Mexico City authorities have doubled down on the capital’s emergency driving ban, ordering two out of every five private vehicles to stay off the road Wednesday as heavy smog continued to blanket the megalopolis.
Mexico City has struggled since mid-March to contain high levels of ozone, which has risen well above maximum levels recommended by the World Health Organization, prompting the city to declare its first pollution emergencies in more than a decade. High levels of ozone contribute to respiratory problems such as asthma.
Cars are blamed for emitting 90% of the pollutants that led to the ozone buildup. The Environmental Commission for the Megalopolis estimates there are 10 million vehicles in the metropolitan area, where more than 20 million people reside. The area includes the Mexican capital and surrounding suburbs.
Officials had banned every car from hitting the road one weekday each week and one Saturday a month from April through June based on their license plate numbers and regardless of how new the vehicles are or how they fare on emissions tests.
But after an air-quality monitoring station in the city measured ozone at 160 micrograms per cubic meter on Tuesday—the WHO recommends 100 micrograms at most—the environmental commission issued an emergency order forcing twice as many cars to stay off the roads Wednesday.
Critics say that over time such driving restrictions encourage people to own two cars, increasing the number of vehicles in circulation.
Guillermo Rosales, head of the Mexican Automotive Distributors Association, called the broad ban a “perverse incentive” to keep cheap, obsolete and dirty cars in circulation. “We need incentives that favor the renovation and substitution of the vehicle fleet,” he said.
As part of the emergency measures, outdoor recreation is prohibited at schools, and residents with lung and heart disease are advised to stay indoors in the afternoon when ozone levels peak.
The Mexican Institute for Competitiveness, a think tank, estimates that each year in Mexico City 1,823 people die prematurely—before the age of 65—because of air pollution. Gabriela Alarcón, director of urban development at the institute, notes that plenty of residents have ignored advice against exercising outdoors on recent days of elevated pollution, despite widespread public awareness efforts.
Mexico City is prone to smog due to its unique geography. The city sits 7,350 feet above sea level, in a valley surrounded by mountains that can trap air and contaminants amid intense solar rays and high-pressure weather systems.
The metropolitan area is the heart of the country’s economic activity, accounting for more than a fifth of gross domestic product. The urban area has nearly quadrupled in size since 1980, but public transportation infrastructure hasn’t kept pace with that sprawl.
Government data show one of every three daily trips in the megalopolis is made by a private vehicle, while microtransit, such as rides on outdated and often belching shuttle buses, represents more than half of all trips.
Until last summer, Mexico City restricted daily use of vehicles that are more than eight years old. However, the Supreme Court ruled that restriction was discriminatory, arguing older cars should be allowed on the roads if they pass emissions tests. That decision paved the way for 1.8 million vehicles that could be used only a few days each week to potentially circulate all seven days.
Corruption at vehicle emissions-control centers meant owners could pay extra for a passing test. Just last year, authorities shut down 42 errant emissions-testing centers in the metropolitan area for violations.
Emissions controls, widely available credit, and a crackdown on imports of aging vehicles from the U.S. contributed to record new-car sales in Mexico last year, when consumers purchased 1.35 million vehicles, a fifth of those in and around Mexico City.
The newer the car, the better its technology and ability to curb emissions, car industry representatives argue.
“At the end of the day, we’re looking to improve the quality of the air and therefore of course the health of citizens of this megalopolis,” said Eduardo Solis, head of the Mexican Automotive Industry Association, which represents auto makers.
According to Mr. Solis, the average private vehicle in Mexico City is 14 years old, whereas heavy trucks and buses are usually more than 17 years old. In the U.S., the typical vehicle is 11 years old.
Mr. Solis suggested the government focus more on regulating heavy transport, such as forbidding delivery trucks from blocking lanes on busy roads during rush hour, and banning big rigs from traversing the capital during the day.
The Mexican trucking industry chamber, meanwhile, argued its members should be exempt from the ban to avoid bottlenecks in bringing supplies into the city.
The restrictions don’t apply to trucks carrying perishables, public transport, school buses, or electric and hybrid cars.