SmogRank / History / City race

Cities in United States, worst air first, day by day

Each measured city's average over the 30 days to every day since January 2023, worst first. Find your own city to follow it through the race, or keep to one country.

CountriesCities
The 30 days to20 Jun 2023 That day's board

The worst cities in United States for PM2.5 over the 30 days to 20 Jun 2023: New Holland 36.9 µg/m³, Claymont 28.3 µg/m³ and Chester 28.3 µg/m³.

  1. 1New HollandPennsylvania36.9
  2. 2ClaymontDelaware28.3
  3. 3ChesterPennsylvania28.3
  4. 4HarrisburgPennsylvania27.3
  5. 5LancasterPennsylvania27.2
  6. 6PennsaukenNew Jersey26.9
  7. 7BethlehemPennsylvania26.8
  8. 8NorristownPennsylvania26.6
  9. 9LebanonPennsylvania26.5
  10. 10WilmingtonDelaware26.4
  11. 11ElizabethNew Jersey26.4
  12. 12ReadingPennsylvania26.3
  13. 13WyomissingPennsylvania26.3
  14. 14ScrantonPennsylvania26.1
  15. 15AllentownPennsylvania26.0
  16. 16YorkPennsylvania25.5
  17. 17Rose HillVirginia24.8
  18. 18TecumsehMichigan24.8
  19. 19Kennett SquarePennsylvania24.6
  20. 20Lincoln ParkMichigan24.6

+ 726 more cities, 24.4 µg/m³ and below

Not counted on this day, too few days measured: Los Angeles since 25 May 2023.

30 days7 days
GoodModerateSensitive groupsUnhealthyVery unhealthyHazardousWHO 24-hour guideline, 15 µg/m³Fades where it stood: not counted that day

A city's number is its average over the 30 days, shown only when 21 of them were measured (5 of 7 on the 7-day race), the same minimum as the 30- and 7-day boards. A city whose monitors go quiet fades out where it stood rather than sliding down, so a gap never reads as cleaner air. Some large countries are thin or missing because their monitors' licences don't allow reuse. How we rank.

Not covered: the government monitoring networks of China and Turkey, which publish only on their own websites; we are building the readers for them. Most cities there are missing from this board, not clean. Why.