Cars with idling engines

(The message below was sent recently to the Head Teacher of Great Kinghill school:)

I write as a resident of Cryers Hill.

I would like to draw to your attention the preponderance of vehicles parked at school drop off/collection times which keep their engines running for considerable periods while stationary. This occurs mostly in the car park of the White Lion pub, but also on the grass verges in the vicinity.
The parents involved may not be aware that this now an offence, but they are surely familiar with the dangers of increased air pollution, which impacts directly on children’s health as well as that of the residents in the area. The contribution to greenhouse gases/climate change is also well documented. The RAC article, to which I supply a link below, describes this particularly well.
I wonder if you and your staff could find time to bring this to the attention of both parents and children, and ask them to switch off their engines when parked for more than a few seconds.  I hope it will not be necessary to ask the overstretched police to take action.
Yours hopefully