In early June, cities in the Northeast and mid-Atlantic regions of the U.S. were blanketed by smoke from wildfires in Canada, some hundreds of which are still burning. Air Quality Index levels reached nearly 500 in New York City at one point, well into the “hazardous” range. In fact, New York City was briefly the world’s most polluted city during that time. New York does not normally fall in the worst 3,000 global cities for air quality...