SmogRank / World / Chile / Biobio / April 2025

Most unhealthy days in Biobio, Chile, April 2025

12 cities in Biobio, Chile ranked by their share of unhealthy days over the 30 days. The most unhealthy days: Nacimiento, Chile, 22 of 30 measured days. A city needs measurements on 70% of the days to be ranked.

Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.

← Nacimiento 73% 70%0
Every city in Biobio, Chile ranked for April 2025, one column each, ranked by unhealthy days: height is the share of its measured days that were unhealthy, colour its average. Point at it to read a city; tap to open it.
  1. 1Nacimiento
    22 of 30
  2. 2Laja
    12 of 26
  3. 3Curanilahue
    11 of 25
  4. 4Hualpén
    12 of 30
  5. 5Coronel
    7 of 30
  6. 6Los Ángeles
    6 of 30
  7. 7Talcahuano
    4 of 30
  8. 8Tomé
    4 of 30
  9. 9Concepción
    1 of 28
  10. 10Chiguayante
    1 of 30
  11. 11San Pedro de la Paz
    1 of 30
  12. 12Lota
    0 of 29
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, April 2025 · All cities in Chile, April 2025 · Biobio now

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SmogRank, most polluted cities in Biobio, Chile, by unhealthy days, PM2.5, April 2025, smogrank.com/cl/region/biobio/history/2025-04?by=days (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.