So you’ve found yourself a city with bad air pollution – perhaps you’re in Beijing, Bangalore or Bangkok? Or try Delhi, Ulaanbaatar or Shanghai? You’ve heard of air pollution, but what is it, how does it affect our health and what guide should you follow to keep air pollution from cutting years off your life?
In this article, I’ll guide you through the most important things you should know to protect yourself from air pollution.
The four most important things to know about protecting yourself from air pollution
When I moved to China in 2007, I wasn’t a dummy. I was a college grad, and I knew about air pollution. But I knew almost nothing about how to protect myself from air pollution.
Since 2007, I’ve spent over ten years researching air pollution and answering questions such as whether you can build your own purifier, if masks actually work, and how to survive the smog. In this article, I’ll spare you the decade of research so that in just minutes, you can equip yourself with the four most important things to know about staying safe in the world’s most polluted cities.
1. The Health Effects of Air Pollution
Bad air quality effects wages war on even young, healthy people’s bodies a lot faster (even without noticeable symptoms) and at a lot lower levels than I had ever imagined.
When I look at small particulate (PM2.5) air pollution readings, I sometimes see warnings like this one for Beijing:
How air pollution affects the health of young, healthy bodies
“Unhealthy for sensitive groups?” Well, I’m not a “sensitive group.” I’m young. I’m healthy. So I don’t need to worry. Plus, I’m usually only in those polluted cities in China or India for a few months. I’m probably fine.
Then I saw a study on air pollution where researchers gave real or fake air purifiers to 35 healthy college students in Shanghai — a top polluted city — and tested their blood.
After just 48 hours, those left breathing Shanghai’s smog and air pollution had a war going on inside their blood systems. The health effects of air pollution were obvious — their bodies were raging with inflammation, their blood pressure was up, their blood vessels were constricting, and their blood was preparing to form blood clots.
Yet the students breathing clean, purified air had significantly less damage in their body. For example, the lower air pollution levels they were breathing meant they had less inflammation:.
And the cleaner air meant they had less constriction in their blood vessels:
Another crazy thing about that study is that its biggest effects weren’t in people’s lungs. It was in their blood and inflammation throughout their body. It’s clear: using an air purifier reduced the impacts of air pollution on people’s health.
This hits on an important fact I discovered. Air pollution doesn’t kill like we think it does. When the World Health Organization tallied up air pollution deaths per year, they found that lung cancer only accounted for 14%. Other lung problems like bronchitis were another 14%. So what’s the other 72%—the large majority of air pollution deaths? Heart attacks and strokes. It comes from that war air pollution plays in our heart and blood vessels.
Do even low levels of air pollution affect the health of our body?
The media always reports on those scary air pollution days when the air outside looks like the end of the world – but those are pretty rare – and they’re just talking about one of the most polluted cities like Beijing, Delhi, Shanghai or Mumbai. The air quality in most cities isn’t normally this bad, right?
What’s more, air quality in smoggy cities like Beijing has gotten better in recent years.
All true. But the more studies I read (1, 2, 3), the more I’m convinced that there’s no safe level for PM2.5 air quality levels. One set of scientists used statistics to estimate how many people die each year from air pollution, at different levels of PM2.5 air pollution. Here’s the graph they made:
Take a look at the black line showing total worldwide deaths each year from air pollution. It goes up pretty fast. Even at 25 micrograms, it’s up pretty high. Now here’s where 2017—Beijing’s best year on record—falls on that graph.
Summary: air pollution affects even young, healthy bodies and causes deaths even at low levels of air pollution
This is what all that air pollution facts mean to me: air pollution is waging war on our bodies, even if we don’t have obvious symptoms, even if we’re young and healthy, and even if it’s at levels far below the ones that make the news. If you’re in virtually any city in China, or any city in India, you’re breathing air that is killing people and you need to protect yourself from this harmful air pollution.
