CO Levels of Concern in Government Recommendations
and Regulations, in Voluntary Industry Standards, and
in Physiology, Public Health and Veterinary Practice
Information compiled by Albert Donnay.
Reposted on 2/17/2011 with permission from coconundra.info
All CO levels below are stated in parts per million (ppm) unless otherwise noted.
World Health Organization (WHO) standards are published in mg/m3.
For those who want to do the conversion, 1ppm = 1.145 mg/m3 and 1mg/m3 = 0.873 ppm.
For those who don’t, remember that any level in mg/m3 is about 10% less when expressed in ppm.
- Levels in white refer to average outdoor CO levels
- Levels in red refer to US EPA, US OSHA and WHO regulatory limits
- Levels in blue refer to recommended exposure limits of ACGIH, ASHRAE, and NIOSH
- Levels in yellow refer to US and European consumer CO alarm standards
- Levels in green refer to exhaled breath ranges
- Levels in white refer to guidelines of the Baltimore City Fire Dept, which are typical of most FDs
0.1-1 = level of increases in average outdoor CO–within current outdoor ranges of 0-5 ppm– that are associated in over 100 epidemiological studies with significantly increased risks of mortality and morbidity from many cardiovascular and respiratory disorders and, in growing fetuses, with low birth weight and birth defects–even after adjusting for the effects of other pollutants (ozone, SO2, NO2 and particulates) in multi-pollutant analyses.
9 = max 8-hour avg outdoor ambient CO level allowed by US EPA, unchanged since first adopted in 1971.
UL2034 to continuously display the actual CO level.
30-50 = lowest CO range in which consumer CO alarms are required by European Norm standards (EN50291) to sound, but only after this level has been continuously sustained for 2 hours.
30-70 +/-3 = lowest CO range in consumer CO alarms are required by UL2034 to sound, but only after this level has been continuously sustained for over 30 days. This is meant to (and effectively does) insure that consumer CO alarms never provide any warning at CO levels below 70ppm.