I don't disagree that wearing masks seems a good idea, I'm just saying 70% reduction in particles doesn't map to a 70% reduction in transmissions. Whether the r

I don't disagree that wearing masks seems a good idea, I'm just saying 70% reduction in particles doesn't map to a 70% reduction in transmissions. Whether the reduction is 10% or 90%, it's a useful contribution, particularly because in public situations where masks are likely to be recommended (transport, shops) if someone coughs as you're walking past there's no way for contact tracers to know about that link.