Definition and principal sources
Carbon dioxide (chemical formula CO2) is a naturally occurring in earth’s atmosphere as part of the Carbon Cycle (Natural circulation of carbon amoung the atmosphere, oceans, soil, plants and animals). Ordinarily it is not poisonous. However human activities are altering the carbon cycle by adding more carbon into the system principally through the burning of fossil fuels.
Research has documented direct health effects of CO2 on humans, but only at concentrations much higher than found in normal indoor settings. Varied adverse effects exist at differing levels of CO2 concentrations.
- Deepened breathing is caused by concentration greater than 20,000 parts per million (ppm),
- Respiration markedly increases above 40,000 ppm,
- Visual disturbances, tremors and loss of consciousness have been associated with above 100,000 ppm and,
- Death can iccur above 250,000 ppm (25% CO2 in atmosphere).
Epidemiologic and intervention research has shown that higher levels of CO2 within the range found in normal indoor settings are associated with perceptions of poor air quality, increased prevalence of acute health symptoms (e.g., headache, mucosal irritation), slower work performance, and increased absence.
Recommeded exposure limits
Maximum recommended occupational exposure limits for an 8-hour workday are 5,000 ppm as a time-weighted average, for the Occupational Safety and Health Administration (OSHA) (OSHA 2012) and the American Conference of Government Industrial Hygienists (ACGIH) (ACGIH 2011).
EPA – Carbon Dioxide Emissions