The best way to protect yourself against air pollution is to wear a PM2.5 filtering mask. Choose masks with filter fabric that has a high PM2.5 filtration rate. For example, ratings such as KN95 and N99 offer high protection (filtering >95% or >99% of PM2.5 respectively). Make sure the mask seals well against your face, preferably with a nose clip, so that polluted air cannot enter around the sides. Note that many dust and surgical masks don’t protect you from air pollution.