2. Protect yourself from air pollution indoors with an air purifier
Solving poor indoor air quality is easy. Purifiers are just fans and filters. Skip the marketing noise. Build your own or buy a low-cost, data-backed purifier. When I started searching for air purifiers, I saw lots of people buying $500 Blue Air’s and $2,000 IQ Air’s. I wondered, does clean air need to be so expensive? Is there any truth to their claims about special technology or imported HEPA filters?
After researching air purifiers, I found out the main ingredient in purifiers — HEPA filters — were invented back in the 1940s.
Fans aren’t expensive either. So I built my own and tested whether it worked.
The results were clear—even a simple DIY purifier removed dangerous PM2.5 from my home.
Air purifiers don’t need to cost you a fortune: simple, cost-effective machines work just as well if not better
My DIY air purifier improved air quality and reduced particulate in my bedroom by 86%. It even captured really small particles below 2.5 microns. You can make your own DIY air purifier for a tiny fraction of what that fancy Swiss machines sell for.
In my tests and other independent tests, there’s basically no correlation between price and effectiveness. Put another way, there are low-cost purifiers that remove just as much particulate as the $1,000 machines.
So, my startup Smart Air designed purifiers that are—you guessed it—just fans and filters. These DIY purifiers cost about $35 in China, India, and the Philippines. Our super strong Blast Minis outperform the $1,000 IQ Air yet cost about $200. Clean air can be simple and cheap.
What you can do to protect yourself indoors from air pollution:
- Make your own DIY air purifier (I’ll show you how in this guide on DIY air purifiers!)
- Order a low-cost DIY purifier or the super quiet Blast Mini air purifier, or:
- or choose any other empirically backed purifier.
3. Protect Yourself Outside with a Simple Air Pollution Mask
I’ve encountered lots of people who are skeptical of pollution masks. People have told me that masks are so thin, there’s no way to capture small particles. Or they do capture small particles, but unless they’re professionally fitted, the pollution leaks in, so they’re basically useless. Even news media outlets repeat this that masks don’t work.
Before I saw the research on masks, I would have guessed they kinda work all right. Turns out masks are wildly more effective than I thought, even against really tiny .007 micron particles, even when regular people are wearing them, and even when measured by physiological outcomes like lower blood pressure and better regulated heart rate. In short, masks are wildly effective.
And just like with purifiers, some of the most effective masks are also the cheapest.
I used to spend US$80 to buy the UK Respro mask in Beijing. Now I spend less than 10% of that to buy 3M N99 masks that are more effective and more comfortable (here’s the data). Avoid the marketing noise.
What you can do: Choose any of the low-cost, scientifically tested masks in the data above. For air-breathers in India, we’ve released open-data tests of masks available in India.
Which masks are the most comfortable? I cover tests of masks and practical considerations like comfort in this answer: What is the best pollution mask for a vacation in China?
4. Test the Air You’re Breathing
If you want to reach real air pollution nerd status, get an air quality monitor and know what you’re breathing. They’re also great for letting you know if your purifier is working. But are they any accurate? Smart Air tested three: the Laser Egg, the Air Visual Pro, and Dylos (left to right).
We compared data from these particle counters to data from the U.S. Embassy in Beijing, which is close to our office:
We ran the machines for six days. Here are the results for the first (72-hour) test outside our office in Beijing:
All three particle counters tracked the official pollution readings really well! On average, they were about 5-9 micrograms off from the official readings.
What you can do to measure air quality in your home:
Order a Laser Egg or Air Visual air quality monitor and discover what’s in the air you’re breathing.
The most important things to know about air pollution – roundup
Bottom Line on air pollution: I take these simple steps to protect myself from air pollution and breathe clean air, then I spend my time enjoying myself when I visit polluted cities like Beijing and Delhi. Clean air is that simple.
Got your own story on fighting air pollution? Share it with us in the comments section below!
Thomas is an Associate Professor of Behavior Science at the University of Chicago Booth School of Business and the founder of, a social enterprise to help people in China breathe clean air without shelling out thousands of dollars for expensive purifiers.