Chat with us, powered by LiveChat

Unhealthy Carbon Monoxide Levels May Exist In Your Home Despite Detector Not Going Off

December 26, 2019

Did you know that Carbon Monoxide (CO) exists in your home? Many of my clients will act surprised since their home detector has not gone off. You and your family could be exposed to low levels of chronic carbon monoxide that is not being detected by your home CO detector. Even if you have a carbon monoxide detector that has a digital display reading of zero, the actual level of carbon monoxide is not zero. In fact, the CO in your home could be as high as 150.0 parts per million (ppm) for 50 minutes and still read zero according to CO alarm standards developed by Underwriters Laboratories (UL2034) in collaboration with the US Consumer Product Safety Commission.

Why is this allowed?  I can’t get a straight answer but speculate that if people saw readings on their CO detectors higher than zero then they would call the fire department creating an unmanageable need to verify the CO levels in all homes at all times.


  • Dull headache.
  • Weakness.
  • Dizziness.
  • Nausea or vomiting.
  • Shortness of breath.
  • Confusion.
  • Blurred vision.
  • Loss of consciousness

What Levels Are Safe?

Ok, so what level is safe? We contend if your home is properly ventilated and appliances working as they should then your carbon monoxide levels should be comparable to outside. Typical levels outside will vary between 0-2ppm.  We define levels below 3.0ppm in the normal zone, safe and comparable to most homes tested.  Generally, the levels outside are generally higher in summer and lower in the winter.  Homes that are well insulated, spray foamed, or too tight trap toxic pollutants including dangerous gasses like carbon monoxide.

At IndoorDoctor, 0ur fully calibrated meters will record the carbon monoxide in your home down to 0.0 parts per million to provide you true peace of mind as to the healthiness of your home regarding CO.

Why Regular Furnace Inspections Matter

Agency Exposure Limits
OSHA PEL (General Industry) 50 ppm TWA
EPA TWA 9.0 ppm TWA
ASHRAE 9.0 ppm TWA
NIOSH REL 35 ppm TWA; 200 ppm Ceiling
NIOSH IDLH 1,200 ppm
  • TWA = Time Weighted Average exposure concentration for a normal 8-hour workday and 40-hour workweek
  • STEL = Short Term Exposure Limit (Usually a 15-minute time-weighted average exposure that should not be exceeded at any time during a workday
  • NIOSH (National Institute for Occupational Safety and Health)
    • REL = Recommended Exposure Limit
    • IDLH = Immediately Dangerous to Life or Health Concentration
  • OSHA (Occupational Safety and Health Administration)
    • PEL = Permissible Exposure Limit
  • ACGIH (American Conference of Government Industrial Hygienists)
    • TLV = Threshold Limit Value
Learn More

Blog Form

By checking this box you agree to receive SMS communications from IndoorDoctor. Reply stop to opt-out at any time.