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CO2 Monitoring and Your Indoor Air Quality

You read the latest news headline that “If you are not CO2 monitoring the air inside your house you are putting your entire family at risk!” then the next article reads, “CO2 monitoring is a hoax!” So that makes it fairly clear on what to do – right. In this post we are going to try and find the common ground.

First, what is CO2 monitoring? CO2 or Carbon Dioxide is what we exhale. A lot of people confuse it with Carbon Monoxide, which is what cars produce. CO2 monitors come in many shapes, sizes and price points but all function in basically the same way. The monitor takes readings of the room and displays the CO2 level of the room in parts per million (PPM). The recommended level inside a home or office should be under 1,000 ppm. Now before you run out and get a CO2 monitor, take a reading in your home and freak out because it is over 1,000, we have more for you to read.

Next, why should I monitor the CO2 level? Many people feel that monitoring the CO2 level will give you a direct reading on what the indoor air quality (IAQ) of the home is. This is not untrue but there are a lot of caveats to it. The principle behind CO2 monitoring is that it will give you an indication of the ability of your home to exchange the air, moving bad things like CO2 and other pollutants out of the home. If you have high levels of CO2 it probably means you have poor ventilation and not enough fresh air coming into the home. You will have a constant flow of CO2 in your home from people breathing. This is going to be elevated depending on how many people live in the home as well as if you host and guests.

Okay, sounds fairly straightforward that every home or office should have a CO2 monitor. While we agree that it would be helpful, this is where we get into the caveats. CO2 is only one of many contaminates in your home. While monitoring the levels is helpful, it is not a be all end all for the IAQ of the home. There are a ton of other contaminates that you also need to be aware of – mold, viruses and pollutants produced from cooking to name just a few. The other issue with monitoring is where you place the monitor. If you place the monitor in the middle of the dining room table as the entire family sits down for a meal, the levels are going to skyrocket. This is because everyone will be breathing directly on the monitor. Conversely if you place it in a closet that is cut off from everything, the levels will probably be very low. Both these scenarios are going to produce inaccurate results.

So now we are back to why would I want to monitor the CO2 when I can’t trust the results? One of the main reasons CO2 monitoring has gained popularity is that it is one of the few indicators for risk of exposure to COVID. Lets make one thing very clear – CO2 monitors do NOT detect COVID in the air. The theory (and we think it is a sound one) is that when dealing with an airborne virus or at least one where the main form of transmission is through the air, you can detect how much air has been exhaled by the level of CO2 in the room. Put another way, if the virus is transmitted from people exhaling, the CO2 level will determine how much air has been exhaled. The other thing we know about viruses is if they are not exhausted or diluted the chanced of transmission increases as more air is exhaled into the room. All of this assumes that someone in the room is a carrier of a virus.

Still not sue about a CO2 monitor. It’s okay, the debate is far from over. CO2 monitors can be a helpful tool but are not going to be the magical solution to your indoor air quality issues. As a matter of fact, they will do nothing to solve IAQ issues. At best they will just let you know you have issues. The route of the problem is how to make sure you don’t have CO2 build-up in your home or office. The good news is that there are very simple answers.

Proper ventilation and a source of fresh air are going to be your best solutions. If you have a CO2 monitor and want to demonstrate this, take a reading inside your car. Next drive in your car with the windows up and no air conditioning or the heat on for about five to ten minutes (like on your way to work or the store) and watch the CO2 level increase significantly. Now open the windows and watch it drop almost instantly. What happens is when you are in your car without any air coming in or going out there is nowhere for the CO2 to go. Once you open the windows, it is quickly exhausted out and fresh air comes in to dilute the level. You are still exhaling the same amount of CO2 just now it is being mitigated. The same principles hold true in your home. Having properly installed and functioning exhaust fans as well as a fresh air source will make your home or office a better place to live or work in. Air King has introduced the Total Home Ventilation System aimed at providing proper ventilation throughout the living space by viewing it as a whole and not as individual pieces. See it in action at

Lets sum all this up. Even with their limitations, CO2 monitors can be an effective tool in determining the level of ventilation and fresh air of a space. They can also be effective at gauging the risk level of a room, especially in a more corporate setting. Using the information gained from the results of the monitor as a piece of the puzzle can help formulate an action plan on how to increase the overall IAQ of the area.

To learn more about ventilation and fresh air solutions visit the exhaust fan, range hood and fresh air sections of the Air King website or view the Air King YouTube channel.

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