In 2013, 13 of the 20 most polluted cities were located in India.  New Delhi, India had a PM2 level of 128 compared to Beijing, China having a PM2 level of only 81.  Since then scientists have started using satellite technology to help them understand the state of air pollution.  India included air quality monitoring systems in urban areas as well.

-Madison Granditzke

https://www.weforum.org/agenda/2016/02/which-country-has-the-worst-air-pollution/