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Latest Annual AQI

The Annual Air Quality Index (AAQI) is the ratio of the past 12-month rolling average concentration to the annual air quality guidelines (AQG) of the World Health Organization (WHO).

Air Pollutant Concentrations (μg/m3)
Period: November 2020 - October 2021

General Stations

StationNO2PM10PM2.5
Central/Western332616
Southern302613
Eastern353015
Kwun Tong473317
Sham Shui Po472914
Kwai Chung512616
Tsuen Wan432516
Tseung Kwan O252413
Yuen Long373116
Tuen Mun433720
Tung Chung262616
Tai Po322716
Sha Tin302614
North352615
Tap Mun102514
Pollutant concentrations in micrograms per cubic metre (μg/m3)

Roadside Stations

StationNO2 PM10PM2.5
Causeway Bay714024
Central683119
Mong Kok693119
Pollutant concentrations in micrograms per cubic metre (μg/m3)

Annual AQI Values
Period: November 2020 - October 2021

General Station

StationNO2PM10PM2.5
Central/Western0.831.301.60
Southern0.751.301.30
Eastern0.881.501.50
Kwun Tong1.181.651.70
Sham Shui Po1.181.451.40
Kwai Chung1.281.301.60
Tsuen Wan1.081.251.60
Tseung Kwan O0.631.201.30
Yuen Long0.931.551.60
Tuen Mun1.081.852.00
Tung Chung0.651.301.60
Tai Po0.801.351.60
Sha Tin0.751.301.40
North0.881.301.50
Tap Mun0.251.251.40
AAQI = 12-month rolling concentrations/Annual WHO AQG concentration

Roadside

StationNO2PM10PM2.5
Causeway Bay1.782.002.40
Central1.701.551.90
Mong Kok1.731.551.90
AAQI = 12-month rolling concentrations/Annual WHO AQG concentration

Remarks:

(1) The AAQI is updated monthly. The AAQI is calculated based on validated monitoring data.

(2) An AAQI greater than one indicates that the health risk resulted from long-term exposure is higher than that of the WHO's annual AQG, whereas an index below one means a lower risk.

(3) WHO’s annual AQG (2006):


Annual WHO AQG
(μg/m3)
NO2 40
PM10 20
PM2.5 10

Reference: http://www.who.int/phe/health_topics/outdoorair/outdoorair_aqg/en/index.html

For further information about the annual AQI, please visit the FAQ.

(4) NO2 - nitrogen dioxide, PM10 - respirable suspended particulates, PM2.5 - fine suspended particulates