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What types of air quality sensors are relevant to COVID-19?

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Natalie Patton

People with respiratory conditions like asthma or those who are allergic to airborne substances like dust and pollen have long been aware of the importance of indoor air quality monitoring. 

The technology has been available for a long time, too, mostly in the form of sensors. With the global pandemic caused by COVID-19 everyone from scientists and device manufacturers to commercial property owners and tenants are taking a closer look at indoor air quality monitoring to see if limiting pollutants can slow the spread of the virus and help buildings become safer places to congregate.

Before we delve into how indoor air quality monitoring and re-calibrating can help in the fight against COVID-19, let’s define the different types of pollutants that can be measured.

Volatile Organic Compounds (VOCs)

Volatile organic compounds are “hazardous compounds that may cause damage to humans with chronic exposure,” according to the National Institutes of Health. The main compounds considered in this category are: benzene, toluene, xylene, ethylbenzene and aldehydes (like formaldehyde and acetaldehyde). These VOCs and others are released into indoor air by natural emissions from human bodies or products within the space, through ventilation systems or other means.

The World Health Organization has established guidelines for “safe” values of these compounds and air quality assessment is often calibrated against those guidelines. There are a variety of VOC sensors available for buildings of various types from office buildings to schools and hospitals.

Carbon Dioxide (CO2)

Carbon dioxide is a naturally occurring gas that in small concentrations is odorless and colorless. In large concentrations, carbon dioxide takes on a distinct acidic odor and can make you feel like you just drank a gulp of soda water. As carbon is the basis of all life on Earth, carbon dioxide is emitted by all living things and thus is the longest-lived and most widespread greenhouse gas present in the atmosphere. At issue today is the ever-increasing concentration of carbon dioxide with nowhere to go.

Though not nearly as toxic as VOCs, elevated levels of CO2 in buildings can lead to loss of concentration, headaches, sleepiness and potentially even temporary loss of decision-making skills which is obviously problematic in buildings that house schools or offices.

Temperature and Humidity

While temperature and humidity are not pollutants, measuring them does work hand-in-hand with monitoring indoor air quality. When indoor spaces are too humid, meaning there is a lot of moisture in the air, harmful substances like mold can easily grow. On the flip side, higher humidity levels is known to reduce the infectivity of common flu viruses because moisture dense air makes it harder for virus particles to persist in the air. The question at hand for scientists today is whether this is true for the novel coronavirus, COVID-19, and if it is, how we should calibrate the air in our indoor spaces to create an more inhospitable environment for the virus to spread. Spaces that have trustworthy temperature and humidity sensors will be able to adapt more quickly to the outcome of these studies.

Air quality in small- and medium-sized commercial buildings

Small- and mid-sized commercial buildings (defined as those that are less than 100,000 square feet) make up 96% of U.S. building stock, but according to research from the National Institutes of Health little is known about the air quality (IAQ) in these spaces. In a small study of 37 small and medium-sized commercial buildings in California back in 2011, researchers found formaldehyde concentrations were above the recommended limits in 86% of the buildings. This was long before COVID-19 and formaldehyde is not a particular factor in the virus, but the point is not many buildings actually monitor their indoor air quality and this is a problem for human health.

While we recommend VOC and CO2 sensors at a minimum, measuring and monitoring just CO2 levels inside a building can be a cost-effective way to assess overall air quality. According to Washington State University’s Energy Program, “the CO2 concentration in an occupied indoor space indicates if the building’s air exchange balance is appropriate – that is, if the optimal amount of outside air (OSA) is being mixed with air that has been circulating in the building.”

The American Society of Heating, Refrigerating and Air-Conditioning, ASHRAE, is unequivocal about this – ventilation and filtration can reduce the airborne concentration of COVID-19. Until there is a coronavirus sensor we can hammer to every wall on every floor of every building in the world, consistent monitoring of VOCs, CO2, temperature and humidity are reliable ways to keep indoor spaces as healthy as possible.

If you’re interested in discussing how our COVID-19 building re-entry solution can help monitor air quality inside your space, give us a call at (888) 684-8454, email us at or fill in the form found here and we will be in touch ASAP. 

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