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Study shows that urban cyclists have higher levels of black carbon in lungs than pedestrians

Cyclists in London and other major cities have higher levels of black carbon in their airway cells, according to research presented at the European Respiratory Society’s Annual Congress in Amsterdam. The results suggests that cyclists inhale more black carbon than pedestrians, which may cause damage to the lungs.

The combustion of fossil fuels results in the generation of large numbers of inhalable particles of soot (black carbon). There is increasing evidence that inhalation of black carbon particles is associated with a wide range of health effects, including heart attacks and reduced lung function.

The researchers, led by Professor Jonathan Grigg from Barts and the London School of Medicine, aimed to identify whether the way healthy adults commute to work affects their exposure to black carbon. Specifically, they tested the hypothesis that cyclists have higher personal exposure to black carbon.

To test this theory the study compared the lung dose of black carbon in cyclists and pedestrians. To measure lung dose the researchers sampled a lower airway cell called the airway macrophage—a specialized cell that sits on the airway surface and ingests foreign material.

The researchers collected sputum samples from five adults who regularly cycled to work in London and five pedestrians and analysed the amount of black carbon found in their airway macrophages. All participants in the study were non-smoking healthy urban commuters aged between 18 and 40 yrs.

The results showed that in this small sample, cyclists have 2.3-times more black carbon in their lungs when compared with pedestrians. The probability that this difference occurred by chance is less than 1 in 100.

The results of this study have shown that cycling in a large European city increases exposure to black carbon. This could be due to a number of factors including the fact that cyclists breathe more deeply and at a quicker rate than pedestrians while in closer proximity to exhaust fumes, which could increase the number of airborne particles penetrating the lungs. Our data strongly suggest that personal exposure to black carbon should be considered when planning cycling routes. Whether cycling by healthy individuals is in itself associated with adverse health effects is currently being assessed in a larger ongoing study.

—Dr Chinedu Nwokoro, one of the researchers of the study



Another benefit of electric cars.

Thomas Lankester

So there are 2 mechanisms put forward to explain the results:
1) proximity to vehicle exhausts;
2) depth of inhalation.

So why did they not compare cyclists to motorists? Being relatively sedentary, motorists should have lower depth of inhalation but they sit right in the traffic stream, with their air intakes even closer to other vehicle exhausts than cyclists are.


This is either misleading research, or a misleading interpretation of the results. It's tantamount to saying that people who exercise have a 200% greater chance of breaking their leg. Hence, don't exercise?

Is there sound evidence to demonstrate that taken as a *whole*, being an urban cyclist is worse for your longevity than sitting in a car breathing the same fumes (or more)? All studies like this make me want to do is eliminate automobiles altogether from urban cores because they're clearly a public health hazard to cyclists, pedestrians, and the poor folks living near the exhaust.

I understand this is a "green car" forum, but even in the most optimistic scenario, we won't see a critical mass of electrics on the road for a decade or more.


..but it's not just cars is it? Its buses and other larger vehicles. I know of many streets restricted to buses in cities that just reek of soot and particulates. So it's not just a car issue.

Another paradox in transport planning is also the nonesence of deliberately restricting vehicular movement with reduced roadspace - often with acres of hatched tarmac rather than something useful like a wider pavement or planted verge, excessive traffic lights and other new realist designer congestion measures which reduced the overall capacity for movement in cities and drive up, shock-horror, emissions!

French Engineer


buses can come with GTL, special particle Filters, Hybrid, electric, in more and better way than private cars.
That's the case where I live (Europe). Buses only reeks from sooth when you from times to times still meet an old bus taken of retirement for some reason (tramway repair, work on the suburban train tracks...). You immediately notice how bad it was before.

With the emerging health data about sooth particles, I am ready to bet it is demonstrable that the investment in clean buses would be very quickly returned.
You just need to agree to invest more in mass transit day to day budget.

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