But it makes me realize it would be very difficult to live somewhere like Delhi where this is a 24/7 phenomenon
Title is a little misleading (at least how I read it) — they were briefly 1st and 3rd due to wildfire smoke. These rankings are very volatile as well — it's only 5 hours after this article was published and the IQAir rankings [0] now have Kuala Lumpur in 4th and Singapore in 14th.