Scotland has been feeling the heat at last, but with it the air pollution caused by vehicles.
Such emissions already exceed safe limits in many urban areas and are routinely exacerbated by drivers keeping their engines running while parked.
Some Scottish councils have sought for years to stamp out the practice through a combination of persuasion and penalties.
Now, the East Central Scotland Vehicle Emissions Partnership, of four local authorities, has launched a new offensive - Switch Off and Breathe.
As the campaign puts it, idling engines give drivers 0mpg in fuel consumption while subjecting everyone around the vehicle to continuous fumes and engine noise.
Not only do exhaust gases cause cancer and other illnesses, but the myths that switching engines on and off causes extra wear and increases fuel consumption have been debunked.
Some people justify keeping their engines on in cold weather to stay warm. Ironically, others do the same when it’s hot to keep their air conditioning running - rather than open their windows.
Five years after I revealed Scotland’s first US-style “Verdant Vigilante”, a green campaigner who went around politely asking stationary motorists to switch off in the west end of Glasgow, the scourge seems as prevalent as ever.
Non-caped crusader Eric Kay took his cue from Wall Street counterpart George Pakenham, who, inspired to act by seeing stretch limos outside Manhattan restaurants with their engines running, persuaded thousands of drivers to switch off, becoming a sensation in the process.
Despite Mr Pakenham’s success in New York a decade ago, I fear things may be getting even worse over here - in part because of the increasing use of mobile phones for everything we do.
That, coupled with higher penalties for using handsets at the wheel, may be encouraging more drivers to pull over to answer a call or send a text, while leaving their engines running.
If true, a vital road safety improvement increasing other health and environmental damage would be a very unfortunate side effect.
Among the worst offenders seem to van drivers - both traders and those making deliveries.
Who hasn’t seen one sitting behind the wheel, parked at the side of the road, using their phone, laptop or tablet while their engine still chugs away?
I passed two such vehicles within yards each of other on a Glasgow street yesterday - one from a bakery firm, the other labelled “Highway Maintenance”.
However, the most glaring examples involve vans operated by spin-off companies from the very same councils which have taken a lead in attempting to tackle the problem with publicity campaigns coupled with enforcement measures such as fines for offenders.
More and more vehicles are fitted with stop start features that automatically switch off engines when they come to a halt.
But most of those on the road - my two-year-old car included - aren’t.
That might not be the solution anyway, because I’m told if you’re running several power-hungry features at once, like air conditioning and heated seats, the vehicle will start itself up again.
Depressingly, one motoring expert told me: “I would suggest anyone that addicted to their comfort features is going to be pretty immune to ‘green’ campaigns”.