MEXICO CITY -- A smoky haze that has blanketed this capital for the past week is fraying nerves, spurring health worries and generating criticism of elected officials.
Authorities ordered Mexico City schools closed Thursday and Friday and urged people to stay indoors, as the photochemical miasma enveloping the metropolitan area, home to more than 20 million, failed to disperse.
Professional soccer games and other outdoor events were canceled as part of an emergency decree imposed on Tuesday, and the city government set driving limits to curb the number of vehicles in circulation. Many pedestrians and cyclists donned surgical masks.
The month of May, before the onset of summer rains, traditionally brings the worst air quality of the year to Mexico City, which lies in a high-altitude valley where vehicular and industrial fumes are trapped. A heat wave and sparse winds have made things worse.
This year, however, authorities say fires raging outside the city have exacerbated the problem as smoke has converged above the city and environs, mixing with a toxic brew of contaminants. Measuring stations have found dangerously high levels of tiny particulates, viewed as especially hazardous because they can damage people's respiratory and cardiovascular systems.
"The officials say, 'Don't leave your homes,' but that's easy for them to say," said Sofia Arredondo Lopez, 39, an architect, who was among many perturbed residents interviewed in recent days. "We have to leave to go to work. I worry about going out with this gray blanket covering the city, but telling us not to leave home is not a solution."
The lingering smog has been a reminder of the late 1980s and early '90s, when Mexico City residents experienced what was labeled the world's most polluted air.
In recent decades, however, controls on emissions and limits on automobile traffic have improved matters, and levels of air pollution in cities in Asia and elsewhere have surpassed those generally found here.
But prolonged bouts of smog in recent years have fanned fears that authorities haven't followed up on the city's initial success in curbing contamination, even as the number of vehicles grows inexorably. This week's haunting images of a city shrouded in a thick haze have reinforced the notion that things are getting worse, not better.
"On Sunday, I went out with my kids to downtown and it looked like the apocalypse," said Maria de los Angeles Cabrera, 41. "It was midday and the city looked gray, dark, with a burnt smell. Our eyes were tearing."