SINGAPORE - Warning letters were issued on Wednesday to 14 motorists who had left their vehicle engines idling while stationary in a three-hour enforcement exercise by the National Environment Agency (NEA) in Ang Mo Kio.

NEA also distributed pamphlets and anti-idling car decals to 236 motorists, as part of the exercise to promote compliance with anti-idling regulations, which NEA officers had found many motorists to be unaware of. Those who left their engines on were workers loading or unloading goods, taxi drivers waiting for customers, parents waiting for school-going children, or simply drivers taking a break in their vehicles.

Under Environmental Protection and Management (Vehicular Emissions) regulations, it is an offence to leave the engine of a motor vehicle running when it is stationary for reasons other than traffic conditions. Those breaching the law can be fined up to $5,000.

In a statement, the NEA urged the public to turn off their engines after parking for better air quality and public health.

"In the last three years, NEA had taken action on over 8,000 cases of idling engines and these comprise issuance of advisories, warning letters and fines to errant drivers," it said.

Those who spot idling vehicles are encouraged to report them, providing the vehicle registration number, as well as location, date, and time of the incident.

They can call the NEA hotline on 1800-CALL NEA (1800-2255 632), or use the smartphone app called myENV. They can also choose to send in videos to contact_nea@nea.gov.sg