We measure length with a ruler, weight with a scale, and temperature with a thermometer, but how do you measure for the colorless, odorless, tasteless, and extremely toxic gas – carbon monoxide.

Carbon monoxide (CO) is a common compound produced by burning fuels, and it can be lethal to humans and pets who inhale too much. Some household appliances emit CO, causing unsafe amounts of deadly gas to collect in the home and poison residents. However, modern warning systems prevent many CO poisonings each year.

A carbon monoxide detector measures for CO in PPM (parts per million molecules of air) and sounds an alarm for dangerous levels. Manufacturers make wall-fitted CO detectors for homes, portable detectors for travel (especially to older hotels), clip-on detectors for wear, and industrial-strength monitors for manual testing.

Official Carbon Monoxide Ceilings

UL2034 is the standard for residential CO detectors in the United States. By design, CO alarms sound faster for higher concentrations of CO, though UL2034 also permits designated CO levels for preset durations to avert false alarms from background emissions.

For the Occupational Safety and Health Administration (OSHA), the permissible exposure limit (PEL) on CO is 50 ppm averaged over 8 hours; levels exceeding 100 ppm require employees to evacuate immediately.

The National Ambient Air Quality Standards (NAAQS) has even stricter CO limits of 9 ppm over an 8-hour period or 35 ppm over a 1-hour period.

Even with three different standards listed, the answer still eludes: how much exposure to this lethal gas is too much?

The Truth about “Acceptable” CO Levels

Though these standards suggest that minimal exposure won’t harm you, you should actively minimize your CO exposure as much as possible.

Many experts believe that the CO levels permitted by UL2034 are still high enough to cause serious health problems. Plus, a CO detector may not activate at all if ambient concentrations wax and wane just outside the alarm limits.

While UL2034 standard CO detectors warn of acute exposure, they might not catch the chronic exposure that still poses serious health risks. Consequently, preventative steps against CO poisoning are a must.

Invest in your own security by investing in CO detectors for your home and for travel. Even in light of the protection they provide, CO detectors are not widely mandated by building codes yet. Nevertheless, CO detectors are lifesavers: they warn people about a deadly gas they would never sense otherwise.

To address chronic CO possibilities, hire a verified air quality professional to “sniff” your premises. Get all gas-burning appliances and fireplaces inspected annually by a qualified technician, or consider replacing them with electric appliances.

Workplaces must adhere to OSHA standards of air quality, and you can anonymously file a complaint with OSHA if you have concerns about CO in your workplace.

Property owners have a duty to ensure residents and visitors are safe from CO exposure. If you or a loved one has been affected by carbon monoxide poisoning, call Wyatt Law Firm at 210-255-2231 for a free case review, or submit a confidential contact form via our website.

Our carbon monoxide attorneys have the experience and expertise needed to tackle complicated CO cases. Let us fight for you.

Read more about CO poisoning on our blog or explore our website.


Carbon Monoxide Kills. (2016). UL2034 – American. Retrieved July 12, 2019, from https://www.carbonmonoxidekills.com/carbon-monoxide-detectors/ul2034-american/

Dwyer, B. (n.d.). How much carbon monoxide (CO) is too much? If you are going to make laws about carbon monoxide alarms, please learn more about it! [PDF]. Carbon Monoxide Safety Association (COSA). Retrieved July 15, 2019, from http://www.cosafety.org/documents/howmuchistoomuch2010.pdf

Flachsbart, P. G. (2008). Exposure to Ambient and Microenvironmental Concentrations of Carbon Monoxide. In D. G. Penney (Ed.), Carbon Monoxide Poisoning (pp. 5-41). Boca Raton, FL: CRC Press, Taylor & Francis Group, LLC.

Hanzlick, M. (2008). Investigating Carbon Monoxide-Related Accidents Involving Gas-Burning Appliances. In D. G. Penney (Ed.), Carbon Monoxide Poisoning (pp. 129-155). Boca Raton, FL: CRC Press, Taylor & Francis Group, LLC.

Johnson, G. S. (n.d.). Carbon Monoxide in Hotels Often Result in Fatalities. Retrieved July 11, 2019, from https://carbonmonoxide.com/carbon-monoxide-in-hotels

Occupational Health and Safety Administration, & United States Department of Labor. (n.d.). 1917.24 – Carbon Monoxide. Retrieved July 12, 2019, from https://www.osha.gov/laws-regs/regulations/standardnumber/1917/1917.24

United States Environmental Protection Agency. (2016, September 08). Table of Historical Carbon Monoxide (CO) National Ambient Air Quality Standards (NAAQS). Retrieved July 12, 2019, from https://www.epa.gov/co-pollution/table-historical-carbon-monoxide-co-national-ambient-air-quality-standards-naaqs