Pollution warning for cyclists

Does air pollution mean cycling in London is now bad for your health?

I spend an hour and a half a day cycling to and from work. Whilst sat on my saddle inhaling exhaust fumes I often wonder whether I’m doing myself more harm than good.

To find out, I enlisted the help of Dr Ben Barratt from Kings College London. He fitted the two of us with air pollution monitors which measure the number of the smallest particles most commonly produced by vehicles. We then cycled 8 miles to central London to see how much pollution we were exposed to.

I took my usual route crawling along Brixton Hill, through Elephant and Castle and over Blackfriars Bridge. The readings showed I exceeded the World Health Organisation's safe limit of 25ugm3 numerous times. (25ugm3 is the first level shown on the map below, above which the red line -Ben's - peaks just once, but mine does repeatedly)

Martin's levels (in blue) show peaks as he cycles behind heavy traffic Credit: King's College London

Dr Barratt took a back route winding along side roads and keeping away from traffic. He cycled further but as there was less traffic he arrived at the same time. His readings are dramatically different. In total he was exposed to a third of the amount of harmful particles that I was. He plotted his route using an App available on this website

Martin experienced 3 times higher exposure on main roads Credit: King's College London

There are proven medical links between exposure to certain types of air pollution and heart attacks, strokes and lung conditions. So should I stop cycling all together?

No is the simple answer according to Dr Rossa Brugha from Queen Mary University. He says research carried out by a Spanish university proves the health benefits of cycling are eighty times greater than the risks from air pollution.

Stills in this video provided by 'London cyclist' blog.

Part of the reason is that there is no pollution free alternative. Walking and taking the train have lower levels of exposure but less benefit from exercise. Sitting in a bus or car has the same exposure as cycling whilst some areas of the underground are up to three times higher.

Exhaust-related pollution very similar to fine dust, demonstrating that most of the fine dust was from vehicles Credit: King's College London

The chart above shows exhaust-related pollution is very similar to the fine dust level, demonstrating that most of the fine dust on this day was from vehicles. While the highest peak is near the start in outer London, average levels rose as I travelled towards central London