Do those pollution masks actually work?

我们把特蕾西的问题到莎拉·马登,从剑桥市ridge University... Sarah - That’s a really good question. It’s become more relevant as pollution in places like London has become quite bad recently and there’s over 10,000 deaths just in London and the UK every year. This kind of question becomes more and more relevant to us. Actually it’s kind of yes and no. Those face masks that you often see people having in Beijing (the surgeon’s masks) they do pretty much nothing. They aren’t airtight so they will pretty much let anything in and there’s not any point in using them. There are more advanced types of masks like gas masks that you're used to seeing… Chris - the fit tested masks? Sarah - Yeah that kind of thing. Chris - They do form a proper seal around your mouth. Sarah - They do stop particles getting in but often you can still breath in the gases and that can be a problem because nitrogen dioxide is one of the really harmful things in the polluted cities. It causes your lungs to become inflamed and causes you to develop bronchitis and that’s harder to block getting in than those find particles that you’d get. Andrew - So, as somebody who works in London next to one of the busiest, most polluted streets there is - it really is really bad. Is there anything that I can do that would help? Sarah - One of the best things you could do is almost to choose less congested routes. So if you were a cyclist go around the back streets if that’s possible. I think, if you have these masks, it can be quite hard to breath so it’s not good for cycling. Chris - We did make a programme on this last year, Andrew, and we actually sent one of our team to London to wander around various places wearing a set of sensors that were developed here in Cambridge and also at King's college in London to do ambulatory air quality monitoring. And the worst place in London we found was to get in a taxi because you’re in the thick of the traffic and all of the fumes are being pulled in from the car in front straight into the taxi and they can’t blow away because you’re in this sealed glass container. Best thing actually is to go down by the river, so take a stroll at lunchtime down by the Thames and it’s less polluted there we found. Actually, there’s even a difference between walking along the kerbside next to the road and if you move as far from the road edge as you can. So the advice would be avoid London, avoid getting in a cab in London, and go for a walk by the Thames if you want to. Sarah… Sarah - I was just wondering if any of those masks had any effect on microbes like bacteria or viruses because that’s what a lot of people often wear those masks for when they’re on the tube or something like that? Sarah - That’s a really good question. Microbes sit, in terms of size, in between a particle of dust you’d get from a car, and gas molecules are somewhere in between, and I guess it would be borderline whether they could stop that. Chris - Yeah. In hospital we don’t think they work when we use them for infection control because you often say let’s put a person who’s got an infection, let’s put one of those on them. And, as far as we know, as soon as they get wet because of breath dampening the material the bugs can go straight through and also, as you said Sarah, they’re not sealed round the edges. You just blow them all out the sides. Also, when people wear them to protect themselves they don’t protect your eyes and your eyes are connected to your nose, so all the bugs that land on your eyes get washed into your nose and affect you via that route. Sarah - Yeah. Chris - So you’re actually better off just staying at home and become a hermit. That’s the best solution.