In a gym in Virginia, a carbon dioxide monitor helps the owner, and the gym goers, understand the risk of COVID-19 transmission in that space. Carbon dioxide levels are a proxy for how well-ventilated the gym is and thus how many COVID-19-containing aerosols might be floating around indoor air if someone inside is contagious. If CO2 levels are high, “it means that people’s exhaled breath is accumulating in that room, and their respiratory aerosols are also accumulating,” says Linsey Marr, an expert on the airborne transmission of viruses and a member of that gym who helped it reopen safely. “If someone is infected, those could contain virus.”
Outside, CO2 levels hover around 400 parts per million, and if they’re 800 parts per million inside, “that means 1% of every breath you inhale is from other people’s exhaled breath,” Marr says. “It’s kind of like drinking their backwash.” In Japan, displaying CO2 levels on large screens outside of venues, restaurants, and other public spaces has become a way to communicate COVID-19 risk—and bring something that previously only a maintenance person may have been privy to out into the open.
Since helping her own gym navigate this, Marr has since joined Crossfit’s medical advisory board to help craft national guidelines for gym safety, has gotten requests from places across the country for help with monitoring their indoor air, and has begun carrying a CO2 monitor on her when she goes to an airport or even a grocery store. Marr hopes CO2 monitors stay in vogue and become more common in indoor spaces, even after the threat of COVID-19 has passed. Building ventilation is difficult to assess, and researchers are still learning about its importance to our health. Monitoring indoor CO2 could be an easy way to know when a building needs to improve its air flow.
Researchers are still learning about the potentially harmful effects of indoor air and specifically high CO2 levels. Some research—though small, and inconsistent—has shown high CO2 levels are associated with poorer mental acuity, worsening decision-making skills for office workers and affecting student performance. Aside from that, though, making sure CO2 levels are low could reduce the spread of viruses other than COVID-19. “Other respiratory viruses like flus and colds spread in the same way,” Marr says, “so CO2 is going to be a useful indicator for the risk of transmission of those other diseases.”
The pandemic has also driven new focus and funding into the world of indoor air research, opening conversations about how much fresh air goes into a building and why that’s so important. In March, Honeywell and Syracuse University announced the Honeywell Indoor Air Quality Laboratory at Syracuse University’s College of Engineering and Computer Science, a research partnership to fund better indoor air quality tech. Indoor air quality includes not only CO2 levels, says Manish Sharma, vice president and CTO of Honeywell Building Technologies, but the parameters of VOCs, or volatile organic compounds—gasses emitted from all sorts of solids or liquids—and particulate matter, tiny particles prevalent in both cooking emissions and wildfire smoke that have a host of health effects, along with temperature and humidity.
“It is way beyond the pandemic,” Sharma says of the importance of indoor air quality; It’s about the well-being of a building’s occupants, their comfort, and potentially their productivity. That lab will further study just how much indoor air quality affects productivity and creativity, and how to improve indoor air quality technologies. “During or even after the pandemic, our goal on the air quality side is this subject is going to be as important as maintaining temperature or any parameter inside a building,” he says. “What we believe in is air quality as productivity, air quality as safety, air quality as energy, and air quality as the best environment.”