Who Knew Air Pollution Could Be So Much Fun?

Being a foreigner in China allows a certain amount of leeway to act a bit unusually in public and get away with it. One of my favorite eccentric activities has involved cruising around Beijing’s streets, suburbs and mountains to check out the air pollution levels. I’ve been personally interested (obsessed?) in air pollution since my arrival a year before the 2008 Olympics, and I have occasionally borrowed a handheld PM2.5 particle monitor from the obliging team at IQAir purifiers. My wife and I would drive around Beijing on weekend trips, me driving with one hand while the other hand is sticking my particle monitor’s tiny nozzle outside the window, sniffing the air like a dog’s nose. I would also bike around the streets of Beijing, stop occasionally and take out this large contraption from my bag, testing the air’s PM2.5 levels and taking notes. People walking by would always politely avoid eye contact. It didn’t help that usually I would be wearing a bike helmet as well as an air pollution mask, both very rare items on Beijing’s streets a couple years ago (helmets, sadly, are still very rare).

PM2.5 particle scanner air pollution chinaDuring these adventures, I recorded quite a few details about air pollution which truly surprised me — almost always in a bad way. One of my most disappointing findings was the mountain air around west Beijing’s dramatic hills and temples. I of course was expecting mountain air to be far cleaner than Beijing’s “yellow fog”. Isn’t the point of a mountain retreat to get away from it all? Unfortunately, my PM2.5 readings up there were just as disappointingly high as down in the city — mostly due to autumn leaf burning. I often monitor the AQI maps from the official website at zx.bjmemc.com.cn or the new map at www.aqicn.org which also includes the US Embassy’s station. Using these new maps, I’ve noticed countryside PM2.5 to be about the same as city air, except during windy or clear days where country air usually wins. No matter what time of year, we still like to “head for the hills” and joyride, especially on a hot summer day, but we don’t expect bluer skies out there.

I have also spent a lot of geeky time walking around Beijing’s shopping malls and streets recording PM2.5 data. One surprising finding was that I did not see an enormous difference in PM2.5 levels on the busiest roads when compared to the quieter side streets. I had always read that pollution peaks within 150 meters of busy roads, but I never noticed more than a 10% improvement from a ring road to a tree-lined canal road. I had been hoping that my rare jogging along the canals would offer a dramatic respite, but it wasn’t so. At least these tree-lined canal streets are still a much quieter and prettier experience. Plus, there still remains a lot of evidence of major illnesses such as heart disease in adults and childhood asthma in kids living within 75 meters of busy roads, so I think the general rule still applies: avoid major exercise, biking or walking along busy roads.

And if you must be on or along these major roads, definitely consider wearing an N95 certified pollution mask. Two recent studies based in Beijing had their test subjects walk along 2nd Ring Road and other busy streets, monitoring their breathing, heart rate and blood pressure. Imagine the looks they must have gotten, wearing a huge backpack with wires sticking out all over, and a mask covering their face! But the good news is, their encouraging findings showed a drop in blood pressure as well as heart rate variability when wearing the masks (a 3M N95 model). These two studies seem to be the strongest evidence so far that a properly fit N95 mask truly can protect you.

Another very disappointing finding during my testing was realizing that, on the really bad pollution days with AQI over 300, most stores and restaurants had indoor air levels almost as dangerous as the outdoor air. In general, I found indoor air levels to be around 50-80% of outdoor readings. But that means on an all-too-typical AQI spike over 300, the indoor air will still be quite unhealthy. I was most astonished to walk into Beijing’s most famous expat bookstore, to find their indoor air to be even worse than outside! So much for a literary escape. The main reason here was their indoor cigarette smoke, and this confirmed the obvious: non-smoking sections are completely ineffective without proper ventilation. Fortunately since then, they have permanently forbidden indoor smoking. This is no small act of corporate courage in China, and I desperately hope other companies follow their lead.

On that very same wicked day of “very hazardous” air with an AQI over 400, I found zero stores and buildings with PM2.5 levels safely in the green zone. It was especially disastrous within every store in Sanlitun’s popular Village mall. All of those large open doors and open-air walkways spelled doom and gloom for my lungs — as well as the health of their employees.

The one silver lining on this day was where it counted the most — in my own home, and specifically in the bedroom. Since most adults spend 90% of our lives indoors, and one third of our lives are in our bedrooms asleep, it’s a no-brainer for me to protect my family with decent air purifiers in the bedrooms. Turn it on, close the door and go to sleep. Voila! One third of your lifetime in China is essentially free of pollution. I’m not just being poetically dramatic here; I personally have done rigorous workouts of multiple brands of air purifiers in my apartments. With the bedroom doors closed, all three machines reduced PM2.5 air pollution levels 95-99% less than the outside air. And this was at their quieter settings, which is not so easy for many machines. I’ve gotten used to their quiet hums as a relaxing and protecting white noise.

So there you have it, one man’s obsessive odyssey around Beijing. While much of my data was very concerning, I still find having this hard data reassuring on a certain level. At least I now know exactly how bad things can be — as well as how much I can improve it.


This is my latest article to be translated into Chinese and printed in the New York Times China edition where I have a regular health column called 北京健康札记. You can read my previous New York Times articles here in English and in Chinese.


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