SmogRank / World / Mexico / September 2025

Most people breathing unhealthy air in Mexico, September 2025

14 cities in Mexico measured at 2 or more places, ranked by how many people breathed unhealthy air on an average day over the 30 days. The most people breathing unhealthy air: Santa Catarina, Mexico, about 12.2K on an average day. A city needs measurements on 70% of the days to be ranked.

About 12.2K people in these 14 cities breathed unhealthy air on an average day of September 2025.

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.

← Santa Catarina 12.2K 10K0
Every city in Mexico ranked for September 2025 with monitors in two or more places, one column each, ranked by people breathing unhealthy air: height is people on an average day, colour its average. Point at it to read a city; tap to open it.
  1. 1Santa CatarinaNuevo León
    12.2K
  2. 2PueblaPuebla
    0
  3. 3Ciudad General EscobedoNuevo León
    0
  4. 4Mexico CityMexico City
    0
  5. 5ZapopanJalisco
    0
  6. 6MonterreyNuevo León
    0
  7. 7León de los AldamaGuanajuato
    0
  8. 8TlaquepaqueJalisco
    0
  9. 9AguascalientesAguascalientes
    0
  10. 10CelayaGuanajuato
    0
  11. 11Ciudad JuárezChihuahua
    0
  12. 12TepicNayarit
    0
  13. 13Santiago de QuerétaroQuerétaro
    0
  14. 14Pachuca de SotoHidalgo
    0
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

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, September 2025 · Mexico now

Regions

Aguascalientes 1Baja California 1Baja California Sur 1Chihuahua 1Guanajuato 7Hidalgo 7Jalisco 3México 3Mexico City 1Morelos 2Nayarit 1Nuevo León 5Puebla 4Querétaro 2Sonora 1Tamaulipas 1Yucatán 1

Ranked cities in each region, September 2025.

Use this board

SmogRank, most polluted cities in Mexico, by people breathing unhealthy air, PM2.5, September 2025, smogrank.com/mx/history/2025-09?by=people (accessed 7 Oct 2026).

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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.