Dr James Cant, head of British Lung Foundation Scotland, spoke out after Westminster politicians voted by 376 votes to 107 in favour of outlawing smoking in vehicles with children in.
The Commons has given Health Secretary Jeremy Hunt the power to impose a ban despite the opposition of some MPs, including Deputy Prime Minister Nick Clegg.
Dr Cant, whose charity has campaigned for a ban, said: "This new law will protect thousands of English and Welsh children from the invisible dangers of secondhand smoke. Scottish children deserve the same protection. The way this issue has risen up the political agenda in the past weeks, not to mention the wide support the proposal received in the House of Commons, show that smoking in cars with children present is a real concern."
He said the rest of the country had "thrown down the gauntlet, and now Scotland's politicians must pick it up".
Liberal Democrat MSP Jim Hume is planning to introduce a bill to ban smoking in cars where children are present. More than 30 MSPs from across the spectrum have so far signed it.
AA president Edmund King said: "The dangers from smoking in cars have long been recognised, such as distraction, littering and causing fires."
Simon Clark, director of the smokers' group Forest, said the few people who still smoked in cars would carry on because of the difficulty in enforcing the law.