As Americans try to build a future of living with COVID-19, one crucial way to protect people from illness is literally all around us: the air.
Research by engineers and public health experts has found proper ventilation can be a key part of protecting people from illness — and not just COVID either.
"There's other types of particles or gases that affect our health," said Linsey Marr, professor of civil and environmental engineering at Virginia Tech. "We know that having good indoor air quality is associated with reduced absenteeism at schools and work, reduced amounts of respiratory illnesses including asthma, and better performance... and better for kids. And then better productivity. So there's a lot to be gained."
The Biden administration did make hundreds of billions of dollars available for ventilation and COVID mitigation for school districts in its American Rescue Plan. The White House also put out guidance for best ventilation practices, but all of that guidance is voluntary. The data around just how much businesses, schools and residences are investing in ventilation is limited.
So how do you do that?
In general, you'd want to get fresh air in and stale air out.
"The idea in all the cases is you have a certain bad actor viruses or the like in the air," said Leon Glicksman, a mechanical engineering professor at MIT. "You want to minimize the concentration by essentially adding more outside air to mix with the room conditions."
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A range of factors can determine how well-ventilated a room is, including the temperature of the air inside or outside a room, amount of space, the number of people in it and what those people are doing, and how the vents are set up.
One solution is installing mechanical ventilation.
This takes an investment of at least a few thousand dollars from your employer or local school district. If done right, fans will collect fresh air from outside, cool it and blow it near the bottom of a room. As people breathe things out into the air, an exhaust fan pulls that stale air up and pushes it back outside.
The effects of mechanical ventilation can be huge. A study of over 10,000 classrooms in Italy found that installing mechanical ventilation in schools reduced COVID transmission. When classrooms had systems that changed out the air in a room every 10 minutes, infections dropped by nearly 75%.
An author of that study, engineering professor Giorgio Buonanno at the University of Cassino in Italy, says the model they developed to figure out air exchange rates and emission can be applied to other settings too.
"With this tool, practically, we can estimate the risk for every kind of scenario," Buonanno said. "Imagine meeting in a room with a volume of 10 persons in the meeting room. You can define the time of the meeting in order to achieve a low risk by fixing the ventilation."
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Another frontier is personal ventilation.
Some people have used portable CO2 monitors, which track the level of CO2 in the air around them. Because humans breathe it out, it can be an approximate but not exact estimate for how clean the air is, and by extension, their COVID risk.
Marr has spent the last several years studying COVID aerosols and says that COVID outbreaks tend to occur when levels are higher.
"Some people like to carry around carbon dioxide monitor sensors like I have, and this is a good indicator of ventilation," Marr said. "The numbers on here tell me the parts per million of carbon dioxide, and for me, I generally look for something below 800 or below 1,000."
If you want to monitor CO2 levels but don't want to pay for a sensor, check with your local library. Public libraries — including ones in Princeton, New Jersey, and Toronto, Ontario, Canada — have offered to let people borrow monitors.
As for filtering air on your own, there are also ways.
Buonanno says he's working on a prototype for a personal air filter that he hopes will specifically blow stale air away from the user. A study published in March in the journal Building & Environment found the filter he helped develop can reduce inhaled particles by between 92 and 99%. He hopes to eventually manufacture an updated version of his prototype filter.
In the meantime, you can build a filter of your own that provides less direct protection but still cleans the air in a given space. Plus, it's cheaper than buying one that often costs $100 or more.
