On Thursday, the city's elementary schools were ordered closed and drivers told to stay off the roads in the Mexican capital due to poor air quality. Authorities have also recommended that residents avoid exercising outdoors.
That followed city officials' declaration on Tuesday of an environmental emergency, due to severe air pollution exacerbated by wildfires.
Mexico is a city of more than 21 million people, and it has been plagued by air pollution for decades.
Some residents say they believe officials have been too slow to react to the emergency. But Mayor Claudia Sheinbaum says her administration is working on a comprehensive plan to address not only the current emergency, but air pollution in the long term. She attributes the city's problem to cars, factories, higher temperatures and wildfires.