The Pearl River Delta Regional Air Quality Index and half-yearly regional air quality reports will be available online at www.epd.gov.hk and www.gdepb.gov.cn from November 30, the Environmental Protection Department says.

The index is calculated and reported daily based on the air monitoring data collected in the past 24 hours. It will be reported at 4pm daily.

Five gradings will be adopted to show the overall ambient air quality in the region. The lower the grading, the better the air quality is.

As for the monitoring network, major air pollutants are respirable suspended particulates, sulphur dioxide, nitrogen dioxide and ozone.

Sixteen monitoring stations are covered, 13 of which are in the Mainland, including Guangzhou, Shenzhen, Zhuhai, Foshan, Zhongshan, Huizhou, Dongguan, Jiangmen, Zhaoqing, Shunde, Huiyang, Panyu and Conghua. The three stations in Hong Kong are in Tsuen Wan, Tung Chung and Tap Mun.