How To Read A Carbon Monoxide Detector

Unlike fire alarms, a carbon monoxide detector is designed to do more than just sound an alarm at the sign of dangerously high levels of carbon monoxide. Carbon monoxide is a colorless, odorless gas and can kill or cause neurological damage even over long time, moderate exposure. Because of this, it is crucial that you understand how to read your carbon monoxide detector, so you know whether or not carbon monoxide is reaching and staying at dangerous levels in your home.

Step 1 – Getting An Accurate Read

To make sure that the reading on your carbon monoxide detector is accurate, you first need to make sure it is installed in an appropriate location. Most manufacturers will recommend installing near the ceiling. The reason for this is that, while carbon monoxide is close to the same weight as air, it most often comes from fuel burning appliances that will emit warm carbon monoxide. Being warmer, it will tend to rise above the air.

Also, because carbon monoxide is a by-product of any fuel burning appliance, they should not be installed directly above or beside these appliances. They have a tendency to emit a “burst” of carbon monoxide on start up, and may also give an inaccurately high reading because the immediate area around the appliance has more carbon monoxide than the rest of the home.

Step 2 – Understanding The Carbon Monoxide Measurement

Carbon monoxide is measured in parts per million, often abbreviated as PPM, which is a measurement used to describe diluted fluids in water or gases in air. This is a similar measurement to a percentage. For example, one percent (which is one out of 100) is the same thing as one part per hundred. Thus, if one percent of the air in a room was made up of carbon monoxide, that would be equivalent to 10,000 parts per million of carbon monoxide.

Step 3 – Understanding How Much Is Too Much

Obviously, the numbers on your carbon monoxide detector won’t mean much to you if you don’t know how many parts per million is safe and how much is dangerous. While there are no exact concentrations for what you can handle, there are some general guidelines to follow.
As a good baseline for what is safe, 35 parts per million is the maximum concentration allowed by federal law for continues exposure over an 8 hour period. At 200 parts per million, you will experience mild headaches, dizziness or even nausea after two or three hours.
400 parts per million is where it starts to really get dangerous, as you will experience severe headaches after only an hour or two, and it becomes life threatening after more than 3 hours of exposure.

It gets drastically worse from here, with 1600 parts per million causing death in one hour, and 10,000 parts per million causing death in under 10 minutes.

Step 4 – When To Really Worry

One of the important things to remember when checking your carbon monoxide level is that a high number is not always an immediate indicator of a gas leak. For levels up to 200 parts per million, you can leave the home (after turning off all carbon monoxide producing appliances, of course) for a few hours and see if the reading remains the same. Often something as simple as a nearby smoker will cause the reading to spike up to 100 parts per million.

However, if the reading is continuously at or above 35 parts per million, your are at high risk for carbon poisoning and immediate action should be taken, even if your carbon monoxide detector’s alarm is not sounding.