I've lived all my life in India. Though have moved around for jobs. Most of my life I have lived in Bangalore. I worked for around 3 years in the US.
While I was in the US, my Asthma kind of magically vanished. In fact I don't even remembering having any respiratory issues of any kind, until in the last 4 months when I caught an infection. When the doctor asked I had show him my unused, now expired Asthma medication. So the doctor suggested my Asthma remission could be due to lack of pollution in the US. In fact despite drinking water while traveling at various places in the US I rarely caught a infection of any kind. Not even a Stomach upset. The 3 years that I lived in US were my healthiest in all life. I didn't take a single pill for anything. In fact that final infection I had didn't warrant medication too.
The moment I came back to Bangalore, my Asthma returned, like on the very third day. Eating out in Bangalore, the throat infections and food poisoning returned. And Bangalore is considered a relatively well off place compared to many cities. But still you see streets littered with garbage, stagnant water. Malaria, Dengue and Chickungunya break outs every few months are very common. Even until recently Dengue was almost like a death sentence in Bangalore.
Every few months there is a lake in around vicinity of South Bangalore(called Bellandur lake) which catches fire. Apart from the industrial waste, a lot of apartments release sewage in the lake, eventually leading to decay, and then Methane release and then fire.
Though I don't have much Idea about North India, from news I learn every day that things are way worse. A couple of months back New Delhi skies blocked out sun for several weeks at a stretch due to Paddy burning.
India needs very urgent laws on the lines of Clean Air Act, and Clean Water Act in US. Too many people are falling ill due to pollution and illness. Apart from the fact that illness is a bad thing, its also a huge drain on economy in terms of health care cost and work place productivity.