong impression or don't provide the correct information about how indoor air quality (IAQ) can be impacted by the presence of carbon dioxide.
Carbon dioxide (CO2) is present in outdoor air. It is also a by-product of human breathing. Most importantly, carbon dioxide by itself is not considered a health issue by any of the regulatory agencies until those levels reach as much as 10,000 parts per million (PPM). So why are we so concerned with CO2 levels which fall rise 1,000 PPM?
Indoor air quality investigators use CO2 as a "surrogate" measuring device. Research has shown that as outside air levels (with CO2 levels generally in the 300-450 PPM range) are brought into a building, a mixing or "dilution" of the CO2 levels of the indoor air and outdoor air can be better achieved. By knowing the outside levels and sampling indoor levels, we can determine how much dilution is actually occurring in the space.
The real issue, though, focuses on the contaminants commonly found in indoor environments. Contaminants such as particles from construction activities or dust, gases (from personal care items or cleaning chemicals), and biologicals caused by molds or bacteria, can all be present in the occupied environment. As CO2 levels rise in response to low outside air supplies, so will those other contaminants rise, leading to indoor air quality complaints. Obviously, bringing in outside air to dilute CO2 levels will also help to dilute the other health-affecting contaminants in the space.
Previously, consultants in indoor air quality would state, "Dilution is the solution to indoor air pollution!" Today although we focus on controlling the source of contaminant, dilution makes a terrific second line of defense and can reduce or eliminate many IAQ concerns in commercial buildings. |
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