Hong Kong’s official air quality index failing to warn on deadly health hazard

Paul Stapleton warns that the Air Quality Health Index is creating a false sense of security by consistently failing to consider dangerous levels of PM2.5, the fine particulate matter associated with lung disease

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Haze blankets iconic buildings along Hong Kong’s Victoria harbour on January 8. Photo: David Wong

Published: 11:15am, 12 Jan 2017Updated: 9:53am, 13 Jan 2017

Each morning after waking up, I look out of the window at the clarity of the air and then check two websites that give air pollution readings for Hong Kong.

Admittedly, my first action is very subjective. Air clarity is a crude way to measure pollution levels, especially during months that tend to be foggy. This is why I check the indexes on those two sites. Then, I decide whether to go out for a jog or stay indoors on the treadmill.

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One of the websites is run by the Environmental Protection Department. It makes air-quality forecasts and generates a real-time Air Quality Health Index scaled from 1 to 10+, or “low” to “serious”. The other site is the reputable World Air Quality Index (aqicn.org), which measures only particulate matter less than 2.5 microns in diameter (PM2.5), one-thirtieth the width of a human hair.

These microscopic particles that just hang in the air are known to penetrate deep into our lungs when we breathe. They mostly come from vehicle exhausts, the burning of coal to make electricity and other industrial activities.

Pedestrians try to protect themselves from the roadside pollution in Mong Kok, in August 2012. The lungs of young children are particularly prone to damage by fine airborne pollutants, such as PM2.5. Photo: Nora Tam

They are also known to be hazardous to health, especially of children; PM2.5 is associated with lung diseases, including cancer, as well as cardiovascular disease.

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During the past week, the air pollution forecast on the local TV news each day, presumably taken from the government service, was for “low” to “medium” levels. However, at the World Air Quality Index, PM2.5 levels have been in excess of 100 for several days running. The US Environmental Protection Agency puts the 24-hour and annual standard for PM2.5 at 35 and 15 respectively. Thus, on days when Hong Kong’s Environmental Protection Department was informing the public that the level of air pollution was forecast to be low to medium, the amount of PM2.5 – arguably the mostly deadly pollutant – exceeded safe levels by a big margin.