SmogRank / World / Chile / Biobio / May 2025

Most unhealthy days in Biobio, Chile, May 2025

13 cities in Biobio, Chile ranked by their share of unhealthy days over the 31 days. The most unhealthy days: Nacimiento, Chile, 31 of 31 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 100% 75%0
Every city in Biobio, Chile ranked for May 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
    31 of 31
  2. 2Laja
    26 of 29
  3. 3Hualqui
    19 of 23
  4. 4Curanilahue
    25 of 31
  5. 5Coronel
    25 of 31
  6. 6Hualpén
    23 of 30
  7. 7Talcahuano
    19 of 31
  8. 8Los Ángeles
    14 of 31
  9. 9Tomé
    12 of 31
  10. 10Chiguayante
    10 of 31
  11. 11San Pedro de la Paz
    10 of 31
  12. 12Concepción
    10 of 31
  13. 13Lota
    0 of 28
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, May 2025 · All cities in Chile, May 2025 · Biobio now

Use this board

SmogRank, most polluted cities in Biobio, Chile, by unhealthy days, PM2.5, May 2025, smogrank.com/cl/region/biobio/history/2025-05?by=days (accessed 7 Oct 2026).

Download top 10 by average (PNG)

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.