SmogRank / Hong Kong / Wan Chai / Wan Chai
Wan Chai, month by month
Wan Chai has a measured daily mean on 1,145 days since 1 January 2023. Its worst month was December 2024, at 106 US AQI (37.4 µg/m³), 54th of 2,616 cities on that month's world ranking. Its cleanest was July 2024, at 60 US AQI (14.1 µg/m³). 2025 averaged 77 US AQI (23.3 µg/m³), against 79 US AQI (24.0 µg/m³) in 2024.
Every month since 2023
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
| Month | Why |
|---|---|
| Jul 2026 | 2 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks. |
| Jun 2026 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | 19 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Oct 2023 | 17 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks. |
| Jul 2023 | 19 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 11 with under 18 hours of readings or readings that failed our checks. |
| Jun 2023 | 15 of 30 days measured; a month needs 21. The others: 15 with under 18 hours of readings or readings that failed our checks. |
| May 2023 | 16 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks. |
| Apr 2023 | 19 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 9 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 9 of 31 days measured; a month needs 22. The others: 19 missing from OpenAQ's archive, 3 with under 18 hours of readings or readings that failed our checks. |
| Feb 2023 | 1 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive, 2 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.
Wan Chai's worst months
| Month | US AQI | World rank |
|---|---|---|
| December 2024 | 10637.4 µg/m³ | 54thof 2,616 |
| January 2024 | 9733.9 µg/m³ | 99thof 2,385 |
| December 2025 | 9331.7 µg/m³ | 287thof 3,006 |
| January 2025 | 9231.3 µg/m³ | 83rdof 2,474 |
| January 2026 | 9230.9 µg/m³ | 167thof 2,617 |
| December 2023 | 9130.4 µg/m³ | 63rdof 2,247 |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Wan Chai's worst days
| Day | US AQI |
|---|---|
| 14 Apr 2025 | 17184.5 µg/m³ |
| 16 Feb 2025 | 16270.9 µg/m³ |
| 13 Apr 2025 | 16067.9 µg/m³ |
| 30 Dec 2024 | 15763.9 µg/m³ |
| 2 Jan 2025 | 15561.3 µg/m³ |
| 15 Apr 2025 | 15256.5 µg/m³ |
| 31 Dec 2024 | 14854.7 µg/m³ |
| 31 Dec 2023 | 14854.5 µg/m³ |
| 29 Dec 2024 | 14653.9 µg/m³ |
| 23 Dec 2024 | 14452.8 µg/m³ |
Daily means, the highest since 1 Jan 2023; 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, Wan Chai, Hong Kong, 1 Jan 2023 – 12 Oct 2026. Monitor data from Hong Kong's Environmental Protection Department via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/hk/wan-chai/history (accessed 13 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.
Wan Chai now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 04:07 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).