Here i wrote a couple of information so hopefully it helps u
Air pollution is one of the most serious environmental issues in Mexico City, thanks to a combination of topography, meteorology and the huge concentration of pollution sources. The city sits in an elevated basin at an altitude of 2,240 m above sea level, hemmed in by mountain ridges to the east, south and west. This topography affects the city's climate in ways that contribute to the problem of air pollution. The basin often comes under the influence of high-pressure systems, with weak winds and persistent temperature inversions. The result is that pollutants are often trapped in the basin.
Most of the pollution comes from the burning of fossil fuels by almost 20 million residents, 3.5 million vehicles and 35,000 industries and services. Air pollution is generally worst in the winter, when rain is less common and temperature inversions are frequent.
