The interesting thing about AQI is that it's not a proxy for air quality. At least, not in the way that I would think. Sometimes, the air looks clear and has good visibility but my AQI app says it's 100 or thereabouts. And pretty often, it has been the opposite as well. 

I have been kind of hopping between cities through the last few weeks (though not out of my own volition). First up, I was in Dubai and saw a beautiful day where I could see miles and miles but had an AQI of 120. A few days later, I was in Mumbai. There was a slight haze, and the AQI was 70!

AQI itself comes in different shapes and sizes. I have been in that rabbit hole before. There's the American measure, the Indian measure, and then UK/Ireland does their own scale of 10 thingy. I am sure there are a few others as well. All the numbers mentioned above are the American AQI measure. 

Intuitively, I felt air quality was a combination of sight and feel. I can see further and clearer, and I can feel the air is fresher -- that was my internal measure of air quality. My hypothesis has evolved now, and I think this internal AQI measure works **only** if the weather is good. If it's too hot (Dubai summers) or too rainy, it doesn't. 

In my childhood, this used to work for India as well -- but now almost never does. I don't get it. The AQI numbers are moderate, but nothing looks clear. I have been to Bangalore and Mumbai and Kolkata. There is always a slight haze and you can't see anything clearly. For those who wear glasses, the feeling is akin to seeing through dirty, greasy glasses. 

And similarly, except high up in the Himalayas, nothing in India feels fresh when you breathe it in. No matter what the AQI is (Bangalore has had some 40-80 AQI days), it doesn't feel it. I sometimes wonder if it's due to age or lung capacity. 

Good rabbit hole to get into. Especially interesting would be to figure out a custom AQI measure that corresponds to what I subconsciously feel. 

Date: 2026-03-25