Never exercise at rush hour: six ways to avoid air pollution

Last month, air pollution was named as the biggest risk to public health in Europe. It is responsible for the early deaths of an estimated 400,000 Europeans each year, 40,000 of whom are in the UK. Moreover, the UK, among other countries, regularly breaches EU pollution limits – which are lower than the World Health Organization standards. London reached its legal limit for 2018 in just one month, and a report by the WHO in May found 30 British towns and cities, including Manchester, Swansea, Leicester and York, that exceeded WHO limits.

Air pollution has been linked not only to lung disease, but cardiovascular disease, stroke and dementia. Besides that, it has been linked to lower cognitive function, and a rise in mental illness and asthma in children. While it is already known that air pollution can increase the risk of premature birth, it was recently reported that scientists have discovered particles of pollution in mothers’ placentas, and that the pollution may have reached foetuses. And, last month, a study found that children in the UK were absorbing a disproportionate amount of toxic black carbon particles from diesel engines on the way to and from school, and even in classrooms and playgrounds. The main solution, of course, is to drastically reduce pollution, but in the meantime, what can we do to protect ourselves?

Avoid polluted streets

“If you have a choice, you can reduce your exposure by using quieter streets,” says Audrey de Nazelle, lecturer in air pollution management at Imperial College’s Centre for Environmental Policy. One study last year by King’s College London showed that taking a side street could reduce average exposure to air pollution by 53%, and in some cases up to 60%.

“You get an exponential reduction,” says Prashant Kumar, director of the Global Centre for Clean Air Research at the University of Surrey. Within the first few metres of the roadside, “the concentrations are really high and then they dilute quite quickly. Within 50 or 100 metres, depending on the pollutant types, they reduce to at least half of their concentrations.”

Streets with tall buildings on each side, known as urban canyons, can be more polluted, as pollutants become trapped. Don’t assume that trees automatically signify a cleaner space: tall trees, with their canopies close together, can also decrease the dispersal of pollution, especially if they are in the vicinity of tall buildings. What planners should be doing instead, says Kumar, is planting lower level hedges, which act as a barrier between the polluting road and pedestrians.

Use apps

Air pollution apps, says Stephen Holgate, a professor of immunopharmacology at the University of Southampton and an air pollution expert, are “quite good and they’re improving. There are apps where a city or town has a real-time update of what the air pollution is, so you can make choices about where to avoid ... they’re really helpful.” London Air was developed by King’s College London and shows levels of pollution at sites across the city. Holgate also points to the growing market in personal sensors, which – when paired with a phone – can monitor levels of pollutants such as nitrogen dioxide and particulate matter. However, scientists, and bodies such as the Department for Environment, Food and Rural Affairs and the US Environmental Protection Agency, have warned they are still in their infancy and their measurements may not be reliable.

Avoid rush hour exercise

In the UK, even with our sometimes illegally high air pollution, the benefits of exercise seem to outweigh the risks of pollution exposure, says De Nazelle. “Theoretically, it makes sense that physical activity would protect you from the harms of air pollution,” she says. “There are many benefits to exercise, but one is reducing inflammation and one of the major mechanisms of air pollution on health is to increase inflammation in the body. By doing physical activity, you’re combating the negative effects of air pollution. It’s hard to prove at this point but there is some indication that that’s the case.”

As for days when pollution is high, De Nazelle says: “It’s hard to say if it really makes sense to go running along high traffic roads, we don’t really know. If you’re very young or very old, or you have a heart or respiratory condition then you are probably better off not being physically active outdoors on days of high-level air pollution.”

Is there a best time of day to exercise? “Avoid rush hour, basically,” says De Nazelle. “And right before the rush hour is probably better than right afterwards.” Early in the morning may be better, says Kumar. During the morning rush hour, he found that levels of PM2.5 – particulate matter of 2.5 microns or less, which can penetrate the lungs and enter the bloodstream – were higher than in the afternoon rush hour.

Leave your mask at home

“The majority of masks leak, they get clogged up and they don’t really work,” says Holgate. In order to be effective, they would have to be very tight-fitting and would be “so uncomfortable to wear that most people wouldn’t be able to tolerate them”. A study by researchers from Edinburgh’s Institute of Occupational Medicine and others, which looked at nine masks available to consumers in Beijing, where air pollution is high, found that average leakage was between 3% and 68% in sedentary tasks and 7% to 66% during activity.

Eat a healthy diet

There is growing evidence that what we eat may mitigate the harmful effects of air pollution. A study, presented this year by researchers at New York University’s School of Medicine, examined data from more than 500,000 people, looking at their adherence to a Mediterranean-style diet and their estimated long-term exposure to air pollution. The results suggested that, when taking into account exposure to pollution, those who most closely followed the diet were less likely to suffer cardiovascular disease, and deaths from all causes were lower. “These pollutants increase oxidation in the body and if you have antioxidants – things like vitamin C, and the other vitamins found in fruit and vegetables – on board they can help neutralise it,” says Holgate. “The problem is a lot of people in this country [don’t get enough] in their diet and often it’s the people who live in the poorest places as well and get the most exposure, so there is an interaction there.”

Cover your baby’s pram or pushchair

A study published this year showed babies and young children could be exposed to 60% more air pollution than adults. One of the problems, says Kumar, whose department carried out the study, was that the height of children – whether walking or in a pushchair or pram – was below one metre and therefore nearest the exhaust pipes of vehicles. “In this first metre above the ground, you get the highest concentration of the fumes,” he says. “The concentration usually decreases as you go up.” And, he adds, a child’s immune system is not developed and they are not as well protected as adults.

The researchers are currently running experiments on whether different types of pram or pushchair are better (forward-facing or backward-facing, for instance), but in the meantime, Kumar advises staying away from busy roads where possible and using a cover, which will reduce some but not all pollution, particularly at hotspots such as traffic lights, bus stops and junctions. A plastic raincover will do, although he points out it won’t be snug (so pollution will leak in) and it could be uncomfortable for the child in hot weather. Products such as a baby pillow that filters the air around a child’s breathing area are about to come on to the market. “The permanent solution,” says Kumar, “is to tackle the source – the vehicles.”