The Environmental Protection Department says degradation of visibility is a problem not only for Hong Kong but the whole Pearl River Delta, given the rapid growth in urbanisation and industrial activities and its associated air pollution.

In response to a report that estimates the impact of air pollution on health with visibility as an indicator, the department reiterated that improvement of air quality topped the Government's environmental agenda.

To improve air quality, the Hong Kong and Guangdong Governments have agreed, by the year 2010, to reduce emissions of sulphur dioxide, nitrogen oxides, respirable suspended particulates and volatile organic compounds respectively by 40%, 20%, 55% and 55% from 1997 emission levels.

The Government has also made proposals to reduce emissions from power plants through the post 2008 Scheme of Control. Achieving the emission reduction targets will yield substantial improvements to air quality.

On the review of Air Quality Objectives, the department said it has been liaising with international experts and organisations on the development of air quality standards objectives. It will take into account the review findings in the US, Europe and World Health Organisation, and on-going local studies, when considering the need and justification for new standards.