If you pay any attention to those periodic lists of the top cities in the world with the worst air pollution, chances are excellent that you've seen Hanoi, Vietnam's capital city, on the list more than once.
And of course, if you either live there or have ever visited, you probably weren't surprised. More likely, you were just happy to confirm your sneaking suspicion that it's not great for any living creatures that like to, you know, breathe.
As you may or may not be aware, Vietnam is also a nation where two-wheeled transportation is massively popular. There are cars, buses, and trucks on public roads, too, but it's hard to understate the sheer volume of motorbikes you'll see on the road (and the sidewalk), especially if you visit any major city. I've been there; I've seen it in person. The flitting and zooming of untold numbers of small-displacement motorbikes in Hanoi puts even Bangkok to shame.
Put another way, Statista noted that over 65 million motorcycles were registered in the country as of 2020. Just four years later, Agence France-Presse (AFP) estimated the number at closer to 77 million. And the majority of these motorbikes are small-displacement ICE machines.
