New York City's air quality becomes one of worst on Earth due to wildfires

New York City's air quality was briefly the worst of any city in the world due to a string of Canadian wildfires.

IQAir, a Swiss air quality technology company, measured New York City as having a 196 air quality index at 9 p.m. local time on Tuesday — the second highest AQI at the time was in Delhi, India, and it was at 191. AQI measures various pollutants, including particulates, ozone, nitrogen dioxide, carbon monoxide, and sulfur dioxide. The main pollutant in New York City is fine particulate matter or PM2.5. The current amount of...