SmogRank / World / Czechia / Olomouc Region / 2023

Most unhealthy days in Olomouc Region, Czechia, 2023

2 cities in Olomouc Region, Czechia ranked by their share of unhealthy days over the 365 days. The most unhealthy days: Přerov, Czechia, 13 of 273 measured days. A city needs measurements on 70% of the days to be ranked.

OpenAQ's archive, where our readings come from, has almost none for 56 of these 365 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.

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.

  1. 1Přerov
    13 of 273
  2. 2Olomouc
    9 of 338
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

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SmogRank, most polluted cities in Olomouc Region, Czechia, by unhealthy days, PM2.5, 2023, smogrank.com/cz/region/olomouc-region/history/2023?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.