What happens when those droplets start to evaporate?
What happens when people use the same mask over and over again?
Both good questions. Mostly, as the droplets evaporate, they stay airborne longer and eventually stick to something (you or another surface). Drying out completely will often kill the virus. If you reuse a mask that cannot be washed, it may start out contaminated or you might leave it sitting around long enough that the virus is destroyed. I leave mine in the sunlight for a week before reusing.