Air Pollution: What About Indoor Air?

I’ve previously discussed outdoor pollution, a common worry for expats. Less commonly discussed but possibly more concerning is indoor air pollution. It’s important to realize that a poorly ventilated house can have more dangerous air than outdoor air — especially if a smoker lives there.

Someone (thanks, Liora!) passed along to me . Published in 2008 by Pediatrics journal, I think it’s important reading as well as an excellent review of the data. And there’s a lot of data that shows how indoor particulates of PM2.5, carbon monoxide, sulfur, etc. can often be much higher than outdoor air. And there is also a lot of data showing increased childhood lung disease and asthma; cancer risk; impaired growth and developmental impairment. Fortunately, there’s also good data showing clear improvements in health when aggressive measures are taken, such as cutting out leaded gasoline or shutting down local coal plants.

The Main Culprits

In the US, the main concerns of indoor air pollution are radon seeping from the earth, and tobacco particulates. For expats here, the most concerning indoor pollutions include chemicals in building materials, paints and finishings; tobacco; and outdoor air not circulating well. Mold and bacteria are less of an issue here due to the very dry weather, but this can actually become a problem when using winter humidifiers that aren’t cleaned often or properly (good breeding tanks for bugs). For many Beijingers and especially rural Chinese, indoor coal and tobacco smoke are the greatest threats.


As usual, tobacco is one of the most dangerous substances, and probably the easiest to remove (stop smoking indoors!). There is a huge amount of evidence that indoor tobacco, and the 4,000 chemicals from cigarette smoke, has a serious impact on childhood illnesses, both short and long term. It’s estimated that 200 million Chinese, mostly women and children, are at risk from indoor tobacco smoke.


Again, this is a lifestyle issue where you can take personal, empowering control:

  1. To protect others, never smoke indoors yourself and aim to quit smoking, getting help to quit if necessary from competent health professionals
  2. Keep a smoke-free home both to protect your family, guests and household staff, and to reduce your own tobacco consumption if you are a smoker.
  3. Patronise voluntarily smoke-free restaurants, of which there are hundreds in Beijing, and tell them why you appreciate a smoke-free environment.  If a restaurant or bar is very smoky, ask for the non-smoking section, and if that is not smoke-free, tell them that you will come back only when they can offer a smoke-free healthy environment.
  4. Don’t give gifts of cigarettes – this is a gift of sickness and death – and don’t offer cigarettes to others.

You can find other resources on tobacco from the . There is also a lot of data from .

Top Tips For Home

The American Lung Association has , including the tips below on making your home safe:

1) Declare your home a smoke-free zone. Secondhand smoke can cause serious health problems, especially for children. Ask smokers to take it outside.
2) Good ventilation reduces indoor air pollution. Leave doors between rooms open most of the time for better air circulation. Open windows when possible to allow for a good supply of outdoor air. Install exhaust fans in bathrooms to remove moisture and chemicals from the house.
3) Keep humidity levels low with a dehumidifier or air conditioner, as needed. Clean both regularly so they don’t become a source of pollutants themselves. Fix all leaks and drips in the home, as standing water and high humidity encourages the growth of mold and other biological pollutants.
4) To prevent carbon monoxide poisoning, have all fuel burning appliances inspected by a qualified technician once a year. Install a carbon monoxide detector near your sleeping rooms.
5) To keep dust mites and other allergens to a minimum, clean regularly. Wash bedding materials in hot water (at least 130°). Consider replacing carpet with area rugs that can be taken up and washed often.
6) Fit your gas range with a hood fan that exhausts the air outside. Use the fan or open a window when cooking to remove gas fumes.
7) Check commercial cleaning products and pesticides for toxic ingredients, and use according to manufacturers directions. Keep your home well ventilated when using these products. Consider switching to less toxic alternatives.

What About Air Filters?

I was already an air purifier user at home, and after reading these latest academic reviews, I’m even more comfortable with my purchase. There are quite a few choices for air purifiers; you can research the more common models and make your own decisions. I trust a couple websites for consumer reviews: is partly owned by the New York Times and has good reviews; and also has reviews (paid website, sign up for free trial). Be wary of many websites which are often biased fronts for manufacturers or retail stores.

More Resources

The about indoor air quality, as well as a. The WHO also has .

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11 thoughts on “Air Pollution: What About Indoor Air?”

  1. says:

Just what i was looking for!


Hi…we're living in Tianjin, and have been following your series on pollution with great interest. We're looking into buying an air purifier and are wondering if you've got any recommendations as to brands that are available locally? Consumer Reports and Consumer Search are good, but don't really cover products that are available here. Especially since we've got our 6 month old here with us, we really need to get one of these soon!!!:)

  1. I love your blog as well, very fun! As for air purifiers, I have three brands that I bought here in Beijing, and all are imported. At home I have a BlueAir 501 and an IQAir 250. Both brands I believe are excellent for big rooms at home. In my small office I just bought a Hunter 31125 from Sundan electronics store in the Village mall. It’s an American company and Taiwanese made, and also very inexpensive at 1290RMB. Both BlueAir and IQAir have websites for Beijing, just Google them. And I definitely recommend getting them if you have a newborn!


    Thank you so much for the information…we really appreciate your blog, especially as new parents trying to make sure we minimize some of the more negative effects (pollution, etc) of living over here.

  2. This is a very interesting article, thank you. An issue of concern is that although the advice is to open windows to improve ventilation, is this a sensible thing to do in a city such as Beijing with high levels of outdoor pollution. If you have any suggestions it would be much appreciated.

    1. Yes, you should definitely routinely open your windows — on days when the air is good. There are a lot of indoor pollutants and gases from walls and furniture that can build up inside. Usually the best times to open the windows (ie when the outdoor air is best) is mid-morning to noonish. Overnight open windows in general is a bad idea, as the outside air usually is worst due to the construction truck’s diesel exhaust.

  3. Thanks a lot. I am so lucky to find your article while search for information on air purifiers.

  4. Hats off to u Dr for this amazing blog….loaded up with lots of information n very useful one….great relief for health concerned people…Thanks a lot n very brilliant effort…

  5. Amazing blog! It’s been my main source of pollution education since I came to China, congratulations for having such a big impact as an individual!

    I work in a Chinese NGO and suggested to my colleagues to buy an air purifier for the office, since we spend so much time in there every day. We are 5 people working in a small room, so we usually have the window open all the time to get fresh air. My colleagues did buy an air purifier, but they now leave the window open when it’s running because they claim we need the fresh air. I think there is also a cultural issue of thinking that always getting fresh air is healthy (which it would be if the outside air was fresh…). Obviously that doesn’t make the air purifier very effective. What should I advice them? Have the air purifier running until the air gets too thick, open the window for a few minutes and then turn on the air purifier again? Buy a lot of plants for preventing the air to get too thick in the first place?

    Thank you for your advice!


    1. Thanks, Cornelia. In general, since the outdoor air at least here in Beijing is almost always far over 50 AQI, it’s usually not a great idea to keep the windows open. And an air purifier doesn’t “suck out good air” or oxygen that you’d need to “refresh” with opening windows. Opening the window usually almost immediately makes the indoor air skyrocket, and it would take a fww hours for most purifiers to bring air back to lower levels unless you cranked it on high, which usually is too loud. If by “thick” you mean “stuffy”, I can’t really help with that one — sounds like the office needs better ventilation. How about just a regular fan to keep the air moving?


A family doctor's wellness guide for China