Normal Levels of Carbon Monoxide in a Home

Leah Waldron-Gross

In the U.S., about 170 people die each year from prolonged exposure to carbon monoxide in the home. The levels of carbon monoxide, or CO, in your home will vary if a gas stove is present and properly adjusted, according to the Environmental Protection Agency (EPA).

Average Parts Per Million

If you own a gas stove, the average CO level in your home will range from 5 to 15 parts per million (ppm). If your gas stove is poorly adjusted, the average CO reading is closer to 30 ppm or higher, which can cause dangerous reactions if the problem remains unresolved. In homes without a gas stove, CO levels average between .5 and 5 ppm.

High Level Reactions

An abnormal level of CO cannot be detected by human senses, as it is colorless and odorless. However, low- to moderate-level exposure, which includes CO level readings over 70 ppm, can cause non-fever, flu-like symptoms such as headache, fatigue, shortness of breath, nausea and dizziness. If CO levels are high, which includes prolonged exposure with a 150 to 200 ppm reading, symptoms may include vomiting, muscular coordination loss, mental confusion, loss of consciousness and death. Humans can withstand between 1 and 70 ppm carbon monoxide exposure without reacting to it, although heart patients may feel chest pain.

Carbon Monoxide Detectors

CO detectors are required by law in many states. The Consumer Product Safety Commission recommends that every home install a CO detector for safety. Detectors have an alarm that is programmed to sound if the CO levels in your home exceed 70 ppm. CO detectors should be installed in every bedroom of your home and each interior hallway but not in the kitchen or near heating appliances, CPSC states.

Preventing Abnormal Levels

To prevent abnormal levels of CO in your home, the EPA recommends adjusting your gas appliances regularly, opening your fireplace flue while it's in use, avoiding letting your car idle in the garage or using a generator indoors, installing an exhaust fan over gas stoves and only using wood stoves that meet EPA emissions standards. If you are using a space heater, choose a vented model, and make sure to use the right fuel type when filling a kerosene space heater. At least once a year, you should hire a professional to inspect your home's central heating appliances and repair or clean any problems or leaks.