SmogRank / World / Mexico / January 2023
Most polluted cities in Mexico, January 2023
9 cities in Mexico ranked by their average PM2.5 over the 31 days. Worst: Celaya at 34.6 µg/m³, #48 of 1,225 cities in the world. Cleanest: Heroica Matamoros at 9.3. A city needs measurements on 70% of the days to be ranked.
OpenAQ's archive, where our readings come from, has almost none for 7 of these 31 days. Cities in the United States and Europe have them from the EPA's and the European Environment Agency's own records of the same monitors; elsewhere a city's average is over its other days. Why.
Mexico has 43 cities ranked over the last 30 days, but only 9 here: most of its monitors have no readings for January 2023 in OpenAQ's archive, where ours come from, or too few to rank. Cities missing from this board weren't clean, just not measured.
About 1.24M people in these 4 cities breathed unhealthy air on an average day of January 2023.
Ranked by people: each city's population times its share of unhealthy days, those with a daily mean over 35.4 µg/m³ (US AQI 101+). That is how many people living there breathed unhealthy air on an average day. Only cities measured at 2 or more places at least 3 km apart are ranked: one monitor shouldn't speak for a whole city. Population is the city itself, not its wider metro area.
- 1Mexico CityMexico City 1.07M
- 2CelayaGuanajuato 109K
- 3León de los AldamaGuanajuato 63.2K
- 4Ciudad JuárezChihuahua 0
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
All cities in the world, January 2023 · Mexico now
Regions
Ranked cities in each region, January 2023.
Use this board
SmogRank, most polluted cities in Mexico, PM2.5, January 2023, smogrank.com/mx/history/2023-01 (accessed 7 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.