SmogRank / Italy / Lombardy / Castano Primo

Castano Primo, month by month

Castano Primo has a measured daily mean on 7 days since 21 January 2026.

Every month since 2026

2026too few days for a mean (a year needs 200)7 days measured
Jan3 daysFebnoneMarnoneAprnoneMay2 daysJun1 dayJulnoneAugnoneSepnoneOct1 day
Each square is a month's mean PM2.5 in US AQI from Castano Primo's measured days, with its place on that month's world ranking under it. A month has a mean once 70% of its days are measured, the rule the monthly rankings use; under that, the square gives the days measured. Each square opens that month's ranking with Castano Primo marked; each year, the year's.
Good0–50
Moderate51–100
Unhealthy for 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

Months without a mean, and why

10 months
MonthWhy
Oct 20261 of 12 days measured; a month needs 9. The others: 1 with no readings from the monitor, 9 with readings for part of the day (a day needs 18 hours), 1 with under 18 hours of readings or readings that failed our checks.
Sep 2026No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jun 20261 of 30 days measured; a month needs 21. The others: 29 with under 18 hours of readings or readings that failed our checks.
May 20262 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks.
Apr 2026No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Mar 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Feb 2026No day measured. The others: 28 with under 18 hours of readings or readings that failed our checks.
Jan 20263 of 31 days measured; a month needs 22. The others: 8 with under 18 hours of readings or readings that failed our checks.

A day counts once 18 hours of it are measured; a month needs 70% of its days.

Castano Primo's worst days

DayUS AQI
21 Jan 2026 9231.1 µg/m³
23 Jan 2026 8125.4 µg/m³
22 Jan 2026 7522.0 µg/m³
31 May 2026 5410.5 µg/m³
28 May 2026 5310.2 µg/m³
10 Oct 2026 111.9 µg/m³
6 Jun 2026 61.0 µg/m³

Daily means, the highest since 21 Jan 2026; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.

Use this history

SmogRank, PM2.5 monthly and daily means, Castano Primo, Italy, 21 Jan 2026 – 10 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/it/castano-primo/history (accessed 13 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.

Castano Primo now: the last 24 hours, its ranks today and the last 12 months day by day.

Updated 2026-10-13 05:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: 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 (why we use them).