If you do not go to crowded places, you can use disposable surgical masks, which need to be replaced after 4 hours of use. Ordinary medical surgical masks are designed to block the spread of droplets, and although they may not protect against haze, etc., they can play a very good role in blocking droplets with large particles. If you are going to a hospital isolation ward or a fever clinic, or an extremely crowded place, it is generally recommended to wear a medical N95 mask, and an ordinary disposable mask is perfectly adequate if it is not a special place. Content source: Dr. You Lai