Letter: Dirty diesels

Sir: Why do drivers of large diesel-powered vehicles such as vans, coaches and, especially, minibuses leave their engines running when they are stationary?

We've all seen, heard and smelt this while drivers make deliveries, stop for refreshments, await the return of sight-seeing passengers and so on. Is there a technical reason, such as diesel engines being difficult to restart when warm?

If not, in the interests of their own financial well-being, together with the health of the passer-by and the environment, perhaps the operators could issue guidance to their drivers to switch off. It would be much appreciated.

W A WHITE

Maplehurst, West Sussex