Mexico City issues 6th smog alert after ozone levels spike

Mexico City officials have issued their sixth pollution alert of the year and ordered more cars off the road to reduce emissions.

The alert automatically doubles from 20 percent to 40 percent the proportion of vehicles not allowed to circulate Wednesday.

It was declared Tuesday afternoon after ozone levels rose above 150 percent of acceptable limits.

It also comes with other measures such as restricted activity at some gas stations and factories and a ban on burning solid or liquid materials.

Mexico City issued its first pollution alert in over a decade in March.

Normally one-fifth of the vehicles in the city and surrounding suburbs must stay at home on a weekday.

The pollution spike is due to seasonal weather patterns and the increasing number of cars in the city.