Author: Antonio Da Roza

Date: 5/8/10

Under Part II of APCO, the Chief Executive establishes air control zones for Hong Kong. For each air control zone, the Secretary for Environment establishes Air Quality Objectives (AQOs). [1]

The AQOs are set at a level which “should be achieved and maintained in order to promote the conservation and best use of air in the zone in the public interest”. [1] However, ‘the best use of air’ and ‘public interest’ are not defined in APCO; no reference is made in Part II of APCO to public health. [2]

No external references (international, regional or national standards or authorities in respect of emissions, air quality or health) are required to be referred to in the setting of the AQOs – this may be contrasted with air pollution abatement notices, where “research material results . . .” or “the advice of a medical practitioner” may be referred to. [2]


The AQOs were first established in 1987, based on “references to research results done mainly in the United States”. [3] Compared to current research, the AQOs were established based on very limited knowledge about the impact of air pollution on human health. [4]Most of the estimated bad health outcomes are occurring at levels of pollution which are well below the present AQOs. [5] However, the AQOs have not been updated since their establishment. The Government recently held a public consultation on a review of the AQOs.

There are no express requirements under APCO for the Secretary of Environment to review or update the AQOs. [2] However, in the case of Clean Air Foundation Ltd v The Government of the HKSAR, the judge held that the Secretary for Environment should “not only introduce air quality objectives but to update them whenever necessary”. [6]


The general pattern shows that pollutant concentrations far exceed even the outdated Hong Kong objectives for PM10 and NO2. Even for SO2, the pollutant with the lowest levels relative to the new WHO AQG, the AQG were violated for 35% of the year. [7] The current AQOs are thus unable to protect health from the effects of air pollution. [8]

The Environmental Protection Department (EPD) is not required by APCO to achieve the air quality objectives, and no statutory time limits are set for achievement – hence, they are not standards but only objectives to be met on a best-efforts basis. [2], [9]

The Secretary for Environment may give the EPD directions as to how the AQOs are to be achieved, but is only responsible to achieve the AQOs in respect of electricity works. [2]

The general power to issue air pollution abatement notices does not refer to the attainment and maintenance of the AQOs. Other than the licensing regime in Part IV APCO, there do not appear to be any other powers under APCO for the Government to achieve the AQOs. [2]

The AQOs and other air pollution laws

The AQOs are not consistently or effectively integrated across the different aspects of air pollution regulation. Where the AQOs are integrated, there is no mandatory compliance. Where the AQOs are not integrated, the regulation of air pollution is fragmented over many different laws and enforced by agencies that may not have control of air pollution or protection of health as a priority. [8]

It may be inconsistent with other laws relevant to air pollution, such as the Environmental Impact Assessment Ordinance and the Town Planning Ordinance, if the Air Quality Objectives allow for levels of air pollution that prejudice to health. [8]

The AQOs and the Air Pollution Index

The Air Pollution Index is based on the Air Quality Objectives. In calculating the Index, the Air Quality Objectives are used as a baseline and are equivalent to the Index level of 100 on the Air Pollution Index scale of 0 – 500. [10]

See Also

  1. The Air Quality Objectives consultation
  2. Clean Air Foundation Ltd & Oldham v Government of HKSAR
  3. The Air Pollution Index


  1. 1.0 1.1 s 6, Air Pollution Control Ordinance Cap 311, Laws of Hong Kong; s 7, Air Pollution Control Ordinance, Cap 311, Laws of Hong Kong - last accessed 7/8/10
  2. 2.0 2.1 2.2 2.3 2.4 2.5 ‘A Review of the Air Pollution Control Ordinance for Legal Professionals’, Antonio M. Da Roza, February 2009 - last accessed 7/8/10
  3. ‘Air Quality Objectives Review Public Consultation’, Environmental Protection Department Hong Kong, July 2009 - last accessed 5/8/10
  4. ‘Boomtown to gloomtown – The implications of inaction’, CLSA – Christine Loh, James Paterson, September 2006 - last accessed 5/8/10
  5. ‘The impact of air pollution on population health, health care and community costs’, Department of Community Medicine, HKU, 27 November 2006 - last accessed 7/8/10
  6. Clean Air Foundation Ltd & anor v The Government of the HKSAR (unrep. HCAL 35/2007) – last accessed 7/8/10
  7. ‘Air Pollution: costs and paths to a solution’, Department of Community Medicine, HKU, Department of Community and Family Medicine, CUHK, Institute for the Environment, HKUST, Civic Exchange, June 2006 - last accessed 7/8/10
  8. 8.0 8.1 8.2 ‘Objective: Clean Air’, Antonio M. Da Roza, Hong Kong Lawyer magazine, November 2009 – last accessed 7/8/10
  9. ‘The air that we breathe’, CLSA, April 2005 - last accessed 7/8/10
  10. API & Air Quality, EPD website - last accessed 7/8/10