Worst smog of the year prompts Hong Kong government health warning
Low pressure system sends pollution levels rocketing across the city on the worst day of the year so far for air quality
Hong Kong choked on its smoggiest day of the year so far yesterday as a trough of low pressure left the city coping with pollution that represented a "serious risk" to health.
At 7pm and 8pm, all 12 of the city's general pollution monitoring stations and all three roadside stations recorded pollution levels posing a "very high" or "serious" risk to health. All but two general stations and all of the roadside stations were at level 10+, the highest level on the government's Air Quality Health Index (AQHI), introduced last year.
At 2pm, the Tung Chung general station recorded 24-hour concentration levels of PM2.5 - fine suspended particles small enough to lodge deeply into the lungs - at 128 micrograms per cubic metre, more than five times the maximum safe level set the by World Health Organisation. Ozone concentration hit 269, against a WHO maximum eight-hour mean level of 100.
Watch: How to deal with Hong Kong's smog