NEET BIOLOGY

Detailed explanation-1: -In 1992, the United Nations declared Mexico City the most polluted city on Earth. By that point, the government had begun to implement policies to confront it, beginning with the Comprehensive Program Against Air Pollution (PICCA) in 1990.

Detailed explanation-2: -It earned the accolade of the world’s most polluted city. A management programme was introduced which introduced reforms that would clean up the air. Levels of ozone were reported to be around 500 parts per billion (ppb), they are now at a more respectable level of between 120 and 150 ppb.

Detailed explanation-3: -Population growth, increasing motorization and industrial activities, a constrained basin and intense solar radiation combined to cause intense air-quality problems of both primary and secondary pollutants.

Detailed explanation-4: -1. Dammam, Saudi Arabia (124.11 µg/m3)

Detailed explanation-5: -Among the most polluted cities with respect to PM2. 5 levels, Delhi (99.71 micrograms per cubic metre) ranked first, Haryana’s Faridabad (95.64 micrograms per cubic metre) ranked second and Uttar Pradesh’s Ghaziabad (91.25 micrograms per cubic metre) third, according to the analysis of CPCB data.