In my experience, the crackers themselves have gotten worse. There's more colour and sound now, and I don't remember them producing so much smoke back in the day. I used to be an avid arsonist as a child despite my asthma being worse then. Now I just can't stand being outdoors.
When it comes to Dehli, from what I've read, the problem is that the crackers tips it over. Post monsoons fog starts building up and it traps all the smoke creating deadly smog. It's just bad timing.
They compensate elsewhere?