But many planes have excellent high-efficiency particulate air (HEPA) filters that capture more than 99 percent of particles in the air, including microbes as SARS-CoV-2, the coronavirus that causes COVID. But if you are seated relatively far from others, and everyone is wearing a mask, your risk is probably fairly low. The APTA report suggested that commuters should reduce risk by wearing a mask and staying six feet apart and that train cars should be well ventilated. Mask wearing reduces risk and is now mandatory on many forms of transit in the U.S., including New York City’s subway and bus systems, as well as Amtrak trains throughout the country. There seemed to be less risk of transmission, however, for people who were seated near windows and doors that could open.