Not one driver is convicted four years after law banning smoking in front of children

None of the cases pursued have produced a guilty verdict.

An anti- smoking charity welcomed the f indings and said it showed the law, which prohibits motorists puffing a cigarette in front of under-18s, was being complied with.

Joseph Carter, head of Asthma UK and British Lung Foundation Scotland, said: “We’re pleased to see such low levels of law enforcement have been needed.

“Smoking in a car can create pollution levels 35 times greater than those deemed safe by WHO and no child should be exposed to this level of harm. We hope the low case number indicates a cul tural shi f t towards smoke-free and clean air for all.”

Local authorities and police have powers to crack down on smoking drivers. Councils can issue fines of up to £1000.

But when the law was brought in, they were told to educate offending motorists rather than enforce fines.

The Scottish Government also told the police that arresting offending motorists should not be a priority.

The law was introduced via a private members’ bill by then MSP Jim Hume. The Lib Dem politician, who left the Scottish Parliament in 2016, lost his mum to cancer caused by second-hand smoke.

COPFS sa i d : “Ca r e f u l consideration is given to any reports of alleged criminal conduct which are submitted by the police.

“Action will be taken if the report contains suf f icient evidence in law and it is in the public interest to do so.”

Police said: “The numbers of those being found in breach of the legislation are extremely low but we continue to urge the public never to smoke while in a vehicle with a young person.”