I wondered this same question—do air purifiers really get the small particles of PM2.5? I wondered because I saw lots of air purifier tests on pollen, but pollen is generally 10 microns or larger, whereas I was really concerned about the stuff below 2.5 microns. So I went out and bought a laser […]
Tag: health

How’s the air quality in Bangkok? See the data
Bangkok saw some terrible air quality and high PM2.5 levels during the start of 2019, with news reports of schools closing and government limiting car usage. But just how bad is Bangkok’s air quality? I analyzed 2018’s PM2.5 data, provided by the Thailand Government monitor near the Chulalongkorn Hospital in Bangkok, and here’s what I found: […]

Did Mumbai’s Air Quality Improve in 2018?
Smart Air analysed Mumbai’s PM2.5 air quality data provided by the US Consulate. What we found was that Mumbai’s PM2.5 levels increased 15% in 2018, giving much poorer air quality than the previous year. These higher air pollution levels push Mumbai’s annual PM2.5 average to more than seven times the World Health Organization’s annual limit of […]

Can pollution masks help with India’s air pollution?
Every year when winter rolls around, a billion people in India are left breathing toxic, polluted air when on the streets. Be it in Delhi, Mumbai, Kolkata or Hyderabad, everyone is forced to become experts in a complicated scientific question to cope with the pollution: Do pollution masks work? I’ve heard doubts from smart, skeptical […]

Does AC Bring in PM2.5?
It’s that time of year when Beijing is starting to sizzle, if this person roasting fish on her car is any indication. But air pollution isn’t taking a summer break here. It’s not airpocalypse levels, but the buildings nearby are starting to look fuzzy. That made me wonder. If […]

Do Pollution Masks Really Work?
When a billion people in China (and quite a few expats) woke up to the severe air pollution in almost every city in China, it forced a billion people to become experts in a complicated scientific question: Do masks work? Since then, I’ve given talks with hundreds of people all around China about how to protect […]

Do purifiers depend on the placebo effect, or do they really have health benefits?
I’ve seen people ask if air purifiers depend on the placebo effect or do they actually work. I think this is a good question because we should not confuse the outcomes of (1) objectively reducing pollutants in the air versus (2) health effects. There are two things we know about purifiers and one really […]
NPR got these facts about masks wrong
As wildfires were raging across the American West this summer, NPR ran a story on what people can do to protect themselves from all that air pollution. As a non-expert nerd who has dedicated years to understanding how to live under Beijing’s particulate cloud, I was eager to see what the story got right and […]
Is It True That Masks Last Just One Day?
We posted info and data on our findings on whether masks really can stop pollution. My judgment after reading up on mask tests and testing them myself is that the science is pretty well settled. Masks do work. But there are still mysteries that need answers. Perhaps the biggest mystery out there is how long […]
San Francisco’s Air Pollution
A friend of mine just sent me this map of air pollution in San Francisco from the San Francisco Chronicle. Using the latest PM2.5 data, I created a map for China using the same scale: Based on that scale, China’s best city (which is Haikou, according to the World Health Organization database) would still be double the […]