Health risk category for Air Quality Health Index may reach "Serious" Level

     The Environmental Protection Department (EPD) has recorded higher than normal pollution levels. At noon today (August 22), the Air Quality Health Index (AQHI) at some general and roadside stations had reached 8 or above, corresponding to the "Very High" health risk category.

     Under the influence of Severe Tropical Storm Hato, a continental airstream is affecting Hong Kong. The weather is very hot with moderate west to northwesterly winds. Light winds hindered the dispersion of air pollutants formed during yesterday and led to higher than normal pollution level in the morning. The intense sunshine enhances photochemical smog activities and the formation of ozone, resulting in high ozone concentrations in the Pearl River Delta region. The high level of ozone has promoted the formation of nitrogen dioxide particularly in parts of the urban areas and at the roadside. It is expected that the AQHIs of some general and roadside air monitoring stations may reach the "Serious" level later today.

     According to the Hong Kong Observatory, Hato is expected to be closest to Hong Kong tomorrow morning (August 23). Local winds will strengthen significantly tonight and tomorrow morning. It is expected that pollution levels will remain higher than normal until Hato reaches the south China coast.

     With a health risk category in the "Very High" range or above, children, the elderly and persons with existing heart or respiratory illnesses are advised to reduce physical exertion and outdoor activities to a minimum or avoid such activities. The general public are advised to reduce, or reduce to a minimum, outdoor physical exertion, and to reduce time staying outdoors, especially in areas with heavy traffic. As health effects of air pollutants may vary for individuals, persons who are in doubt or experience discomfort should seek advice from health-care professionals. The public may visit the Centre for Health Protection's website ( for more information on health effects of air pollution and relevant health advice.

     The Education Bureau (EDB) urges all schools to visit the EDB website for appropriate measures to safeguard students' health and take note of changes in the index. The relevant hyperlink is as follows: .

     When AQHI is at the "Very High" level, employers of outdoor workers performing heavy manual work are advised to assess the risk of outdoor work and take appropriate preventive measures to protect the health of their employees such as reducing outdoor physical exertion and the time of their stay outdoors, especially in areas with heavy traffic. At the "Serious" level, employers of all outdoor workers are advised to assess the risk of outdoor work and take appropriate preventive measures to protect the health of their employees.

     Members of the public can check the current AQHI readings at the EPD's website ( or by calling the hotline 2827 8541.

Ends/Tuesday, August 22, 2017
Issued at HKT 12:39