Paris cracked down Friday on ageing polluting cars, with vehicles registered before 1997 no longer allowed on the streets from 8:00 am to 8:00 pm on weekdays.

Dozens of police were on duty to warn motorists that driving their old cars would soon land them with a fine of 35 euros ($39).

The move is a part of efforts by Paris city hall to clean up its air, which regularly violates EU norms and is estimated to cut six to eight months off the life expectancy of residents.

Cars older than 10 years are estimated to cause half of the city's air pollution.

A ban on thin plastic bags at checkout counters also went into force on Friday.