SmogRank / Alliston / Castlegar
Alliston vs Castlegar: PM2.5 compared
Over the last year, Castlegar's air was about 1.7× as polluted as Alliston's: PM2.5 averaged 11.6 µg/m³ against 6.8, on the 272 days both cities were measured. Castlegar had the dirtier air on 178 of those days, Alliston on 92. Castlegar was over the WHO's daily guideline of 15 µg/m³ on 39 of them, Alliston on 14.
Right now
The last year, day by day
Month by month
Year by year
| Year | Alliston | Castlegar | Days Alliston was worse |
|---|---|---|---|
| 2026 so far | 40 | 58 | 78 |
| 2025 | 39 | 41 | 116 |
| 2024 | 27 | 39 | 42 |
Means in US AQI over the days both cities were measured that year; a year shows once they share 30 such days.
Each city's worst days
Alliston
- 16 Jul 2026195118.0 µg/m³
- 15 Jul 202616981.1 µg/m³
- 17 Jul 202616576.0 µg/m³
Castlegar
- 11 Aug 2026227152.0 µg/m³
- 9 Aug 2026193116.0 µg/m³
- 7 Aug 2026187107.0 µg/m³
Daily means in US AQI, with µg/m³ beside them, since the index stops at its top value, over the days both cities were measured in the last year. Each date opens that day's world board.
Compare either city with another
Alliston
Side by side with Barrie (the nearest), Gujranwala (the world's worst on 30 days).
Castlegar
Side by side with Creston (the nearest), Edmonton (Canada's 2nd worst on 30 days), Gujranwala (the world's worst on 30 days).
Use this page
SmogRank, PM2.5 daily means compared, Alliston and Castlegar, 7 Oct 2025 – 6 Oct 2026, smogrank.com/compare/ca-alliston/ca-castlegar (accessed 7 Oct 2026).
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.
The same rules as every SmogRank figure: reference monitors first, and a day counts with 18 measured hours. How we measure.
Updated 2026-10-07 08:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.