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Monitoring Indoor Air Quality

We have talked at length in previous blogs about indoor air quality and how to improve it, but what about monitoring indoor air quality? As we are beginning to emerge from a long pandemic, we can hopefully retain some of the knowledge gained regarding indoor air quality. While testing for things like flu or COVID in the air is extremely difficult (although there has been some advancement in that area) there are ways to take an educated and fairly accurate guess. When dealing with viruses or something transmitted from person to person, monitoring the CO2 levels of a room can be very effective. There are all types of CO2 monitors but utilizing one that has a digital display of the CO2 level of the room will be the most effective way to monitor it.

We all breathe, it’s kind of important to stay alive. Part of breathing is exhaling. When we exhale we omit CO2. A term that has gained popularity during COVID times is Viral Load. Most scientists agree that there needs to be a certain amount of virus present for it to be contagious (unfortunately at this time we are not sure exactly how much). That is why almost all virologist agree that properly ventilating a room is a very effective way of mitigating transmission. It is also why there are very few cases of transmission in open outdoor areas.

By monitoring the CO2 levels of a room, we can obtain a good picture of potentially how much virus could be in the air. Let’s first look at “normal” levels of CO2. The average level of CO2 in outside air is about 400 PPM (parts per million). Depending on your specific location and the environmental conditions, this will be higher or lower. The average level of CO2 inside a house is between 500 and 1,000 PPM. When you approach 2,000 PPM, especially for extended periods of time, you can start to experience things like drowsiness and even headaches. When you get over 2,000 PPM you start to get into more serious side effects.

So we now have two items – viruses and general concerns about CO2. From a virus standpoint you want to set a baseline CO2 level. For instance, if you test your home on a “normal” day and you get 700 PPM, that is what you want to base any rises in CO2 levels on. This is also effective and maybe even more critical for offices as business get back to in-person workdays. Now during the day as more people are in a given space, if that CO2 level rises you can attribute it to people breathing within that given space. The more people breathing out CO2, the more it will concentrate in the room. With viruses transmitted through breathing, if there is an increased level of CO2, it is logical there will be an increased level of the virus in the air. If you are having a gathering with multiple people in one room or in an office space, you will see a spike in the CO2 level.

As for general levels of CO2, if you have a high concentration, it might be due to malfunctioning equipment/appliances in your home. These should be checked and serviced immediately – especially if you are seeing levels in the danger areas.

Whether rising CO2 levels are due to increased occupancy or factors inside the home, mitigation is typically the same – ventilation. Removing the CO2 from the home or office is critical. Exhaust fans play a critical role in mitigation. Even something like opening windows can have an immediate and positive effect on reducing the CO2 level as well as the virus load within the room. The great thing about these mitigation strategies is you can receive quick, sometimes instant feedback. If your normal level is 700 PPM and you see a rise to 1,500 PPM, by opening a window or turning on the exhaust fan, you should see a decrease. If not, it means the amount of CO2 is building up quicker than you can exhaust or dilute it and other measure may need to be taken (more ventilation, open more windows, reduce the occupancy, etc.).

Monitoring Indoor Air Quality is an effective way to help ensure a health home or office. Visit the Exhaust Fan section of this site for more information regarding ventilation solutions for your home. Also visit the Fresh Air section to learn more about bringing air into your home or office.

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