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Each week, we answer "frequently asked questions" about life during the coronavirus crisis. If you have a question you'd like us to consider for a future post, email us at 

 with the subject line: "Weekly Coronavirus Questions."

I live in a cold (North Dakota) climate and will very soon have to give up outdoor socializing. If I want to try indoor socializing it'll be too cold to keep windows wide open for a long stretch. Would it help to open a window or door for a minute or two every so often? 

Brr! Around the country, as colder temperatures set in, outdoor social gatherings can be harder to swing. Even our dearest friends would find it hard to join us on a snowy, windy backyard picnic or around-the-block stroll.

So from a comfort perspective, it makes sense to consider moving social activities indoors. But you're definitely incurring more risk: The outdoor air can disrupt potentially infectious exhalations. Is there a way to use open windows and air filters and other strategies to make the indoors more like the outdoors?

, an assistant professor of medicine at Duke University, warns that there are limitations to focusing on ventilation via open windows as a way to prevent transmission.

"Ventilation is one of the many interventions we recommend," she says. "All of these measures, from masks to social distancing, work together in symphony. Relying on one alone will inevitably cause gaps in protection."

Those latter two measures — masks and distancing — are probably more important than just ventilation alone, Advani explains. So the best way to minimize risk is to mask up and stay six feet apart.

If you do end up meeting friends indoors — and Advani says you should seriously think about that decision because of the heightened risks of transmission associated with inside spaces — she's not sure how meaningful opening the windows for a short spell every 15-20 minutes would be when it comes to reducing risk. The total effect, she says, would likely be marginal.

Ventilation itself is only really helpful, she argues, when it's highly robust — windows open on both sides of a room to allow for cross-ventilation

and an open, airy space with very few people, for example. Most people can't guarantee that at home. "When we talk about ventilation, what we really care about is air exchanges" or the number of times that air gets replaced in each room every hour. That can be accomplished with a robust air handling system — think airplanes and properly outfitted buildings. But, she says, "there's no controlled way of doing that when opening a window."

, an epidemiology professor at Columbia University, agrees — but adds that some ventilation is probably "better than none." So if you feel inclined to blast open a window in the middle of your North Dakota weather, go for it. Just do so while understanding the severe limitations.

And those limitations? Well, as Morse explains, there are potentially lots of them. For instance: "You can't really tell if the virus is in the air just at the moment when the window is not open — in which case, you haven't gotten much benefit."

Plus, since there's little to no data on this, Morse says it can be hard for experts to give a definitive answer on risk.

"Opening windows and doors intermittently may have some effect on helping with creating more air flow, but the specifics of each room and situation would be different," Harvard Medical School physician 

But one thing is clear, Morse says: "If people are willing to wear masks and commit to social distancing [inside], that will help quite a bit — even [indoors with windows closed] in cold weather."

Does holding your breath while walking by an unmasked (or masked) person help reduce the odds of transmission?

It's every pandemic precautionist's worst nightmare. You've followed all the rules — siloing yourself to your house or apartment and leaving only for a CDC-approved walk around the block.

But what if an unmasked person passes by? And stops to ask you a question?

What if that person is infected and expelling viral particles? Would holding your breath prevent you from inhaling any potentially infectious bits?

Chances are — sorry to report — probably not to a great extent.

To begin with, the chances of transmission from a mini-encounter like the one above are rather small, 

 of Duke University explains. Especially if you're outdoors and you don't stop to speak with the person you're passing.

"Transmission is unlikely to happen in seconds so [holding your breath] likely won't make a difference," Abraar Karan of Harvard says. "If someone just sneezed in front of you, I wouldn't recommend inhaling that — but generally we believe it takes several minutes at least for transmission to occur."

Advani recommends carrying a mask with you to pop on in case a situation like this occurs.

Would spraying some kind of oil — like WD-40 or a silicone or lube-type spray — on the outside of my mask help trap viral particles better? 

When it comes to DIY-upgrades on COVID-19 face masks, our sources are skeptical.

For one, Sonali Advani of Duke University worries about the impact that rubbing such an oil would have on filtration efficiency — the main purpose of a good mask. And there might even be added risks.

"Oil may cause bacteria to grow and affect the filtration process of the mask" she says. "That might possibly increase the risk of bacterial infection."

In general, our sources stress that people should stick to the basics of COVID-19 protection and try not to get too fancy with it.

"The virus itself largely travels within droplets or aerosol particles. Using an oil coating on a mask has not been studied in this manner to have any effect. Altering mask materials could negate efficacy," says Harvard's Abraar Karan.

He concludes, "I wouldn't put an oil coating on a mask."

Pranav Baskar

Author

This week our readers have questions about whether opening windows during winter will make indoor gatherings safer, trying not to breathe during a brief encounter with an unmasked person, and spraying a mask with... oil?

Coronavirus FAQs: Open windows in winter, holding your breath, masks sprayed with oil?

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