But talking, eating, and other merrymaking don’t magically become safe when they happen inside your home. The coronavirus spreads through the air, so—no matter where you are, even if you’re at your grandma’s house, or your best friend’s—breathing the same air as other people for extended periods of time is risky.
Your best bet is to avoid indoor gatherings altogether. They can be made marginally safer through testing, masking, and limiting the number of attendees, but none of these methods is foolproof. As my colleague Sarah Zhang has written, a negative COVID-19 test is not a “get out of jail free” card; it’s unclear how well the tests work on people who aren’t feeling sick. Masks don’t do much good if people spend several hours together in an unventilated room. And several public-health experts recently told The Washington Post that even small, casual get-togethers are significantly contributing to the spread of the virus.
All of these precautions are flawed; like slices of Swiss cheese, they have holes that let the virus through. But if you layer your Swiss cheese, gathering only in small numbers while wearing masks after being tested, the chance of transmission does meaningfully drop.
The most effective ways to mitigate risk indoors (and again, if you can avoid it, it’s best not to be indoors) might include some approaches that have gotten less attention in the past few months. For example, if you’re inside with other people, limit the time you spend there. A 15-minute visit with a handful of friends is less dangerous than a four-hour dinner party with them.
My colleague Olga Khazan also emphasized that you should consider local transmission rates before deciding whether to see anyone else indoors. As she reported last month, it’s safer (but still not entirely safe) to gather inside if your area is seeing 10 or fewer new cases a day per 100,000 people. Right now that excludes most major metropolitan areas in the United States, as well as plenty of rural counties. But keep in mind that local regulations don’t necessarily map onto local risk. As Amanda Mull has written, just because a business is legally open doesn’t mean you can patronize it safely. Amanda and Annie Lowrey have both written about how state and local governments are allowing businesses to stay open beyond the boundaries of safety because they fear the economic outcomes of closing them.
If you must gather inside, it’s best to make the indoors as outdoorsy as possible. As Zeynep Tufekci wrote in The Atlantic this summer, managing airflow is crucial for curtailing airborne transmission, and it hasn’t received nearly enough attention. Powerful air filtration is the best standard, but even failing that, you can use fans, windows, and your HVAC system to trade as much air as possible between your home and the outside world; here’s a helpful guide for the amateur airflow artiste.