The ranking of WHO's "Urban Outdoor Air Pollution Database WHO" 20 14 shows that the annual average value of PM2.5 in the Indian capital New Delhi is the highest, at 153. The value of Patna, another city in India, followed closely with 149.

According to WHO data, India accounts for half of the 20 cities with the highest PM2.5 value, and the rest are from countries such as Pakistan and Iran. This database contains the public data of 9 1 country 1600 cities in the world, and the time span is 20/200813 years.

A study published by Davos Economic Forum shows that India has become the country with the most serious air pollution in the world. This survey investigated the environment of 132 countries, among which India ranked last in the "air quality ranking (impact on human health)". This research is conducted once a year, and the environmental performance index is monitored by the Environmental Research Center of Yale University and Columbia University. This study uses satellite data to measure air pollution concentration.

It is reported that India's high concentration of fine particles is the main factor leading to poor air quality, and India's PM2.5 is even five times higher than the maximum limit.

Suspended particles are one of the main causes of acute lower respiratory tract infection and cancer. The World Health Organization found that acute respiratory infection is one of the most common causes of death among children under 5 years old in India.

As far as the overall environment is concerned, India ranks the worst in the world, ranking 125 among 132 countries, just ahead of Kuwait, Yemen, South Africa, Kazakhstan, Uzbekistan, Turkmenistan and Iraq, while its neighbor Pakistan ranks 120 and Bangladesh ranks1/kloc-0.