Category Archives: Indoor Air Pollution

Indoor Air Pollution

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Air Pollution: How Bad Is It, Really?

pollution2This is definitely one of the top 10 issues that expats discuss, even before they arrive here. Yes, the air quality is an issue, but it’s important to review the facts as well.

Blue Air Days

First, subjectively and objectively, the air is definitely better than it was compared to a year ago. We’ve had a lot of clear days this year! The government stats agree; “blue air days” with a PM10 rating in their safe range under 100 are the best in over 10 years. But let’s talk about how relevant that really is. First, the government uses a “blue air” pollution index using an air particulate size of 10 micrometers (PM10). That’s a tiny particle, but one issue is that this PM10 is not what most countries use as a proper indicator of air pollution, using a smaller size of 2.5 micrometers. Why? Because this size is more easily inhaled deeper into the lungs and therefore probably causes more damage, so is a more accurate barometer of health risks. Also, the government cutoff of PM10 under 150 (or API under 100) as a “blue sky day” still would count in most other countries as unhealthy. The WHO 2005 Guidelines have 20μg/m3 as the cutoff. There’s a general consensus that, while no number is a safe number, a PM10 over 20μg/m3 starts to have health effects. Therefore, saying you have a “blue sky day” with a PM10 level still in the 90’s would be falsely reassuring.

You’ve probably heard recently about the US Embassy’s air monitor, which is on top of their Chaoyang building and takes hourly PM2.5 readings which are put onto their Twitter page, and which is now accessible through the non-Twitter site This is a mildly sensitive issue as it often reports a higher number than the government’s PM10 readings. But, it is important to realize that you cannot compare them apples-to-apples, since the measuring sizes aren’t the same, and the government figures are an average of the multiple Beijing weather stations. Plus, the PM2.5 number is about equivalent to 50% of the PM10 number (i.e., a PM10 of 100 = a PM2.5 of 50). But for me personally, the Embassy numbers are relevant since I live and work in their neighborhood.

Click on image for larger picture
Click on image for larger picture

Can I Jog Outside Or Not?

OK, enough of the intro. In real life terms, there is definitely a risk from air pollution to your health. The underlying damage seems to be the tiny particles getting sucked deep into your lungs and initiating an inflammatory response — and long term exposure has a dose-response increase in chronic bronchitis, lung cancers, and atherosclerotic heart disease. It has been studied extensively, and I have links below to a couple of the best articles. In one recent New England Journal of Medicine study, every 10 microgram per cubic meter decrease in PM2.5 levels increased life expectancy by 0.6 years. Other studies have shown a similar effect; long term exposure to higher levels of particulates can reduce life expectancy by 0.6 to 1.3 years. (read the article and review, linked below).

What level is safe? Well, the WHO Air Quality Guidlines say the average PM10μg/m3 number should be under 20 μg/m3 to stop the increase in mortality. In 2005 (see the above table), Beijing’s average was over 100 μg/m3.

So, how does this affect your daily life? I think you should read these scholarly reviews yourselves, then occasionally monitor the published numbers and make your own conclusions and decisions, especially if you and your children plan to live here more than a few years. If you like to jog and bike, you should avoid all main and ring roads and avoid the worst days, but you certainly shouldn’t stop exercising outside, since the overall benefits far outweigh the risks.

I think one take-home concept is that air pollution is a pro-inflammatory disease, and that you should be extra aware of having an optimum anti-inflammatory lifestyle and diet. That includes the obvious things like not smoking, and exercising at least 150 minutes per week. Your diet should focus on fruits and vegetable, grains, beans, and good fats. But you could also consider supplements and herbals proven to be anti-inflammatory (usually meaning the same as “anti-oxidant”). That includes vitamin C but also omega 3 fatty acids found in some fish, as well as coenzyme Q10 and others. I personally have a daily regimen of 1 gram omega 3 supplement, as well as CoQ10, as well as a morning smoothie including spirulina.  I strongly recommend people think about these types of proactive health measures, not just for air pollution but for overall health.

pollutionWhat About Indoor Pollution? And Air Filters?

Yes, the levels inside your house can also be dangerously high. It’s not just the outdoor pollution; there are many indoor pollutants as well that can build up. That’s why it’s important to open your windows, usually in the mornings (not overnight! Particulate levels are worst overnight) to clean out your house air. This brings up another perennial expat topic; air purifiers. I personally think they are useful, and I have one in my bedroom going 24/7. But not every doctor is convinced that it makes a big long-term difference. You can start to read more information at the US EPA’s Indoor Air website. We’ll leave the fun topic of “which filter is best?” for a later post & discussion…

Resources: A must-read is a 2008 article in Urbane China magazine, written by United Family Hospital ER Dr. Chickering. It’s a PDF file; article called “Air Supply” starts on page 29. Print it and show it to family and friends! You can also check out my previous post on air pollution.

Scholarly Articles:

Pollution: Close Your Windows at Night

Website: AMFIC – Air Quality Bulletin – 空气质量公告.

Beijing’s air pollution has definitely improved over the past year, but there is still a long way to go before they meet WHO criteria for healthy air. The usual standard is to measure particulates in the air; China usually reports the larger size PM10 numbers, while the international standard is more focused on the smaller and more dangerous PM2.5 particles. These can get into the lungs deeper and cause more damage.

PM10 Levels

In either case, the link above, from the Air Quality Monitoring and Forecasting in China group, has an excellent daily pollution forecast. The image above shows the last 24 hours of PM10 — note how the pollution rises after evening rush hour and peaks at midnight. This is from the diesel trucks which are allowed to enter Beijing only  at night to assist the construction sites. That’s why you should not leave your windows open overnight.

The best time in Beijing to open your windows and clear out your household air is in the mornings. And it is important to clean out your indoor air regularly, as there are many dangerous indoor pollutants which can build up. A good habit is to open your windows when you wake up and close them before you leave for work or school.