Poor air quality to persist in Hong Kong over the weekend as air mass with pollutants affects city

The air quality in Hong Kong on Friday worsened progressively with the city’s pollution index hitting the highest level of 10+ at nine monitoring stations by evening and posing a “serious” health risk.

By 10pm, the level had dropped to between 8 and 9 at those stations, meaning there was a “very high” health risk from pollutants in the air.

The highest reading at night was at Tai Po, followed by stations such as Central/Western, Causeway Bay, Mong Kok, Eastern, Kwun Tong, Tsuen Wan, Tseung Kwan O and Yuen Long.

Earlier in the day, the Environmental Protection Department issued a warning that air quality would remain bad till next week.

It said light winds were unable to effectively disperse the pollutants in the air.

“The sunshine enhances photochemical smog activity and the formation of ozone and fine particulates, resulting in high pollution in the Pearl River Delta region,” it added.

Ozone is formed when nitrogen oxides and volatile organic compounds – emitted from vehicles, industrial activities and power plants – mix in the air under sunlight. It is closely linked to regional pollution. Sources of volatile organic compounds can come from anywhere within the Pearl River Delta.

Studies have linked prolonged exposure to ozone with damaged lung tissue, particularly among the elderly and children. Pulmonary functions can also be reduced and airways sensitised to other irritants and allergens.

The Hong Kong Observatory said winds were expected to strengthen early next week but till then, pollution levels would remain higher than normal.

Pollution levels also spiked on Wednesday with several stations showing that air quality posed a “serious” or “very high” risk to health.

Conditions only improved later that evening after a thunderstorm, when heavy rain fell across the city.

When the air quality is bad, the elderly, children and people with existing heart or respiratory diseases should reduce or avoid physical exertion and outdoor activities, the department’s notice said.

It also advised employers to assess risks for workers outdoors and take preventive measures.

Additional reporting by Karen Zhang