Tipping point: revealing the cities where exercise does more harm than goodIn at least 15 cities, air pollution has now become so bad that the danger to health of just 30 minutes of cycling each way outweighs the benefits of exercise altogether, according to new research
In cities such as Allahabad in India, or Zabol in Iran, the long-term damage from inhaling fine particulates could outweigh the usual health gains of cycling after just 30 minutes. In Riyadh, Saudi Arabia, this tipping point happens after just 45 minutes a day cycling along busy roads. In Delhi or the Chinese city of Xingtai, meanwhile, residents pass what the researchers call the “breakeven point” after an hour. Other exercise with the same intensity as cycling – such as slow jogging – would have the same effect.
“If you are beyond the breakeven point, you may be doing yourself more harm than good,” said Audrey de Nazelle, a lecturer in air pollution management at Imperial College’s Centre for Environmental Policy, and one of the authors of the report.
The study, originally published in the journal Preventive Medicine before the World Health Organization’s latest global estimates, modelled the health effects of active travel and of air pollution. They measured air quality through average annual levels of PM2.5s, the tiny pollutant particles that can embed themselves deep in the lungs. This type of air pollution can occur naturally – from dust storms or forest fires, for example – but is mainly created by motor vehicles and manufacturing.
Countries include: China, India, Qatar, Bangladesh, Kuwait, Iraq, Pakistan, Nigeria, Saudi Arabia, Iran, Uganda.
Breathing polluted air has been linked to infections including pneumonia, ischemic heart disease, stroke and some cancers. The Institute for Health Metrics and Evaluation’s Global Burden of Disease study ranks it among the top risk factors for loss of health.
Full article and list of cities: https://www.theguardian.com/cities/2017/feb/13/tipping-point-cities-exercise-more-harm-than-good
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