@NuritBaytch @Don_Milton @kprather88 It probably did. Low air concentration and a quite good respirator (he says passed fit test) would be very unlikely to fail. But hopefully theory plays out in practice. Plus source w/KN95 is a plus.
Good vent/filt plus respirator is the only situation where I feel risk is "low".
@NuritBaytch @Don_Milton @kprather88 它可能做到了。低空气浓度和非常好的呼吸器（他说通过了适合性测试）不太可能失败。但希望理论在实践中发挥作用。带 KN95 的加源是一个加号。
良好的通风口/过滤器加呼吸器是我认为风险“低”的唯一情况。