There are some good answers here Richard Muller and Sandeep Chowdary. I’ll add a bit more explanation about PM 2.5 AQIs and a funny quirk about how they are calculated using stepwise linear functions. How is PM 2.5 AQI calculated? (Note: this is for the US AQI scale. We’ll be discussing different countries’ scales […]
Author: Thomas Talhelm
Thomas is an Associate Professor of Behavior Science at the University of Chicago Booth School of Business and the founder of Smart Air, a social enterprise to help people in China breathe clean air without shelling out thousands of dollars for expensive purifiers.
PM10 vs PM2.5 – The Difference in Particle Air Pollution
Does size matter? The difference between PM10 and P 2.5 is size. But let me back up. “PM” refers to particulate matter—particles in the air. Those particles are things like organic dust, airborne bacteria, construction dust, and coal particles from power plants (for example, check out this study from researchers in Shanghai who analyzed what […]
What combination of air filters do I need to protect against everything?
This will sound like a grand claim, but two filters are all you need. Here’s why (with data). Very Reasonable Reasons To Be Skeptical Why might you be skeptical? For one, big purifier companies are in an arms race to tell you they have more filters than the next guy. Simpleton Thomas here is […]
Does the Climate in Bangkok Aggravate the Air Pollution in the City?
I just analyzed Bangkok’s PM2.5 data (what is PM2.5?), and I found it varies systematically by season and time of day. Bangkok Average PM2.5 First, some basics. In 2018, Bangkok averaged 27 micrograms of PM2.5. That puts Bangkok just under three times the WHO annual limit. Bangkok’s Air Pollution: The Bad News But […]
Do Air Purifiers Remove PM2.5?
When I was coughing through Beijing’s airpocalypse and thinking about buying an air purifier, I wanted to know something first–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 […]
India Test: Is Indoor Air Just as Polluted as Outdoor Air?
Whether indoor air is just as polluted as outdoor air is an important question for all of the millions of people living in heavily polluted cities. Yet I’ve heard a lot of disagreement about this question. I’ve heard people tell me it’s the same — “indoor air comes from outdoors anyway, so it’s the same.” […]
This One Region in China Saw a Pollution Miracle in 2018
New analysis from Smart Air shows that China is making progress on its “war on air pollution.” PM2.5 air pollution was down in 14 out of China’s 15 largest cities. Yet one region saw far more progress than the rest. South Sees Modest Air Quality Gains In southern China, from Shanghai to Shenzhen, […]
China’s 15 Biggest Cities Saw Better Air in 2018 — Except This One
A new analysis of air quality from 15 of China’s largest cities shows that PM2.5 fell in all cities—except one. From Shenzhen to Xi’an, air pollution was down in 2018. Yet Zhengzhou, capital of Henan province, actually saw pollution rise 7%. With this increase, Zhengzhou now averages over 6 times the World Health […]
Did Beijing’s Air Get Better in 2018?
Analyzing new air quality data, Smart Air found that Beijing’s PM2.5 dropped 14% in 2018 compared to the year before. Despite the improvement, Beijing still averages nearly five times the World Health Organization’s annual limit. Improvement Came Mostly from Winter Enforcement By breaking down the data month by month, analysis shows that the air quality […]
Did China’s Air Get Better in 2018?
New data analysis from Smart Air shows that air quality improved in 14 out China’s 15 largest cities. This data suggests China’s “war on air pollution” seems to be working. This analysis uses over 21,000 daily average PM2.5 data points from official sensors around the country. Beijing Famous for its smog, Beijing’s quality […]