Mexico City is grappling with persistent air quality issues, as the Comisión Ambiental de la Megalópolis (CAMe) continues to enforce a Phase 1 environmental contingency due to elevated ozone levels. This marks the fourth such emergency this year, triggering restrictions on vehicle circulation in the greater metropolitan area of the Valley of Mexico. The measures, designed to mitigate the harmful effects of air pollution, are currently in effect and will impact commuters on Wednesday, March 11th.
The current contingency was activated on Tuesday, March 10th, at 4:00 PM local time, following readings of 159 parts per billion (ppb) of ozone at the Facultad de Estudios Superiores Acatlán (FAC) monitoring station in Naucalpan de Juárez, State of Mexico. Diario de México reports that the CAMe attributes the high ozone concentrations to a strengthening high-pressure system over central Mexico, resulting in atmospheric stability, weak winds, and intense solar radiation. These conditions combine to create an environment conducive to the accumulation of ozone precursors.
Vehicle Restrictions: ‘Doble Hoy No Circula’ in Effect
As a result of the ongoing contingency, a “Doble Hoy No Circula” (Double Today No Circulation) program is in effect. This means stricter limitations on which vehicles are permitted to drive within the Valley of Mexico between 5:00 AM and 10:00 PM on Wednesday, March 11th. The restrictions apply based on vehicle verification holograms and license plate numbers. The program aims to reduce the number of vehicles on the road, thereby lowering emissions and improving air quality.
Specifically, the following vehicles are subject to the restrictions:
- Vehicles with a verification hologram number 2.
- Vehicles with a verification hologram number 1, with a last numerical digit of 1, 3, 4, 5, 7, or 9.
- Vehicles with verification holograms 0 and 00, with a red sticker and a license plate ending in 3 or 4.
- Vehicles without a verification hologram – including older vehicles, demonstration or transport vehicles, new vehicles, those with circulation permits, tourist passes, out-of-state plates, or plates consisting solely of letters – are subject to the same restrictions as vehicles with a hologram number 2.
Further restrictions apply to specific types of vehicles. Liquefied Petroleum (LP) gas delivery trucks are limited to 50% circulation, provided they are not equipped with a dry disconnection valve and their license plate ends in ‘non’. Local and federal cargo vehicles are prohibited from circulating between 6:00 AM and 10:00 AM, with exceptions for those participating in the Mexico City or State of Mexico Self-Regulation Program.
Ozone Levels and Health Recommendations
The Sistema de Monitoreo Atmosférico de la Ciudad de México (Mexico City Atmospheric Monitoring System) forecasts that the high-pressure system will continue to cause poor dispersion of pollutants. Meteorological models indicate that atmospheric stability will remain moderate to strong, with weak winds, and intense solar radiation will continue to contribute to the formation of ozone, resulting in air quality ranging from “Bad” to “Very Bad” throughout the Valley of Mexico. The Diario de México report details that the maximum hourly ozone concentrations reached 159 ppb at the FAC station on Tuesday afternoon.
Authorities are urging residents to accept precautions to protect their health during the contingency. The CAMe recommends avoiding exposure to peak pollution levels between 1:00 PM and 7:00 PM, particularly for vulnerable populations including infants, the elderly, pregnant women, and individuals with respiratory or cardiovascular diseases. Civic, cultural, and recreational activities, as well as outdoor exercise, are also discouraged during this period.
Reducing Emissions: What Individuals Can Do
To aid reduce emissions, residents are advised to avoid using aerosol sprays, paints, and other products containing solvents. Refueling vehicles is recommended after 6:00 PM and before 10:00 AM, and drivers should avoid overfilling their gas tanks. These measures, while seemingly small, can collectively contribute to a reduction in ozone precursors and improve air quality.
The Broader Context of Air Pollution in the Valley of Mexico
The Valley of Mexico has long struggled with air pollution, due to a combination of factors including its high altitude, dense population, and significant industrial activity. Ozone, a secondary pollutant formed by the reaction of sunlight with nitrogen oxides and volatile organic compounds, is a major concern during warmer months. The CAMe, established as part of the Megalopolis Environmental Commission, is responsible for coordinating air quality management efforts across Mexico City and the surrounding states. Information about the CAMe is available on the Mexican government website (gob.mx).
This latest contingency follows a pattern of increasing air quality challenges in the region. The current emergency is the fourth Phase 1 contingency of 2026, highlighting the ongoing need for comprehensive strategies to address air pollution and protect public health. The effectiveness of the “Doble Hoy No Circula” program and other mitigation measures remains a subject of ongoing debate, with some experts arguing for more stringent regulations and investments in public transportation.
Key Takeaways
- A Phase 1 environmental contingency is in effect in the Valley of Mexico due to high ozone levels.
- The “Doble Hoy No Circula” program restricts vehicle circulation based on hologram and license plate numbers.
- Vulnerable populations are advised to limit outdoor activities during peak pollution hours.
- Residents can help reduce emissions by avoiding certain products and refueling responsibly.
The CAMe is expected to provide an update on the contingency status on Thursday, March 12th. Residents are encouraged to stay informed about air quality conditions and follow the recommendations issued by authorities. Further information can be found on the CAMe website and through local news outlets. We encourage readers to share their experiences and perspectives on the air quality situation in the comments below.