Bad-air episodes in Mexico
9 times since January 2023, many cities in Mexico had air at least twice as dirty as their usual for the time of year on the same days. The largest reached 61 cities: Western United States, September 2023.
2023
- Western United States, December 202324 to 29 December 2023, 6 days32 cities71Phoenix
- Southern Mexico, December 202325 December 2023, 1 day10 cities143San Francisco Tlalcilalcalpan
- Western United States, November 20234 to 5 November 2023, 2 days8 cities308Calexico
- Western United States, September 202319 to 24 September 2023, 6 days61 cities48San Jose
- Southern United States and Mexico, June 202313 to 18 June 2023, 6 days18 cities63Ciudad Benito Juárez
- Guanajuato and Jalisco, Mexico, June 202317 to 18 June 2023, 2 days10 cities75Tlaquepaque
- Northern Mexico and United States, May 20236 May 2023, 1 day8 cities74Ciudad Benito Juárez
- Guanajuato and Jalisco, Mexico, May 20233 to 5 May 2023, 3 days8 cities65Guadalajara
- Southern Mexico, January 202318 to 20 January 2023, 3 days10 cities61Guadalajara
Each row: one bar per day, as tall as the number of cities counted that day and coloured by their median level; the number of cities; the highest daily reading and where. An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes.