Some of us may have seen (or are ourselves) people wearing face masks when moving through the city. In 2012, US athletes arrived in Beijing for the Olympic Games wearing face-fitted air filtration masks (termed respirators) to avoid an expected short-term drop in exercise performance (through inflammation affecting the capacity of the airways and lungs) caused by exposure to very high levels of air pollution such as that which troubles cities like Beijing.
The benefits of exercise from activity such as bicycle commuting outweigh the higher potential exposure to air pollution
As environmental health researchers, we at CREAL (an ISGlobal allied centre) are often asked whether exercising in a polluted area poses a risk for health. Generally, we say that the benefits of exercise from activity such as bicycle commuting outweigh the higher potential exposure to air pollution such as emissions from nearby traffic. Over the long-term, incorporating regular exercise into a daily routine such as bicycle commuting is advisable not just for personal health benefits (which also generally outweigh other risks such as collisions) but also to benefit everyone else in the city since it may mean one less car emitting air pollution and noise, posing a traffic accident risk or causing congestion.
While this advice is general, sensitive populations (such as asthmatics) may maximise the personal benefit of exercising by considering risk management strategies, including avoiding traffic where possible or wearing respirators. These strategies should only be seen as a short-term answer to a large, longer-term problem: too much air pollution in cities carries a certain risk to us all, no matter our mode of transport, profession or social activities. We need cities overall to become cleaner places to breathe and through this live longer and more productively, as elevated air pollution levels are known to reduce life longevity and development in children. While the emission sources remain, one strategy for reducing exposure to elevated levels is to avoid the source, such as by taking backstreets to avoid traffic congestion when commuting or exercising. Another strategy is to use a respirator similar to that used by US athletes in Beijing.
Sensitive populations (such as asthmatics) may maximise the personal benefit of exercising by considering risk management strategies, including avoiding traffic where possible or wearing respirators
Respirators are available for different occupations, allowing protection from different pollutants and at different comfort levels (e.g. breathing rates). For example, a professional carpenter may use an industrial-grade dust respirator that excels at stopping wood-sand from being inhaled. There are several respirators marketed as appropriate for ‘active’ city living, including specifically for bicycle commuting. These products claim to be comfortable for physically-active commuters as they are made of neoprene (similar to suits for watersports) and house two filter inlets rather than one, accommodating sweat and a higher breathing rate, respectively, expected with exercising. They are not, however, entirely tested and shown to be effective for the broad range of traffic emissions that we may be exposed to at elevated levels in cities. They typically only filter the big particles and some gases, and not the smaller (ultrafine) particles and certain gases that are known to be particularly damaging to our health, such as nitrogen dioxide and sulphur monoxide.
A scientific study in Beijing looked-at how well a range of face masks could stop fresh diesel exhaust particles being inhaled. They found that while respirators marketed for bicyclists were a lot more effective than a cotton handkerchief, they were a lot less effective than the type of respirators that may be used by carpenters. A more recent study showed that patients with a heart condition experienced less symptoms when wearing the industrial-grade respirator, while the bicyclist respirators were not selected for health-effect testing due to their significantly lower performance and thus protective effect. Patients with conditions affecting the heart and lungs may be particularly sensitive to high levels of air pollution, and in their case may be recommended strategies to reduce their exposure and symptom exacerbation. Those affected by respiratory infections should also try to reduce their exposure as much as possible.
We need cities overall to become cleaner places to breathe
Regardless of whether the filter is effective or not, one issue with relying on a respirator is that they need to fit and be worn properly, ensuring that all air (and pollution) inhaled goes through its filter/s. While the onus should be on relevant city authorities and government officials to improve air quality, ultimately, it is a personal decision to wear something such as a respirator. This decision may come down to cultural and practical factors. The Beijing study found that (industrial) respirators were well-tolerated, but this was used when walking rather than more vigorous exercise like bicycling.
My previous colleagues at the International Laboratory for Air Quality and Health (Brisbane, Australia) and I wanted to know if bicyclists were willing to do something such as wearing a respirator and why. Brisbane, like Barcelona, is blessed with a sunny, temperate climate conducive to bicycling; unfortunately, traffic and their emissions are there also dictating conditions for city-dwellers. In our scientific study we saw some short-term health complaints but mostly in people with a history of respiratory disorder (e.g. asthma). The majority of participants showed a willingness to avoid traffic or wear a respirator if shown to be necessary for health. Even though re-routing to avoid traffic is seen to significantly reduce exposure to traffic-related air pollution, participants were more willing to use a respirator (if comfortable). For bicycling routes to be desirable, it was suggested that they need to be separated from other traffic on main roads for quicker, safer commutes.
While respirators marketed for bicyclists are a lot more effective than a cotton handkerchief, they are a lot less effective than the type of respirators that may be used by carpenters
In the bigger picture of public health, my colleagues from CREAL have stated that the standard level of emissions from traffic, a hot topic now that a major vehicle manufacturer has been exposed as cheating their standards testing, is irrelevant – they argue that cars in general should be replaced by active mobility modes, since noise and physical activity need to be considered with health risks and benefits, respectively. Until our city authorities deal with this challenge, some services do exist for people to see when and where air quality may be particularly bad, such as during peak hour traffic at major road intersections. This type of service can be tailored for route planning, allowing the user to identify a way to school or work that is of better air quality. The European Commision-backed project CITI-SENSE is developing systems for a service like this, creating real-time updated maps of air quality in several European cities. If you are thinking about the level of air pollution around you, let us know your thoughts where you are – download the CityAir app, available for both Android and iOS. Your input is confidential yet will go towards enlightening city leaders and authorities on public opinion of air quality. Meanwhile, reconsider wearing a respirator and instead a big smile – show the city how happy you are to be bicycling and a harbinger of health benefits.
[This text was originally published in Spanish in El País - Planeta Futuro]