Smoke from wildfires in Canada is blowing in to major Eastern US cities and can cause real injury. To be safe, wear an N95 mask.

You can get partial protection outdoors by wearing an N95 mask. An honest KN95 works equally well; the problem with KN95 is that China does not attempt to certify each brand and each model. As a result, many kinds of KN95 masks are fake and won't protect at all.