Idk why but the air quality dropped 3x(300->1200) in the past 2-3 days again in Delhi.
Good thing that the 
has managed to label all anti-pollution protests as "Maoist" so nobody dares to protest anymore since the government can and will throw you in jail for a decade without trial.
Most people don't care and are out enjoying the weekend in this lethal air.
What are the main pollution sources? Lots of small engines with no emissions controls?
Mostly industry, vehicles, construction and stubble burning.
There are no emission controls in place for vehicles except that it's illegal to use cars older than 15 years in the area.
This seems like less of an approach for controlling emissions and more of a "fuck the poor" law.
It is. Top
ministers have huge stakes in vehicle and fuel industry. Recently, the government enforced 20% ethanol blending in Petrol which was directly led by a minister who owns an ethanol company whose stock surged by like 500% before they rug pulled it.
Public Transport is dying in the country and they keep building roads every few months on the same location.
Delhi is also in a valley in a range of low hills, so the wind cannot clear the pollution away. (E.g. Mumbai has more industry etc, but has cleaner air.)