An aerial photo shows boats sailing through Victoria Harbour (center) as residential and commercial buildings on Hong Kong island (foreground) and the district of Kowloon (back) are shrouded by a thick cloud of pollution on Oct 26, 2018. (ANTHONY WALLACE / AFP)

Hong Kong — Hong Kong’s environmental authorities have warned that the Air Quality Health Index (AQHI) in Hong Kong may reach the “serious” level later Monday, according to a press release issued by the HK Special Administrative Region government on Monday. 

The city’s Environment Protection Department (EPD) recorded a gradual increase in pollution levels since Monday morning as the financial hub is under the influence of a high background pollution airstream

The city’s Environment Protection Department (EPD) recorded a gradual increase in pollution levels since Monday morning as the financial hub is under the influence of a high background pollution airstream. 

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The Air Quality Health Index (AQHI) is a pollution evaluation system used by the EPD to provide hourly updates. AQHIs are reported on a scale of 1 to 10 and 10+ and are grouped into five health risk categories of "Low", "Moderate", "High", "Very High" and "Serious”.

When the AQHI reaches 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.

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According to the Hong Kong Observatory, a cold front over inland Guangdong is moving southwards gradually and is expected to move across the coastal areas on Monday evening with strong winds. The air condition will be improved by then.