SmogRank / World / Czechia / Moravian-Silesian Region / January 2023

Most unhealthy days in Moravian-Silesian Region, Czechia, January 2023

3 cities in Moravian-Silesian Region, Czechia ranked by their share of unhealthy days over the 31 days. The most unhealthy days: Ostrava, Czechia, 3 of 29 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 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.

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.

← Ostrava 10% 10%0
Every city in Moravian-Silesian Region, Czechia ranked for January 2023, 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. 1Ostrava
    3 of 29
  2. 2Havířov
    1 of 27
  3. 3Frýdek-Místek
    0 of 26
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, January 2023 · All cities in Czechia, January 2023 · Moravian-Silesian Region now

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SmogRank, most polluted cities in Moravian-Silesian Region, Czechia, by unhealthy days, PM2.5, January 2023, smogrank.com/cz/region/moravian-silesian-region/history/2023-01?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.