How a mask blocks droplets
00:00:00.000 | Hi, I'm Jeremy Howard from Masks For All, and I've got a quick demonstration here about
00:00:05.440 | why it's so important that you wear a mask.
00:00:08.600 | Your mask protects me.
00:00:10.500 | My mask protects you.
00:00:11.760 | Here's how.
00:00:12.760 | When I speak, tiny droplets of water come out of my mouth.
00:00:16.080 | And I am going to simulate that with a spray bottle.
00:00:18.560 | It's not a perfect simulation because this is actually going to be a lot more spray and
00:00:23.120 | slightly larger droplets even than my talking.
00:00:25.880 | But it's much closer than like an aerosol can, which is explicitly not what happens
00:00:30.000 | when we talk.
00:00:31.000 | They just come out of our mouth at a fairly gentle rate.
00:00:34.200 | So here's what could happen when I talk.
00:00:36.280 | If I spray this close to the mirror here, then as I spray, you can see what happens.
00:00:42.080 | If you zoom in here, you'll see little droplets up here.
00:00:47.080 | So what happens if I step over here and try it with a mask?
00:00:52.760 | So let's do the same thing now with a mask in front.
00:00:57.280 | And this is the place here, and as you can see, zero droplets.
00:01:01.520 | So if I show you this mask, this is the classic T-shirt mask, which actually I haven't even
00:01:09.400 | put the paper towel in the middle, which I often use.
00:01:13.200 | And here's what happens if we use just a paper towel.
00:01:17.840 | Again, if you have a look, no droplets coming through.
00:01:24.020 | So as I said, this is not a perfect simulation of the micro droplets that come out when I
00:01:28.840 | speak, but it's the closest we can get without using special laser-based equipment, which
00:01:34.040 | is what the scientists who have also done this much better than I have used.
00:01:38.280 | But hopefully this explains why it is that if you're not wearing a mask, remember, you
00:01:42.960 | don't know if you're sick because you're most infectious in the early days when you have
00:01:47.720 | no or few symptoms.
00:01:49.760 | So if you don't wear a mask, then those micro droplets are going on your family and your
00:01:54.000 | community members.
00:01:55.100 | So please wear a mask when you make it home.
00:01:57.640 | Thank you.
00:01:58.160 | [BLANK_AUDIO]