NEET BIOLOGY

Detailed explanation-1: -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-2: -Metepec was the most polluted city in Mexico in 2021, based on fine air particulate matter concentration (PM2. 5). Throughout the year, the city had an average particulate matter concentration of 28.4 micrograms per cubic meter.

Detailed explanation-3: -These air pollutants are mostly generated from human activities such as burning fossil fuels in power plants and vehicle emissions. In the 80s, there were about 124 cars per 1, 000 residents. Although this number might not seem particularly high, these cars were made in poor quality and ran on very toxic fuel.