Because the biggest risk appears to be breath vapor that hangs in the air for relatively short periods of time. Notice I said relatively. In dry, outdoor exposure, the moisture around the particles dries quickly, killing the virus. Indoors, those particles can float for minutes.MavsAg said:
Can someone explain to me why working out at a gym is one of the highest risk activities we can do? I get that if I'm next to someone and we're both breathing heavily then particles will be flying. But if I just go to my own spot of the gym, wipe down my equipment, and keep to myself, what is the harm?
Additionally, the harder people breath, the more particles are "shed" creating effectively a toxic cloud of moist droplets. That cloud moves based on air movement. The direction breathed, people walking, moving, plus air conditioning can help stir the air. Additionally, that toxic cloud also spreads farther given the rate / speed of expulsion. The harder and deeper people breathe, the worse the conditions. The more humid the air (such as in a gym), the longer the virus can survive.
Face coverings, even if not N95, work as a diffuser. Someone who is asymptomatic, or suffering such slight symptoms they don't realize they are infectious will have their breath blocked and kept closer to them. These particles tend to fall faster, reach the floor / ground quicker, and dry quicker. Hopefully, people aren't touching the floor often with their hands, and then touching their face. For someone who is healthy, a face covering helps block the wet particles from entering your mouth and nose. Being trapped, even momentarily on cloth helps dry out the droplets, weakening / killing the virus and reducing the number of virus particles that may enter your body. SARS-CoV-2 isn't like Anthrax, Staph, or papillomaviruses that can survive when dried out. Once its "envelope" dries, it dies.