alt Hacker NewsBefore people freak out about their morning run, I’m very hard pressed to find 25 PM2.5 on this map of the US. (Note these numbers are AQI, you have to zoom into the bad AQI numbers and look at their PM2.5). Albeit it’s a Saturday morning, not rush hour.
China and India look rough though.
Please note that air quality in an area varies dramatically over time. You are looking at a current snapshot with maps like that. The map linked below has his more historical data and I can see several _weeks_ this past year in my area (which currently has very good air quality) where the PM 2.5 weekly average exceeded 25ug/m^3.
https://map.purpleair.com/air-quality-raw-pm25
Localized phenomena like a neighbor starting a fire, up to the activity of nearby factories and power plants, up to national and global phenomena like wildfires and weather patterns, all have dramatic effects. Looking at an air quality map once and determining that you don’t have to think about air quality because you’re in the US is a mistake.
Exercise outdoors is a wonderful thing, obviously, but there are some days, even in the US, where you might think twice or even consider shifting your exercise to a different (less-polluted) time of the day.