The metropolitan area in the Mexico City Valley, in an environmental crisis, registered five environmental contingencies due to ozone between January and April 2025, surpassing by one the occurrences in the same period of 2024. Experts warn that the worst-case scenario is yet to come: historically critical May reported 16 days with dangerous levels of ozone in 2024, the highest annual peak.
The causes, analyzed in a seminar on air quality in Mexico City, include the dry-hot season (March-July), extreme heat, anticyclonic systems, and human activity.
Dry season and human activity: toxic cocktail
Between March and July, the combination of high temperatures and lack of rainfall in Mexico City accelerates the formation of ozone at ground level. This pollutant, generated by chemical reactions between industrial emissions and vehicular emissions under solar radiation, severely affects respiratory health. “The scenario worsens due to anticyclonic systems that stagnate the air, preventing the dispersion of pollutants,” explained specialists during the seminar.
A structural problem in Mexico City
Mexico City faces an added challenge: its location in a basin surrounded by mountains hampers the air circulation. To this, the heat domes are added, phenomena increasingly “more frequent, intense, and extensive,” according to experts. Between 2016 and 2024, 39 ozone contingencies were recorded, mainly concentrated in the Cuajimalpa, Iztapalapa, and Venustiano Carranza delegations, areas with high vehicular and industrial density.
Urgent solutions: transportation and regulation
The measures to reduce the crisis are clear but require political will: renewing public transportation, regulating freight transport, applying rigorous vehicle inspections, and ensuring clean fuels. “Combating pollution not only improves the air but is a direct climate action,” highlighted the seminar participants. Inaction, they warn, would have irreversible costs: according to the WHO, prolonged exposure to ozone increases the risk of chronic lung diseases.
Decisions that cannot wait in Mexico City
The increase in contingencies in the Valley reflects an alarming trend. With May as a critical month, authorities are in a race against time to implement effective policies. Each day of delay deepens the risks for 9 million inhabitants exposed to toxic air. As the experts pointed out: “The actions we take today will determine whether we breathe hope or emergency in the next decade.”
