Air purifiers work best in a closed room environment and this worries some who are concerned that there wouldn’t be enough oxygen coming in when all doors and windows are closed. Yet recent tests in a real apartment — with as many as seven people in a small room — show less than 1% change in oxygen […]
Author: Thomas Talhelm

New Data Shows Beijing’s Air Pollution Progress Reverses in March
After several months of progress cutting PM2.5, Beijing saw a sharp reversal this March, according to the latest data. In years past, Beijing’s particulate pollution normally peaks in January and decreases each month closer to summer. However, this year has seen the exact opposite trend, with PM2.5 increasing 265% from January to March. […]

Truth or Bullshit: Eating Broccoli Protects Against Pollution
Although many natural remedies are based more on intuition than science, a surprisingly rigorous set of studies from different research labs is finding that eating broccoli helps our bodies fight the effects of air pollution. Scientists have isolated the compound thought to help the body remove pollutants like benzene and fight inflammation. The compound, sulforaphane, […]

Smog doesn’t kill like you think it does
The World Health Organization tallied up all the deaths due to outdoor air pollution based on different causes, and the major killer isn’t what most people think. Asthma, lung cancer, and emphysema come to mind when we think about air pollution. But lung problems are only a small portion of the deaths caused by air pollution. […]

Which Indian cities have the best air quality?
Which cities in India have the best and worst air pollution? I analyzed data from the World Health Organization’s database of annual particulate pollution (PM2.5) averages for 122 cities. Here’s what I found. Agra Through Mumbai 122 cities is too much for one graph, so I broke it in half. Here’s A through M from […]

This Data Explains Why You Should Never Use Your Purifier’s Auto Mode
Lots of things in our life are becoming smart. Our phones are smart. Our cars are getting smarter. Purifiers seem like a great candidate for “an education,” but test data shows smart purifiers routinely fail, leaving users with dangerous air. The idea behind smart purifiers’ auto mode is simple. The purifier has a small […]

This Data Explains Why You Should Never Use Your Purifier’s Auto Mode – Supplemental Data
Data and Test Details Test Methods: These tests were identical to my previously published tests, details of which can befound here, here, and here. Original Data: The original data for all 13 tests is available as an Excel file here Average Outdoor PM2.5 During Tests It’s important to note the average outdoor PM2.5 during tests because purifiers achieve smaller percentage […]

Xi’an unveils smog-fighting purifier tower, but does it work?
One group of scientists on the south side of Xi’an are fighting back against Xi’an’s rising PM2.5, and they did so in true China style — by building something big, a huge air purifier tower to be precise. But locals are left to wonder, does it actually work? The air filtering tower might be coming […]

Most Chinese cities cut their PM2.5 in 2017, this city’s air got worse
Now that 2017 is gone, I analyzed PM2.5 in 19 cities all over China, from Harbin to Guangzhou. I then compared 2017 to the prior three years. For most cities, the trend has been flat or down for about three years. The one exception? Xi’an. While most of the rest of China was […]

How bad is the air quality in Kathmandu?
The image in my head of Nepal is full of sky. Nepal has glorious mountains and shining temples. But how’s the air? According to data from the World Health Organization’s global PM2.5 database, Kathmandu’s particulate pollution (PM2.5) averaged 49 micrograms/m3 in 2013: That fits nicely with 2017 data I analyzed from the US […]