City air is a killer. Governments are trying to cut urban pollution by encouraging the use of bikes, but this exposes people who cycle to emissions from the cars of those who don鈥檛. Are anti-pollution face masks the answer?
Fulvio Amato at the Institute of Environmental Research and Water Assessment in Barcelona and his colleagues have tested nine commercially available masks aimed at cyclists for filtering out air pollution. The best screened out nearly half of the most harmful tiny particles that cyclists breathe in.
Air pollution has been linked to respiratory and cardiovascular disease, diabetes and cancer. It may also harm unborn babies and impair cognitive function in children and adults. In 2014, the World Health Organization estimated that air pollution was a factor in 7 million premature deaths worldwide each year.
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One of the nastiest things swirling around in city air is particulate matter 鈥� small particles spat out in exhaust fumes, or tiny fragments of car tyres, brake pads or road surfaces that are shed through wear and tear. Particles less than 2.5 micrometres in diameter, known as PM2.5, can damage the lungs and even enter the bloodstream.
Amato鈥檚 study is the first to test face masks designed for cyclists in an urban environment rather than the lab. The team fitted the masks to dummies and exposed them to inner-city traffic in Barcelona. To simulate the increased respiratory rate of a cyclist, the dummies sucked in air at three different speeds.
The best mask reduced the intake of PM2.5 by 48 per cent. It had a filter with three different layers that covered its entire inside surface. The mask was also a better fit to the dummy鈥檚 face than the others. The worst mask only had filters over two air intake valves and did not fit well.
Beards beware
If a mask doesn鈥檛 fit properly it becomes ineffective, says Gary Fuller at King鈥檚 College London, who wore a professionally fitted mask to protect against asbestos in a previous job. 鈥淎nyone who works in a hazardous environment knows you have to get the seal right,鈥� he says.
Even opening your mouth to breathe can affect the seal. 鈥淎ny leaks and it doesn鈥檛 work,鈥� says Fuller. 鈥淎nd if you have a beard, just forget it.鈥�
Cycling masks are also no good against harmful gases, such as nitrogen dioxide. 鈥淐hemical filters exist but they are much more expensive,鈥� says Amato.
Wearing a mask won鈥檛 do you any harm. But Amato recommends simply avoiding rush-hour traffic and busy roads. If there is a cycle path by the side of the road, it makes sense to use it. 鈥淒istance from the road edge makes a great difference,鈥� he says. 鈥淓ven a few metres significantly decreases exposure.鈥�
Fuller agrees. His team has helped to identify less polluted paths around London. The data went into developing an online tool called the Clean Air Route Finder which suggests low-pollution routes between locations based on air quality readings for the day. Other apps exist for other parts of the world.
Despite the pollution, cycling around a city is still far better for your health than driving 鈥� whatever the route. You are probably exposed to less air pollution on a bike than in a car because in a car you sit directly behind other exhausts, says Fuller. Several studies have also found that the benefits of physical activity more than compensate for the negative effects of pullution, he says.
Science of The Total Environment
