The Environmental Commission of the Megalopolis (CAMe) activated Phase 1 of the environmental contingency on March 18, 2025, due to high concentrations of ozone observed in the Metropolitan Zone of the Valley of Mexico (ZMVM). At 15:00 hours, a maximum ozone concentration of 155 parts per billion (ppb) was registered at the Gustavo A. Madero station.
According to the CAMe's report, the stability of the atmosphere increased significantly around 14:00 hours, leading to very adverse conditions for the dispersion of ozone precursor pollutants. This increase was compounded by intense solar radiation, which has been prevalent in the region, further fueling the formation of ozone from the accumulated pollutants. Furthermore, the prevailing winds have been weak, complicating pollutant dispersion efforts.
Given these conditions, the CAMe initiated the 'Doble Hoy No Circula' program, meaning that specific vehicles will be restricted from circulating in the ZMVM on Wednesday, March 19, 2025, from 5:00 to 22:00 hours. The vehicles affected include:
- Private vehicles with verification hologram 2.
- Private vehicles with verification hologram 1, whose last digit is 1, 3, 4, 5, 7, or 9.
- Private vehicles with verification hologram 0 and 00, red sticker, and with plates ending in 3 and 4.
- Vehicles lacking a verification hologram, such as older cars, demonstration vehicles, new vehicles, those with tourist passes, foreign plates, or plates consisting solely of letters.
- 50% of L.P. gas delivery units that do not possess a dry disconnection valve and have license plates ending in NON.
- Local or federal cargo vehicles, which will be unable to circulate between 6:00 and 10:00 hours on the same day.
- For taxis, those with verification holograms of 00, 0, 1, and 2 must also cease circulation from 10:00 to 22:00 hours.
However, certain vehicles will be exempt from these restrictions, including electric and hybrid vehicles, those holding ecological licenses or exempt holograms, and vehicles needed during medical emergencies. Taxis can circulate from 5:00 to 10:00 hours on restricted days, regardless of their hologram, to support public mobility.
The CAMe emphasizes that the impacts of this environmental contingency are particularly critical due to the current ozone season, which lasts from February to June. During this season, factors such as light winds, humidity shortages, and high solar radiation combine to increase ozone levels, contributing to air quality problems that can adversely affect health.
To safeguard public health during this contingency, the CAMe advises residents to minimize outdoor activities, postpone outdoor events—including sports, cultural, and large-scale gatherings—especially between 13:00 and 19:00 hours. Sensitive groups, notably children, the elderly, pregnant women, and those with respiratory or cardiovascular conditions, are urged to take extra care.
Additionally, residents are encouraged to check for gas leaks in heaters and stoves, consume foods that bolster respiratory health, including citrus fruits, vegetables, and nuts, and to refuel their vehicles outside of peak hours when pollution is typically lower.
The CAMe remains vigilant regarding air quality and meteorological conditions, planning to release further reports about pollutant levels and forecasts. As part of their commitment to public health, they focus on dampening exposure to contaminated air and minimizing health risks posed by severe air pollution events like the current ozone episode.
