Carbon Dioxide

Carbon Dioxide (CO2) is all around us and there is little doubt the air’s CO2 concentration has risen significantly since the start of the industrial revolution. These emissions have dramatically increased within the last 50 years and are still increasing by almost 3% each year. Carbon dioxide emissions are believed to be the most important cause of global warming and are created in large quantities by burning fossil fuels.

Carbon dioxide is a normal constituent of exhaled breath and is commonly measured as a screening tool to evaluate whether adequate volumes of fresh outdoor air are being introduced into indoor air.

The outdoor level of carbon dioxide is around 400 parts per million (ppm). The carbon dioxide level is usually greater inside a building than outside, even in buildings with few complaints about indoor air quality. If indoor carbon dioxide levels are more than 1,000 ppm, when there is inadequate ventilation, complaints such as headaches, fatigue, and eye and throat irritation are often reported.

Although carbon dioxide itself is not usually responsible for indoor air quality complaints, a high level of carbon dioxide may indicate that other contaminants in the building are present at elevated levels and could be responsible for complaints.

Properly ventilated buildings should have carbon dioxide levels between 600ppm and 1,000 ppm, with a floor or building average of 800 ppm or less. If average carbon dioxide levels within a building are maintained at less than 800 ppm, with appropriate temperature and humidity levels, complaints about indoor air quality should be minimized. Therefore, 1,000 ppm should be used as a guideline for improving ventilation. If a building exceeds this guideline, it should NOT be interpreted as a hazardous or life-threatening situation. An elevated carbon dioxide level is only an indication of an inadequate amount of outside air being brought into a building.

Overturning decades of conventional wisdom, researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have found that moderately high indoor concentrations of carbon dioxide (CO₂) can significantly impair people’s decision-making performance. The results were unexpected and may have particular implications for schools and other spaces with high occupant density.

“In our field we have always had a dogma that CO₂ itself, at the levels we find in buildings, is just not important and doesn’t have any direct impacts on people,” said Berkeley Lab scientist William Fisk, a co-author of the study, which was published in Environmental Health Perspectives online last month. “So these results, which were quite unambiguous, were surprising.” The study was conducted with researchers from State University of New York (SUNY) Upstate Medical University.

On nine scales of decision-making performance, test subjects showed significant reductions on six of the scales at CO₂ levels of 1,000 parts per million (ppm) and large reductions on seven of the scales at 2,500 ppm. The most dramatic declines in performance, in which subjects were rated as “dysfunctional,” were for taking initiative and thinking strategically. “Previous studies have looked at 10,000 ppm, 20,000 ppm; that’s the level at which scientists thought effects started,” said Berkeley Lab scientist Mark Mendell, also a co-author of the study. “That’s why these findings are so startling.”

We monitor Carbon Dioxide using an NDIR analyzer. This data provides you with clear information on ventilation rates and indoor activity. When correlated to the health-related pollutants also measured it helps to identify any potential issues for remediation actions and /or advice.