N95 respirators are the gold standard for keeping COVID-19 at bay. But as with so many things, there’s a right way and a wrong way to use them. Here’s expert guidance from the CDC, in English, and translated into Simplified Chinese, Spanish, Korean and Vietnamese, on how to use an N95 mask correctly. Also included: a reminder that patients with heart and lung problems should consult with a doctor before using an N95, because they can make it harder to breathe.