With children now back in their classrooms after the summer holidays, mums and dads are being warned they could be fined when when dropping off and collecting their little ones. While leaving the engine running near the school entrance might seem harmless enough, this practice could land parents with penalties reaching £80, while also adding to dangerous pollution levels.

Highway Code Rule 123 reads: "You MUST NOT leave a parked vehicle unattended with the engine running or leave a vehicle engine running unnecessarily while that vehicle is stationary on a public road. Generally, if the vehicle is stationary and is likely to remain so for more than a couple of minutes, you should apply the parking brake and switch off the engine to reduce emissions and noise pollution."

However, it does specify that keeping the motor running is permitted "if the vehicle is stationary in traffic or for diagnosing faults".

Ash Young, from car care firm 1dot, explained: "Idling means keeping your vehicle's engine running while it's not moving, which pumps unnecessary carbon dioxide and nitrogen oxides into the air. Outside schools, that means children are breathing in pollutants at the exact moment they're most exposed."

Councils have ramped up enforcement this year, with penalties beginning at £20 and doubling when left unpaid. Across certain regions, charges can now hit £80. As well as this, more schools are implementing timed restrictions on drop-offs and collections to alleviate congestion, hazardous parking, and pollution.

Studies have found a link between air pollution and respiratory problems, asthma, and poor concentration in young children, issues that schools are eager to address. And with fuel prices remaining steep, idling also squanders money.

If you leave your engine running for 10 minutes each day, you could waste more than a full tank of petrol over the course of a year. To keep children safe, and avoid being fined, parents are advised to make sure kids are ready with their bag and coat prior to drop-off to prevent delays, and to switch off the engine when stationary for more than 30 seconds.

You could also park a bit further away and walk to the school gates to reduce congestion and get some extra steps in.