Cyclists in big cities inhale more soot

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AMSTERDAM, Netherlands, Sept. 25 (UPI) -- People who cycle through big cities inhale more black carbon than pedestrians, which may cause lung damage or trigger heart attacks, British researchers say.

Study leader Jonathan Grigg from Barts and the London School of Medicine and colleagues 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 said.

The researchers collected sputum samples from five adults -- all non-smoking healthy urban commuters age 18-40 -- who regularly cycled to work in London and five pedestrians and analyzed the amount of black carbon found in their airway macrophages.

The study found cyclists has 2.3-times more black carbon in their lungs compared with pedestrians. The probability that this difference occurred by chance is less than 1 in 100, the researchers said.

"The results of the study have shown that cycling in a large European city increases exposure to black carbon," Dr. Chinedu Nwokoro, one of the researchers of the study, said. "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."

The findings were presented at the European Respiratory Society's annual Congress in Amsterdam.