After a big improvement in 2018, new data shows China’s war on air pollution is slowing down. A Smart Air analysis of 2019 PM2.5 data for China’s 15 largest cities found that more than half saw worse air quality over 2018. Maps comparing average PM2.5 in December 2018 to December 2019 show a general increase in […]
Month: January 2020
The Data-Backed Most Cost-Effective Office Air Purifier
Can a simple fan and filter really make air purifiers that can clean large offices? Seven years ago, Smart Air started when PhD student Thomas strapped together a DIY air purifier to survive a polluted Beijing winter. Founder Thomas Talhelm‘s first DIY air purifier Thomas published test data on the purifier showing that it […]

How Many Trees Need to Be Planted to Solve Delhi’s Air Pollution?
When Delhi’s air pollution spikes, netizens in the nation’s capital often bring up the solution of planting trees. For instance, this user on the question-answer site Quora asks “how many trees does Delhi need to combat its air pollution problem?” However, environmental research suggests that planting trees are an incredibly inefficient way to reduce Delhi’s […]
