Warmer temperatures, less rain blamed for spike in bad air days in Hong Kong
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Hongkongers endured nearly twice the number of days of unhealthy air last year compared with the previous year, according to government data released on Tuesday.
The increase came as hazardous ozone pollution reached decades-old highs and roadside air quality worsened.
The Environmental Protection Department cited “meteorological conditions” such as more sunshine, less cloud cover and rain, and slightly warmer temperatures for making it more favourable for ozone to form.
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The number of hours when readings on the 11-tier Air Quality Health Index hit “7” or above at monitoring stations equated to 44 days last year, up from 26 days the preceding year.
At roadsides, about 55 days of high-risk air were measured compared with 31 days in 2016, likely because of the 5 per cent rise in harmful nitrogen dioxide (NO2) concentrations at street level and 3 per cent increase in respirable suspended particulates – also known as PM10.
Causeway Bay had the worst air quality, recording 69 days in which air quality index readings were at “7” or higher.
Average annual concentrations of ozone clocked in at 51 micrograms per cubic metre of air last year, a 19 per cent increase since 2013 and the highest level registered in nearly two decades.