Bangkok saw some terrible air quality and high PM2.5 levels during the start of 2019, with news reports of schools closing and government limiting car usage. But just how bad is Bangkok’s air quality? I analyzed 2018’s PM2.5 data, provided by the Thailand Government monitor near the Chulalongkorn Hospital in Bangkok, and here’s what I found:
Bangkok’s PM2.5 particulate pollution averaged 27µg/m3 in 2018.
How Bad is That?
Bangkok’s PM2.5 levels for 2018 came in at just under three times the WHO annual limit of 10µg/m3. That’s bad news for lungs in Bangkok. Research has found that even levels around 10 micrograms affect our health. When compared to other major cities in Europe, Bangkok has higher pollution levels than Paris, Berlin, and London.
Bangkok’s Air Pollution: The Good News
But is Bangkok air the worst in the world? Not even close! I’ve coughed through Beijing winters which have been much worse, and by contrast, Bangkok’s air quality isn’t nearly as bad as Beijing’s level.
If we compare Bangkok’s annual pollution levels to Delhi’s (one of the top 10 most polluted cities in the world) we can see that Bangkok’s PM2.5 levels are actually on average around 4 times lower.
Bangkok’s Air Pollution: The Bad News
One problem with the data above is that it’s the average over the year. That obscures much more serious pollution in the winter. In January 2018, PM2.5 levels reached almost 60µg/m3, that’s more than that double Bangkok’s annual average—and almost 6 times the WHO annual limit.
Why is winter air worse in Bangkok? Around the world, winter air tends to be worse because air sticks closer to the surface of the earth due to something called ‘inversion’. In the summer, hotter air rises from the earth’s surface, taking PM2.5 with it. In the winter this doesn’t happen. Thailand’s winter PM2.5 levels are also higher due to the burning season which usually takes place between February and April, although this is an issue that affects the north of Thailand much more.
Bottom line: Bangkok’s air quality is nowhere near the worst in the world, but averages roughly three times the WHO annual limit. Reducing Bangkok’s PM2.5 would bring meaningful benefits to residents’ health.
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Kang Wei is a chemical engineer from the National University of Singapore. He’s currently working on R&D and engineering at Smart Air.
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We’re suffering a bad spell of prolonged unhealthy air at the moment here in Bangkok. It has even been reported by the BBC and New York Times. Pm2.5 has been between 50 and 150 throughout the day for a few weeks now so I expect the 2019 average will be much higher.