Airy menace: The hidden benefit of exercising in a mask

Wearing a mask while exercising on busy roads has another benefit besides helping protect against covid. By Nicky Pellegrino

Since the pandemic began, it has become more common to see people wearing masks while
exercise in crowded urban areas. In addition to protection from Covid-19, runners, pedestrians, and cyclists get another benefit: A well-fitting N95-style mask will filter at least some of the pollution out of the air.

Breathing ultrafine pollution particles is bad for our health. The haze of pollution does not only enter our lungs; there is evidence that it passes into the bloodstream, potentially affecting every organ and cell in the body.

There are tens of thousands of scientific studies showing the harm of inhaling toxic air. In addition to respiratory diseases, it has been linked to several types of cancer and an increased risk of heart attack and stroke. Air pollution particles have been found lodged in the placenta of pregnant women and have been associated with low birth weight in babies.
The more you breathe, the more air pollutants you attract. Now there’s new research showing that if people exercise vigorously in poor-quality air, the expected brain improvements from physical activity all but disappear.

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 lower risk of dementia, with healthier gray and white matter, unless athletes were exposed to even moderate levels of air pollution.

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

The World Health Organization (WHO) states that a whopping 99 percent of the world’s population breathes air with levels of pollutants that exceed their reference limits and has estimated that this kills about seven million people each year.

In New Zealand, our long, narrow landmass and often windy weather work in our favor. Furthermore, as an isolated island nation, we are rarely affected by pollution from our neighbors. However, poor-quality air continues to cause premature deaths and hospitalizations.

“What I generally say about New Zealand’s air quality is that it’s absolutely brilliant most of the time in most places, but there are a few key exceptions,” says Dr. Ian Longley, air quality scientist at Niwa.

One such exception is when you’re on the side of a busy highway. “Our vehicles are by no means the cleanest in the world, and the morning rush hour is particularly bad because there isn’t much wind to blow away the pollution,” Longley explains.

The continued use of solid fuels such as wood and coal for heating is contributing to the problem.

“So, really, we have extremes in air quality, depending on where you are, the time of day, and the time of year,” says Longley. “In areas of the South Island, air quality can be as bad as in Chinese cities on some winter nights.”

Longley monitored air quality in Auckland, Wellington and Christchurch for seven weeks during the first lockdown and found that it changed dramatically. He estimates that pollution was reduced by three quarters on average and many Aucklanders reduced their exposure to traffic pollution by 90 per cent during the lockdown.

“In a sense, this has proven something I’ve been saying all along. Almost all air pollution is potentially under our control,” he says.

The transition away from solid and fossil fuels will take time. In the meantime, Longley says, all the evidence shows that exercising outweighs the risks posed by air pollution.

“Still, you don’t want to breathe pollution if you don’t have to. Research I was involved in looked at bike lanes. We found that a cyclist doesn’t need to be too far away from traffic to get a big benefit. Five meters and 10 meters actually make a big difference, 20 meters even more, in reducing the amount of pollution you breathe.”

If you can’t avoid riding your bike through city traffic, then it’s worth putting on a mask.

“It won’t filter everything, but it will certainly lower the dose to the body,” says Longley. In a way, mask wearing is the ambulance at the bottom of the cliff, she adds. “It’s not solving the problem, but it does highlight that there is a problem that needs a solution.”