Airy menace

Wearing a mask while out exercising on busy roads has another benefit besides helping protect against Covid.

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Since the pandemic began, it has become more common to see people wearing masks while out exercising in busy urban areas. As well as protection from Covid-19, those joggers, walkers and cyclists are getting another benefit: a well-fitting N95-style mask will filter out at least some air pollution.

Breathing in ultra-fine particles of pollution is bad for our health. The haze of pollution doesn't enter only our lungs; there is evidence that it passes into the bloodstream, potentially affecting every organ and cell in the body.

If people exercise vigorously in poor air, the expected brain improvements almost disappear.

There are tens of thousands of scientific studies that demonstrate the harms of inhaling toxic air. As well as respiratory illness, it has been linked to a number of cancers and an increased risk of heart attack and stroke. Particles of air pollution have been found lodged in pregnant women's placentas and it has been associated with low birth weight in babies.

The more heavily you breathe, the more air pollutants you draw in. Now there is new research to show that if people exercise vigorously in poor-quality air, the expected brain improvements from the physical activity almost disappear.

Testing the air: Dr lan Longley.

Researchers from the universities of Arizona and Southern California, using data from the UK Biobank, found that vigorous exercise was linked to better brain health and a reduced risk of dementia, with healthier grey and white matter, unless exercisers were exposed to even moderate levels of air pollution.

In another recent study, researchers from Fudan University in China found that men living in areas of high air pollution have decreased sperm motility.