¿El peligro y la contaminación rebasan los beneficios en salud del ejercicio?
Anyone who spends much time on a bicycle in a city, dodging diesel-belching buses and wayward motorists, has wondered at some point whether the overall health benefits of cycling are gnawed away by pollution exposure and the risks of being killed or seriously injured. The facts, as the data journalists of the UK’s Financial Times Magazine explain, are somewhat reassuring: Unless you live in a small handful of extremely polluted cities, you should get on a bike.
The FT team looked most closely at London, which is safer for cyclists than most U.S. cities, with an average of 1.1 deaths per 10,000 bike commuters. New York City, by comparison, has 3.8 fatalities, which is at least safer than Sydney, Australia, with 8.3. (The safest big city for cyclists: Copenhagen, Denmark, with a mere 0.3 fatal crashes for every 10,000 daily commuters.) U.S. figures on bicycle fatalities from the National Highway Traffic Safety Administration show that Florida leads the way as the deadliest state in the U.S. to ride a bike: The 133 cyclists killed in the Sunshine State in 2013 represented 5.5 percent of their total traffic fatalities.
But boring old walking is more dangerous than cycling, the numbers say:
Mile by mile, people in the UK are actually more likely to die walking than cycling, according to figures from the Department for Transport. For every billion miles cycled last year, 30.9 cyclists were killed, while 35.8 pedestrians were killed for every billion miles walked. Both activities are significantly safer than riding a motorbike – 122 motorcyclists are killed for every billion miles driven.
In the U.S., 5,376 of the 35,092 people killed in traffic crashes in 2015 were pedestrians, while 818 were on bikes. Both of those figures are at their highest levels since the mid-1990s. Collectively, bicyclists, walkers, and other motor-vehicle non-occupants represent 18 percent of the total toll, up from 13 percent in 2006.
Then there’s the fact that urban bike commuters are sucking down bonus amounts of air pollution from their exposure to trucks, buses, and theoccasional jackass in a pickup “rolling coal.” According to a 2011 study, London cyclists had 2.3 times more black carbon in their lungs, compared to pedestrians. Which sounds bad, but apparently isn’t:
As a cyclist, the stink of petrol fumes as you sit in traffic behind a lorry can be deeply off-putting, but it’s worth putting the issue in perspective. A recent study by Cambridge University found that the health benefits of cycling – as well as walking – outweigh the risks caused by air pollution in 99 per cent of cities.
There’s also a nifty graphic that aims to show exactly how long you can ride in your city before reaching that tipping point, depending on pollution level. But for Europe and North America, the risk is minimal. The worst city in the world for your lungs? Zabol, Iran. But it’s the dust, not the diesel, that’ll kill you there.
On the other side of the risk equation, as the FT authors conclude, is the very real danger of sitting on your ass all day, which contributes to far more early deaths in the industrialized world than overzealous bike commuting. “On a population level,” they write, “the dangers you face are offset by the many benefits associated with an active commute, which will translate for most people into increased life expectancy overall.”
James Hamblin recently made a similar observation over at The Atlantic, noting that the lethality of the modern sedentary lifestyle cannot be offset by occasional periods of intense exercise. What you need is a regular commitment to daily moving around. And that’s exactly what regular bike commuters get, even as they endure all the other miseries—and the occasional spasm of terror—that urban riding can sometimes deliver.