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Hidden pollution risk means Hong Kong’s typhoon signal No 1 might be scarier than you think

Source(s): South China Morning Post
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By Ernest Kao

Storms given the lowest No 1 signal in Hong Kong’s warning system pose a much greater hazard than strong wind or rain in the form of harmful pollutants blown in from mainland China, a study has revealed.

Chinese University scientists found that an approaching typhoon could raise the inflow of pollutants by anywhere from 17 to 46 per cent, most of it fuelled by northerly air flows from across the border.

[...]

Measurements showed no major difference in local air pollution when a No 1 or No 3 signal was in place. Drops were even recorded when the No 3 or No 8 signals were in effect, due to heavy wind and rain helping to disperse pollutants.

[...]

When a standby signal is in force, transboundary contributions of respirable and fine suspended particulates – PM10 and PM2.5 – sulphur dioxide (SO2), and nitrogen dioxide (NO2) go up by an average of 26, 28, 46, and 17 per cent respectively. All of those pollutants can harm the lungs and respiratory system.

This corresponded with a 6.4 per cent increase in the frequency of level seven readings on the 11-tier Air Quality Health Index (AQHI), denoting a “high” health risk.

[...]

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Trans-boundary air pollution in a city under various atmospheric conditions English

Document links last validated on: 16 July 2021

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Hazards Cyclone, Hurricane and Typhoon
Themes Health and health facilities
Country and region China Hong Kong (China)
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