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Cycle under 12mph in cities to reduce pollution inhalation

Study finds sweet spot for fastest travel with least pollutant damage

Cycling at between 12 and 20 kilometres per hour (7.5- 12.5 mph) in cities will minimise your inhalation of air pollution, a new study has found.

Pedestrians should limit their speed to two to six kilometres per hour (1.2 - 3.7 mph) too, to gain the health benefits of exercise without dangerous particle inhalation.

Writing in the International Journal of Sustainable Transportation, Alex Bigazzi, a University of British Columbia transportation expert, calculated minimum-dose speeds (MDS) for different age and sex groups.

Female cyclists under 20, were found to have an ideal speed linked to the least pollution risk of 12.5 kilometres per hour on average on a flat road.

For male cyclists in the same age group, it's 13.3 kilometres per hour.

Ideal travel speeds were at 13 and 15 kilometres per hour for female and male cyclists in the 20-60 age group.

"If you move at much faster speeds than the MDS—say, cycling around 10 kilometres faster than the optimal range—your inhalation of air pollution is significantly higher," Bigazzi told Medical Xpress. "The good news is, the MDS numbers align pretty closely with how fast most people actually travel.

"The faster you move, the harder you breathe and the more pollution you could potentially inhale, but you also are exposed to traffic for a shorter period of time. This analysis shows where the sweet spot is.”

Last year we reported how all 50 of Britain’s worst air pollution blackspots are in London. Each has at least double the EU limit for nitrogen dioxide (NO2), which is generated by emissions from diesel vehicles and linked to asthma and other respiratory problems.

According to data obtained under Freedom of Information, the most polluted street is Marylebone Road, followed by Park Lane, Knightsbridge, the Hammersmith Flyover and the East Ham and Barking Bypass.

While the European Union sets a limit of 40 micrograms of NO2 per cubic metre on average per year, the junction between Marylebone Road and Glentworth Street showed 132 micrograms and all 50 pollution blackspots exceeded 80 micrograms.

Last year, Oxford Street was found to have a peak level of nitrogen dioxide of 463 micrograms and an average of 135. David Carslaw, an emissions researcher at King’s College London, remarked that this was to his knowledge the highest in the world in terms of both hourly and annual mean.

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