I don't understand how the author arrives at the conclusion that "[air quality] is often the most effective health intervention, period".
How do you take that away from the plots? If you're in the US my prime take-away would be to keep your BMI in check.
The first graph shows ~2 deaths per 1000 people per year. Surely more than 2 persons/1000/year die in those countries. What are the causes for the other ~10-15 deaths/1000/year?
Given the information in the article, I don't see anything to support the central thesis about air quality. The reasoning for it is so thin that I have no idea whether it's true or not.