You’ve likely heard this advice so often that you can repeat it without thinking:
1. Wear a mask.
2. Social distance.
3. Sanitize.
It’s sound science and delivered with effective psychology, following the so-called “rule of three” principle that suggests humans remember information effectively in patterns of three.
But here’s the danger of advice that can be remembered almost mindlessly: You still have to think; you have to apply it to situations. Here in Western New York, with snow totals rising and temperatures dropping, that means making the science work indoors.
Heading into Christmas and the new year, this installment of “Pandemic Lessons” brings you advice from top scientists on how to keep your indoor spaces safe:
People are also reading…
Can’t we just follow those oft-repeated basic rules and be safe?
You can, but you also need to realize that as scientists have learned more about how the coronavirus spreads, some rules have emerged as more urgent than others. For example, though the virus can be transmitted via contaminated surfaces, it’s mainly spreading through the air.
“We need to be spending more than half of our time and efforts and money on cleaning the air, rather than cleaning the surfaces,” said Dr. Lindsey Marr, an aerosol scientist at Virginia Tech who’s done groundbreaking research on the airborne transmission of viruses. “We call it surface hygiene theater: You make people feel safe, because you show that you're cleaning lots of things. But in reality, if you're ignoring the air, then you've missed the big problem.”
Marr and other air quality experts are acutely concerned about aerosols, the microscopic particles we emit when we breathe and talk. An infected person’s aerosols contain virus particles, and if those gather in a room, the other people will breathe them in and possibly become infected, too.
But cleaning the air is tricky. You can spray and wipe down a surface. You can wash your hands. You can even avoid touching your face. But you can’t “spray” the air – at least not safely – and you can’t avoid breathing. Experts note that air cleaning sprays contain chemicals that you don't want to inhale.
OK, clean air is clearly important, but it sounds harder to get. How can you make it happen?
It’s a challenge, but there are multiple strategies you can use:
• Open windows. The essential advice throughout the pandemic is to avoid gathering – especially indoors – with people who live outside your household. But if you do, or if you’re in an office or school, aim for high ventilation by cracking open multiple windows, which exchanges indoor air for clean – albeit chilly – outdoor air.
For this, we can borrow from the advice given to schools that have reopened and seen minimal spread inside the building. In a conference call with reporters before schools opened in late summer, Dr. Joseph Allen, director of the Healthy Buildings Program at the Harvard T.H. Chan School of Public Health, suggested opening windows 6 inches. He said the minimum standard for a safe indoor environment is three air changes per hour, but the typical American school building “gets about half that.” But by opening windows, he added, a school can get double or even triple the minimum air changes per hour. Though the number of air changes will vary from building to building, and from a school or office to a home, you can apply the same principle anywhere.
Marr suggests investing in a carbon dioxide sensor. Since we exhale carbon dioxide, that device effectively hints at the concentration of aerosols in a space. “If the level of carbon dioxide builds up in the air,” she said, “that means you’re not getting enough ventilation.”
• Adjust your air system. If you’re working in a home or office with an HVAC (heating, ventilation, air conditioning) system, adjust it to bring in more outdoor air, rather than mostly recirculating indoor air, which could be contaminated. If your system can handle a filter with a higher MERV (minimum efficiency reporting value) rating, go for it. A MERV 13 filter is ideal, Marr said, because it can remove 80% of virus particles. A typical system, she added, would use a MERV 8.
• Buy a portable air cleaner. Much like a space heater warms a room, a portable air cleaner with a HEPA (high-efficiency particulate air) filter removes more than 99% of virus and other particles, Marr said. “You just need to have enough of them, and a high enough flow rate in the room so that the air is actually passing through that frequently enough that you can remove virus from the air,” she added, noting that limiting the occupancy of a room – and thus having fewer breathing beings in one spot – keeps aerosols down. Masks, too, will limit the aerosols that escape from the mouths of the people who are in the room.
• Get a humidifier — and set it right. Humidifiers are doubly helpful. They are healthy for your immune system: A study by Yale University researchers showed that humidifiers can combat transmission of Covid-19 by bolstering your body’s antiviral response. They also help clear virus from the air — but you need to set it in the right range, said Marr, whose research shows that 40% to 60% humidity is “the sweet spot” where the virus “decays quickly.” If the air gets too saturated with moisture, in the 80% to 90% range, then the virus sits in a respiratory droplet – “its own microenvironment,” Marr said, that resembles what it had in the body. If the air gets too dry, she added, “then the virus actually survives pretty well, like freeze-dried food.”
What are longer-term benefits to better ventilation?
Better indoor air quality is better health.
Marr, who studies these things and tracks other research, pointed out multiple benefits: Kids do better on tests. Workers are more productive. Since flus and colds are transmitted similarly to Covid-19, she said, “We could see a reduction in the number of cases of those other diseases even after we manage to get control of Covid-19.”
Which strategy is the best?
None are failsafe, not even in combination.
Cracking the windows, plugging in a purifier and humidifier doesn’t offer a free pass to host a holiday dinner for 10. But if you want to treat the air with the same care as we do surfaces, these investments are sound ones now and even beyond this pandemic, since they’ll help address airborne issues with a variety of viruses. “People should get both an air purifier and a humidifier,” said Dr. Angela Rasmussen, a Georgetown University-affiliated virologist, in an interview with The Buffalo News this fall.
How do we pull it all together?
Marr likens managing indoor spaces to “being close to a smoker.”
“You don't want to be close to a smoker – you can breathe in lots of smoke,” she said. “As you get farther away, you breathe in less smoke, but that smoke doesn't stop at 6 feet.”
You can distance yourself to 10 feet – “That’s fine, that’s better,” Marr said – but if you’re in that room for a while, and it’s poorly ventilated, you’re still not going to avoid breathing in the smoke.
“That's why we need the distance plus we need the masks plus we need attention to ventilation and avoiding crowds,” Marr said. “So each one of those things help some, but none of them is 100% protective. But when you combine them, then you can get better than 90% risk reduction of the chances of transmission.”
Note: Do you have a topic or question you’d like to see explored in an upcoming installment of "Pandemic Lessons?” Send it to Tim O’Shei at toshei@buffnews.com or via Twitter (@timoshei).
