London, Sep 28 (IANS): Commuting to work by walking on quieter side streets rather than main roads can help people avoid exposure to harmful air pollution, says a new study.

Lee Koh from London's Queen Mary University used a hand-held monitor to measure levels of black carbon particulate matter while walking between Whitechapel in the east of London to Moorgate, between 4.00 p.m. to 7.00 p.m. using main roads.

She then used an urban walking route planner to plan a quieter route that might potentially have lower levels of air pollution.

Short-term exposure to black carbon is associated with increased hospital admissions due to respiratory symptoms, and that long-term exposure is associated with exacerbations and increased prevalence of asthma.

Black carbon is one of the components of air pollution, and comes from incomplete combustion by diesel vehicles.

"We found in this small study that people could avoid peaks in black carbon if they choose to walk a quieter route," Koh said.

Walking the busy and quieter routes six times, Koh found that there was a statistically significant difference in the peaks of exposure to black carbon between the two routes.

"The peaks are when much higher levels of pollution are present. For example, when you stop to cross a busy road and so you are subject to a higher level of pollution compared to when walking away from the traffic," she explained.

There were no peaks in black carbon exposure on the side-street route, while on the busy route there were three occasions when the levels of black carbon exceeded 10,000 ng/m3 for every five minutes.

The findings were presented at the European Respiratory Society's International Congress, 2015.