Carbon footprint and particulate matter are two different issues. The US has an enormous carbon footprint, but the air quality in the US is much better than India's. This also includes densely populated places like Manhattan. Increase in PM2.5, PM10, NO2 and SO2 directly affects and damages the lungs of healthy individuals. Yes the US has a carbon footprint problem, and yes they're atleast trying to solve it. But their citizens aren't choking. People in New Delhi are. Stop trying to conflate the two issues. Long term climate change != particulate matter in the air we breathe, though they're both important.