Carbon dioxide (CO2)
What it is: Carbon dioxide is a common, colorless, an odorless gas in the air.
Sources in Schools: Exhaled air from humans. Combustion processes such as from vehicles. (Source EPA Indoor Air Quality Action Kit)
Health Effects: Too much carbon dioxide in the air makes it difficult for people to get enough oxygen.
Devices and Measures
Measurement: CO2 can be measured with CO2 monitors. CO2 is measured and reported in parts per million (ppm). For example, 400 ppm means 400 molecules of CO2 in a sample of 1,000,000 molecules of air. The average measure of CO2 in the atmosphere is 420 ppm (March 2023, source NASA).
5,000 ppm
OSHA Permissible Exposure Limit (PEL) and ACGIH Threshold Limit Value (TLV) for 8-hour exposure
6,000 ppm
Peak Carbon Dioxide concentration measured in classrooms from studies reported in Fisk (2017) review of the literature
Source: Fisk, W. J. (2017). The ventilation problem in schools: literature review. Indoor air, 27(6), 1039-1051. https://doi.org/10.1111/ina.12403
40,000 ppm
Immediately Dangerous to Life or Health (IDLH)