Mexico City is banning some cars from city streets again Wednesday because of the first ozone alert in 14 years.
The Mexican capital, once known for its high smog levels, has managed since 2002 to keep its ozone levels within recommended boundaries, and since 2005 it has managed to keep harmful air particles under control as well. But Mexico City authorities say a recent high pressure system combined with intense sunlight has contributed to elevated pollution levels.
Mexico initially dealt with its pollution issue by discouraging use of cars more than 8 years old, resulting in less traffic on city streets. But a court recently relaxed that rule and experts say traffic has gotten worse.
This week authorities restricted the use of older cars on Monday and Tuesday; for Wednesday, they are banning additional vehicles based on their license plate numbers and stickers.
Mexico City is in a high mountain valley between peaks that can trap pollutants in the city, which is 2,240 meters above sea level. The city's residents have been advised since Monday to limit driving and pollution-causing industrial processes. They have also been advised to stay indoors and avoid strenuous activity outside.