Personal research, but the way I see it, if there’s a 10 or 20% chance wearing a mask prevents me spreading something to others, I wear a mask. That’s just common decency. Glad you see it similarly.

If you really get into the guidance, it’s 95% mask compliance that experts say would pancake the curve. If it’s 70% including liars, it isn’t enough, especially as people migrate into indoor gatherings. And if a bunch of masked people cram into a poorly ventilated room, things will still spread.

So it’s not the only important step, but to really get to the truth of mask effectiveness taken alone, you’d need greater compliance than the likely French real number of 60-65%.