Paris police have lowered speed limits and ordered a halt to trash burning as part of emergency measures triggered by a spike in air pollution — months before the city hosts a major international climate conference.

The police department says Wednesday's order includes a 20 kph (12 mph) reduction in speed limits on highways in the metropolitan area.

It comes after state monitoring agency AirParif reported that air pollution rose to "high" under a European classification system. It said changes in weather, and emissions from agricultural activities and road traffic caused the increase.

Paris experienced a similar spike in air pollution last year that ultimately led to imposed, temporary reductions on the numbers of vehicles allowed to circulate.

The city will host a two-week U.N. climate conference starting in November.