>> reporter: after a ban in pubs and cafes, could the car be the next place where smoking is stamped out? the government in northern ireland is already looking at a ban. now ministers in wales have launched a three-year campaign that claims parents are poisoning their children. >> it causes lung problems, heart problems. so there's all manner of evidence showing just how harmful it is. >> reporter: research suggests the concentration of toxins in a smoke-filled car can be 11 times higher than it was in a smoky bar before the ban. tobacco particles can stay in the vehicle for up to two hours. opening the window does little to reduce the risk of breathing them in. if the campaign doesn't persuade enough parents, the welsh government say they would follow it up with a ban. but that could be difficult to enforce and would enrage some campaigners. they argue adults can make their own minds up about the risks of tobacco. >> it's a perfectly legal product, and i think it's quite wrong the way smokers have been treated. the trouble is smokers are fed up being lectured and harassed.