Scientists are looking to reduce covid spread by cleaning the virus out of the air before people can inhale it.
Since the discovery last year that COVID-19 is primarily spread through aerosols, wearing masks in indoor spaces has become the most popular non-pharmaceutical method for preventing viral transmission.
Dr. Paula Olsiewski, a biochemist and contributing scholar at the Johns Hopkins Center for Health Security, said most people don’t think about what’s in the air they breathe, but she’s hoping the COVID-19 pandemic is starting to change that.
“Air, unless the temperature is too hot or too cold or it smells bad, people generally don’t pay attention to it,” Olsiewski said. “When you drink water, are you drinking water that someone else spit out? No. But when you’re breathing air, you’re breathing air that someone else exhaled.”
At the Center for Health Security, OIsiewski has been focusing on air quality in classrooms.
She published a report called “School Ventilation: A Vital Tool to Reduce COVID-19 Spread,” which outlines how schools can create cleaner air through methods like opening windows, adjusting HVAC systems to bring in more outdoor air, upgrading HVAC systems with highly effective MERV 13 filters and placing portable HEPA filtration units in classrooms.
HVAC maintenance and HEPA filters can be expensive. For those who can’t afford to spend much money on filtration, Dr. Kristen Coleman, an assistant research professor at the Maryland Institute for Applied Environmental Health, recommends building a cheaper alternative known as a Corsi-Rosenthal Box. These boxes can be built at home using MERV 13 filters, a box fan, and a couple sheets of cardboard.
“They can really filter out a lot of the aerosol particles, which contain the virus if you have an infectious person in the environment,” Coleman said. “So you can protect the people coming into your business or your restaurant or your classroom.”
Coleman also suggested using a carbon dioxide meter to check whether more ventilation is needed in the first place. The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) recommend indoor carbon dioxide concentrations be maintained at or below 1,000 parts per million (ppm) in schools and 800 ppm in offices.
“And that indicates the ventilation rate. So if the [carbon dioxide] level is too high, then they crack a window,” Coleman said. “And if that doesn’t work as much as they like… then we suggest that you should supplement with [a] portable air cleaner.”
Dr. Jelena Srebric, a professor of mechanical engineering at the University of Maryland, said ventilation, masking and social distancing are all important tools for preventing COVID-19 infection.
She also recognizes that masks can be uncomfortable when worn for long periods of time and proper air filtration can be expensive. Srebric is working on a solution to both of these problems by building a personal air filtration mask she’s calling an air curtain.
Srebric likens the air curtain to the blast of strong air customers feel when entering a big box store. That air keeps the outside air out and the store’s energy bills lower. Srebric’s mask will work in a similar way, preventing air in a room from reaching the wearer’s face.
“We could potentially develop technology that has a small energy footprint … and it’s still much, much cheaper than altering your ventilation system and, hopefully, also much, much more comfortable than if you were in a mask for 16 hours,” Srebric said.
While Srebric said more should be done with ventilation as a way to prevent diseases, she’s glad it’s receiving attention at all. After trying to bring awareness to airborne spread of influenza for the past two decades, she’s thrilled that the public is finally focusing on airborne transmission.
“For me, that was the breakthrough because people who are willing to hear it can now really protect themselves and the rest of them will catch on,” Srebric said.