Forget Biking in Bad Air – Worry About Protecting Yourself While Working Out or Clubbing in Beijing

Many Beijing pollution fighters have already read the article that ran in the The Guardian this week referencing a 2016 report on the effects of excercise in polluted cities the one that said the benefits of cycling are rendered moot after 105 minutes huffing and puffing in Beijing's smoggy air.

The post, part of that British media outlet's excellent week-long series on air pollution, is another grim reminder of the long way we have to go before we can truly call ourselves safe from the dangers of air pollution.

However, let's take a closer look at that figure of the 105-minute "tipping point" for Beijing.

The article bases its premise on the average annual particulate matter concentration in Beijing (85 micrograms per cubic meter as of last year), and a certain level of aerobic activity one undertakes by biking (6.8 METs, a measure of physical effort).

Using these data points, the original report calculates that by the 105th minute, the damage from the amount of pollution one breathes outweighs the exercise benefits you'd get from from biking.

But let's not forget that it's not a nice, even 85 micrograms out there all the time that's an overall average. At time of this blog going online, the PM2.5 concentration is 226, more than 2.5 times higher than 85, which brings the biking tipping point down to under 30 minutes.

However, this calculation presumes that you are not wearing a mask. Donning even a cheap disposable surgical mask  which tests have shown can reduce particulate matter intake by 80 percent (other masks can filter out as much as 99 percent) – would signficantly cut that exposure. An 80 percent reduction in 85 micrograms per cubic meter brings that down to 17, a low enough point that you would effectively never reach the so-called tipping point.

While mask wearing is by no means ubiquitous amongst bikers in Beijing, it's certainly more common to strap one on while cycling than it is for other heavy breathing activities  such as working out at the gym, dancing in a nightclub, or having sex  where mask use is a lot less common (unless you'e into the kinky stuff).

So using the biking data as well as a chart of METs for various activities, and presuming you are not wearing a mask during those activities, here's your tipping points:

Dancing (7 METs): 102 minutes
Using a stairmaster (9 METs): 79 minutes
Step aerobics (10 METs): 71 minutes
Running, 10 min mile (10 METs): 71 minutes
Freestyle swimming (10 METs): 71 minutes
Running, 5.5 min mile (18 METs): 40 minutes

As for vigorous sexual activity, one source says its MET equivalent is 1.5, which means you could make passionate love for seven hours and 56 minutes before reaching the tipping point (go for it, Romeo). A second source puts sex's MET equivalent at 5.8, which means two hours and three minutes before you reach your point of more harm than good (a point you've probably reached already, psychologically speaking).

The dancing bit has us pretty freaked out. After all, have you seen the air in a typical nightclub, even one that does not allow smoking? We haven't seen many mask-wearing clubbers this side of Halloween, and the air on the dancefloor is often considerably worse than outside due to cigarettes, smoke machines, poor filtration, and lots of jostling bodies.

And while you may not imagine yourself dancing (or even biking) non-stop for two hours every day, it's easy to imagine a non-masked night out in Beijing adding up to well beyond the tipping point; biking around Gulou, cutting a rug in front of a live band in a smoker-friendly venue, feasting on a few sizzling lamb kebabs, then biking home to make sweet, sweet unfiltered love in dingy hutong apartment.

How about working out in an unfiltered gym? Our recommendations to you: wear a mask during your workout unless you know your gym is filtering the air and can prove it with an on-site air monitor.

Having said all this, some of our city's leading pollution watchers do say to take these studies with a grain of salt. Jeff Bauer, co-founder of the AQblue Mask company says that he is skeptical of these types of studies because putting a specific time of pollution exposure in minutes per day seems inaccurate when there are still so many unknowns regarding pollution’s long term health effects.

“The article doesn’t mention that pollution found near roads is a little different to the pollution around the city, not to mention how sensitive groups like young children and elderly are affected differently than a healthy 20-30 year old.”

“Personally I think it’s important not to worry so much about the specific ‘tipping point times’ but to be sensible about your health,” Bauer says. “When the pollution is bad, I don’t go running outside. I wear a mask to get from point A to point B.”

Regardless of any flaws that may be in the study's findings, it at least has us thinking about when to be active or rest easy, along with refreshing our memories about Beijing venues that utilize air purifiers (which you can read more about here). Now all we need to do is find a mask that doesn't clash with our clubbing attire.

More stories by this author here.
Twitter: @MulKyle
WeChat: 13263495040

Photos: ARTeUTILe, Getty Images, Hindustan Times


Got some interesting feedback from a reader who is also an avid cyclist. He says the Guardian article is "perhaps making this issue sound worse than it is." He says "the key point being that the research group doubled the background pollution levels to work out the tipping points," before citing this paragraph from the Preventitive Medicine Journal study that is the basis for the article:

"This study indicates that, practically, air pollution risks will not ne- gate the health benefits of active travel in urban areas in the vast major- ity of settings worldwide. Even in areas with high background PM2.5 concentrations, such as 100 μg/m3, up to 1 h 15 min of cycling and 10 h 30 min of walking per day will lead to net reduction in all-cause mortality (Fig. S5, supplementary material). This result is supported by epidemiological studies that have found the statistically significant protective effects of PA even in high air pollution environments (Matthews et al., 2007; Andersen et al., 2015). However, a small minor- ity engaging in unusually high levels of active travel (i.e. bike messen- gers) in extremely polluted environments may be exposed to air pollution such that it negates the benefits of PA."

Keep in mind that the tests showing surgical masks as 80% effective were done by shooting particulate matter directly through the filter. Wearing surgical masks leave the sides vulnerable to pollution coming through the gaps between your face and the mask. From a "fit test" performed on a surgical mask, we see about 60% effectiveness. In reality, while wearing a mask, it's extremely important to make sure it fits/seals the face properly.

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