Mexico City's government ordered traffic restrictions on Tuesday and recommended people stay indoors due to serious air pollution, issuing its second-highest alert warning for ozone levels for the first time in 13 years.
While conditions persisted, residents were better off inside between 1 p.m. and 7 p.m., should refrain from vigorous exercise in the open and curb sporting activities to avoid respiratory problems, the city said in a statement on Monday.
The government said the alert stemmed from an "extraordinary increase" in ozone concentration due to the presence of a high pressure system and intense solar radiation around greater Mexico City, which is home to more than 20 million people.
Not since September 2002 had the city issued a "phase one" pollution warning for elevated levels of ozone.
