Can pollution cut the health benefits of cycling to work?

Cyclists in London have said they feel claims that commuting to work by bike can halve the risk f developing cancer and heart disease have been overstated.

As we reported earlier this week, the University of Glasgow study found that compared to people who commuted by car or on public transport, regular commuter cyclists were 41 per cent less likely to die from any cause.

But riders in the capital were quick to point out that their journeys did not feel healthy.

Cycling to work can cut cancer and heart disease, says study (unless the air pollution from London buses gets you). https://t.co/uWMqC9ZbMY

— Ben Waterton (@bwaterton) April 20, 2017

Cycling to work can cut cancer&heart disease - would be gd 2 know impact of pollution in this, especially in London https://t.co/ABmw1pPZ9F

— Flo Mowlem (@FloMowlem) April 20, 2017

But Donnachadh McCarthy, co-founder of campaign group Stop Killing Cyclists, told the Standard he "welcomed the study".

"The pollution is not any worse for cyclists than motorists so it's still hugely beneficial to cycle," he said. "For people over the age of 65 it adds three years to their life.”

We’ve also reported on how a recent study concluded that the benefits of physical activity almost always outweigh the negative effects of pollution for those cycling in urban areas. Researchers say their findings should encourage people out of their cars and onto their bikes and in so doing reduce pollution levels further.

London’s air pollution, which is caused primarily by traffic and diesel fumes, is responsible for 9,500 premature deaths each year, according to a 2015 study by King’s College, London. Thanks to their proximity to traffic and deeper breathing, a cyclist can expect greater exposure to that threat than most.

According to a 2011 study by researchers from the London School of Medicine, a cycle commuter inhales more than twice the amount of black carbon particles as a pedestrian making a comparable trip. Stopped on your bike at a set of traffic lights, wallowing in the fumes, these kinds of things have probably crossed your mind.

But a recent Cambridge University study found that the health benefits of cycling outweigh the risks caused by air pollution in 99 per cent of cities. Is the capital one of them? How long would you have to cycle in London before the effects of pollution started to outweigh the benefits of cycling?

The researchers established tipping points for each of the cities they looked at – the length of time after which the impact of pollution started to outweigh the positives that come with being more active.

Dr Marko Tainio from the MRC Epidemiology Unit at the University of Cambridge, who led the study, said: “Our model indicates that in London health benefits of active travel always outweigh the risk from pollution.”