Exclusive | Hidden pollution risk means Hong Kong’s typhoon signal No 1 might be scarier than you think
New findings suggest city’s standby signal coincides with spikes in amount of harmful pollutants making their way south from mainland China
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.
The team reached its conclusion after analysing more than 70 typhoons between 2002 and 2013. The results were replicated again for typhoons up to last year, with the same conclusions.
“We have found a substantial increase in transboundary pollution in Hong Kong whenever a No 1 typhoon [standby] signal is in effect,” co-author Steve Yim Hung-lam, assistant professor at the geography and resources management department, said.
The paper was published recently in the journal Science of the Total Environment.
Under the Observatory’s guidelines, a No 1 standby signal indicates that a tropical cyclone is about 800km from the city.