Hong Kong doesn’t come to mind when people think of air pollution. However, the data tells a different story–one that has important implications for Hong Kongers’ health.
Hong Kong’s Air Pollution in Numbers
I just analyzed data on Hong Kong’s pollution data and found that PM2.5 averaged 30 micrograms in 2018. Here’s how that compares to the World Health Organization 24-hour limit and annual limit.
What does that mean for Hong Kong’s air quality?
Based on this data from Berkeley Earth, Hong Kong averages three times the WHO annual limit. That’s bad news for lungs in Hong Kong because studies have discovered that levels around 10 micrograms affect our health.
That also puts Hong Kong higher than major developed cities. Hong Kongers breathe more polluted air than people in major cities like Paris, Berlin, and London.
Hong Kong’s Air Pollution: The Good News
But is Hong Kong air the worst in the world? Not even close! Hong Kong isn’t even close to air quality of Beijing or Delhi.
Hong Kong’s Air Pollution: The Bad News
However, this yearly average obscures the much more serious spikes in pollution, particularly in winter. For instance, PM2.5 spiked up to a heart-stopping 200 micrograms in January and February 2018. That’s about 3 to 6 times of Hong Kong’s average. At the peak, the pollution was 20 times the WHO annual limit.
Why is winter air worse in Hong Kong? Around the world, winter PM2.5 tends to be worse (evidence from India, China, US) because air sticks closer to the surface of the earth. In Hong Kong, the sea breeze also traps pollution inland.
Where Does Hong Kong’s Pollution Come From?
It’s common sentiment that the air pollution in Hong Kong is blown in from mainland China, but is that really the case? Studies show that there are many local sources of air pollution in Hong Kong. Smart Air analyzed what happens to Hong Kong air pollution when the wind blows from different directions to see whether pollution from Mainland China affects Hong Kong’s air quality.
Bottom line: Hong Kong’s air is not the worst in the world but averages three times the WHO annual limit. Winter has spiked to 20 times the limit.
How I Protect Myself in Polluted Cities
Reducing Hong Kong’s PM2.5 would bring meaningful benefits to residents’ health. Residents can take the following measures to protect themselves from air pollution:
- Wear a mask outdoors when PM2.5 is above 10 micrograms (or 25 micrograms as a looser limit); evidence that masks have physiological benefits here.
- Use a purifier at home; placebo-controlled studies of air purifiers have found that reducing particulate indoors prevents harm to blood pressure, inflammation, and immune response—even among young, healthy twenty-year-olds.
Smart Air is a certified B Corp committed to combating the myths big companies use to artificially inflate the price of clean air. To help people living in polluted cities like Hong Kong protect themselves, Smart Air provides empirically backed, no-nonsense purifiers and masks, thereby helping to lower the cost of clean air.
Kang Wei is a chemical engineer from the National University of Singapore. He’s currently working on R&D and engineering at Smart Air.