Drivers in the borough could face on-the-spot fines if they leave their vehicle engines running outside schools.

The move is part of a drive by Croydon Council to encourage motorists to switch off idling engines and cut air pollution.

Officers will work with schools to ensure the message to improve air quality is understood and under regulations set out in the 1995 Environment Act, will ask that drivers switch off their engines when left running unnecessarily.

A £20 fine will be issued if they refuse.

Since the scheme began in January 2005 more than 100 vehicles have been turned off as a result of the council's enforcement.

Mike Pilgrim, divisional director of public protection, said: "The purpose of the scheme is to improve local air quality for the benefit of local people's health.

"Many drivers don't realise that a car engine idling produces 80 per cent more pollution than one in motion."