I’ve been writing quite a few posts on air pollution lately, and I decided to get some hands-on data which I’d like to share with everyone. The good folks at IQAir allowed me to borrow one of their handheld particle scanners (see picture below); I then got a week of sample data from a variety of places, both indoors and outdoors, urban and rural. I must admit that many conclusions were surprising!

The Most Surprising Findings

OK, first some dull technical jargon: the particle machine uses a laser to measure fine dust particles in the air down to PM0.3 microns, which is much smaller than the measured PM10 or PM2.5 but a good reference point. (The conversion chart is at the bottom of this post). One basic to remember is that the machine’s safest ranges are under 150,000 (converts to <50ug/m3). Lower readings are even safer, since pollution’s dose-dependent damage starts above 20ug/m3. OK, back to the findings!

• Mountain air is not necessarily cleaner than urban air. On October 31 we went to lovely Tanzhesi, the temple complex in the western hills only 1 hour west on route 108. Downtown 3rd ring wasn’t awful, at 160,000. You would think “clean mountain air”, right? But surprise surprise, at the base of the hill it was already 350,000, and 3 hours later, after leaving the temple, it was 520,000 in the hills! The main culprit today was definitely hazy skies from both burning autumn leaves as well as cheap coal in rural homes. Perhaps, in the summer, the mountain air may actually be safer, but all winter, of course, those sulfur-laden coal bricks are keeping rural residents warm. I bet their indoor air is even worse, due to the coal.
• Ring road and canal-side pollution was the same. I was also disappointed that my canal-side roads had the exact same pollution levels as the ring roads. I had always assumed that there’d be some type of 50-meter protection, but alas this was not reality. But, on the reverse side, pollution levels directly on ring roads were not higher than nearby roads. But before you get too excited about that, don’t forget that there are other pollution indicators that I didn’t monitor, such as carbon monoxide and nitrogen oxides, which are probably much higher along ring roads, coming directly from car exhaust. Bottom line? I would still recommend your outdoor strolls along the tree-lined canals instead of ring roads, if only for aesthetics and sanity, but perhaps the pollution is the same. Sigh…
• Upper floor pollution was the same as ground floor. Again, I had thought (hoped?) that one could live “above” the worst pollution. Alas, this also was disproved. My 22nd floor apartment had exactly the same PM readings as ground floor.
• Indoor air is almost always better than outdoor air — but still unhealthy. I say “almost always better”; only inside Solana was the air worse. Otherwise, indoor air keeps the worst pollution at bay, and readings were usually 50% of outdoor air. I think indoor pollution is much worse in poorer, rural neighborhoods — anywhere with indoor coal/wood stoves as well as smokers. But, indoor air was still almost always in an unhealthy level. Why? Because Beijing’s air, usually around 140ug/m3, is about 7 times higher than the safety level of 20ug/m3; so, indoor air at half that is still 3-4 times higher than safe.
• Morning air is not always the best time of day. I had previously mentioned that morning air may be the best time for that jog; but my data and other website data now leads me to believe that the cleanest times are early afternoon. But the overall effect is probably pretty small. However, it still remains true that most PM peaks over night with those diesel construction trucks running around after rush hour.
• Not one day was technically healthy. Every day had outdoor ranges above 100,000, which converts to ~35ug/m3. As I hope is sinking in for everyone, PM readings over 20ug/m3 start to have health effects.
• Some days were really bad. On October 29th the sky was milky-grey and smelled funny; I got readings over 1,100,000 all day. On November 5th I got 1,500,000. On the 29th, the official API was 139; Beijingair 415 “hazardous”.
• Blue skies are still unhealthy. Even with this week’s crystal clear, blue sky post-snow days, I still had readings ~130,000. That converts to ~40ug/m3, which again is above the level of safety.

Um, Any Good News?

Well, I suppose there are some take-home messages. My personal feeling is that air pollution is a serious issue that anyone who lives here for more than 3 years should really assess — especially if you have young children. However, I do feel that we can control a great part of our exposure by controlling our indoor environments. After all, we probably spend 90% of our time indoors at work or home, right? So why not ensure that your indoor air is clean? Good air purifiers can get those PM levels to safe levels. Then, you can literally breathe easier and worry less about that 10% of the time outdoors. I have a previous post which discusses air purifiers.

Previous Posts…

Air Pollution: How Bad Is It, Really?
Air Pollution in China: New Slideshow
Air Pollution: What About Indoor Air?

The Fine Print

Here’s that conversion chart for my particle monitor: