SmogRank / World / Switzerland / May 2025

Most people breathing unhealthy air in Switzerland, May 2025

2 cities in Switzerland measured at 2 or more places, ranked by how many people breathed unhealthy air on an average day over the 31 days. The most people breathing unhealthy air: Zürich, Switzerland, about 18.1K on an average day. A city needs measurements on 70% of the days to be ranked.

About 18.1K people in these 2 cities breathed unhealthy air on an average day of May 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.

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 · Switzerland now

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Ranked cities in each region, May 2025.

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SmogRank, most polluted cities in Switzerland, by people breathing unhealthy air, PM2.5, May 2025, smogrank.com/ch/history/2025-05?by=people (accessed 10 Oct 2026). Some readings from Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published.

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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.