Air Quality Objectives

Hong Kong’s Air Quality Objectives

The Air Pollution Control Ordinance (Cap. 311) sets out Air Quality Objectives (AQOs) and provides for the periodic review of the AQOs at least once every five years with a view to promoting the conservation and best use of air in the public interest. For more information of the review, please visit the website: Review of Air Quality Objectives.

Hong Kong Air Quality Objectives

Pollutant Averaging time Concentration limit [i]  (μg/m3) Number of exceedances allowed

Sulphur dioxide

10-minute

500

3

24-hour

50

3

Respirable suspended particulates (PM10) [ii]

24-hour

100

9

Annual

50

Not applicable

Fine suspended

particulates (PM2.5) [iii]

24-hour

50

35

Annual

25

Not applicable

Nitrogen dioxide

1-hour

200

18

Annual

40

Not applicable

Ozone

8-hour

160

9

Carbon monoxide

1-hour

30,000

0

8-hour

10,000

0

Lead

Annual

0.5

Not applicable

 

Note:

 

[i]
All measurements of the concentration of gaseous air pollutants, i.e., sulphur dioxide, nitrogen dioxide, ozone and carbon monoxide, are to be adjusted to a reference temperature of 293Kelvin and a reference pressure of 101.325 kilopascal.
[ii]
Respirable suspended particulates means suspended particles in air with a nominal aerodynamic diameter of 10 μm or less.
[iii]
Fine suspended particulates means suspended particles in air with a nominal aerodynamic diameter of 2.5 μm or less.

Air Quality Management in Hong Kong

The overall policy objective for air quality management in Hong Kong is to achieve as soon as reasonably practicable and to maintain thereafter an acceptable level of air quality to safeguard the health and well-being of the community, and to promote the conservation and best use of air in the public interest. In this regard, we put in force an updated Hong Kong's AQOs on 1 January 2022 to further protect public health.

The prevailing AQOs are benchmarked against a combination of interim and ultimate targets under the World Health Organization's Air Quality Guidelines (WHO AQGs).  To continuously improve air quality, we have implemented a wide range of measures to control emissions from power plants, industrial and commercial activities, motor vehicles and marine vessels, as well as setting regional emission reduction targets for key air pollutants together with the Guangdong Provincial Government.  

The Government will review the AQOs at least once every five years to monitor the progress of air quality improvement and the effectiveness of measures, with a view to implementing new measures to progressively tighten the AQOs as far as practicable to attain the ultimate targets of the WHO AQGs.

Download the Table of AQOs

Historical AQOs

Air Quality Compliance Status

Air Pollution Control Strategies

 

Related Documents

WHO global air quality guidelines. Particulate matter: (PM2.5, PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide: executive summary (2021)

WHO global air quality guidelines. Particulate matter: (PM2.5, PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide (2021)

WHO Air Quality Guidelines for Particulate Matter, Ozone, Nitrogen Dioxide and Sulphur Dioxide, Global Update 2005

 

Links

Air Quality of Hong Kong

Air Quality Health Index

Air Quality Reports

Mainland China and Overseas Air Quality Objectives/Standards

The Mainland of China

Australia

Canada

EU

Japan

Korea

Singapore

USA

UK

 

 

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