Smoking is banned in public places across the UK
The smoking ban in the UK did not lead to children being exposed to more smoking at home, a study has concluded.
One of the main criticisms of the ban in public places was that it could prompt people to swap pubs for drinking at home where they could smoke.
But a Cardiff University study of 3,500 primary school children found hardly any change in smoking exposure.
Anti-smoking groups and the government said the results vindicated the introduction of the ban.
It was introduced in England, Northern Ireland and Wales in 2007 and in Scotland in 2006.
At the time groups such as Forest, the smokers' lobby organisation, suggested it would lead to drinkers shunning pubs for their homes where they could smoke and, as a result, increasing the risk of second-hand smoke exposure for children.
But the study, published in the BMC Public Health journal, concluded that this had not happened.
Researchers took saliva swabs from children aged 10 to 11 before the ban came in and then a year afterwards to test for exposure to second-hand smoke.
The pupils also filled in questionnaires.
The researchers found that there was no significant change in the children's exposure to second-hand smoke.
They said it was good news that parents were not smoking more at home, although they acknowledged it could be interpreted as disappointing that it did not lead to a drop in exposure.
Part of the thinking behind the legislation was that it would encourage more people to quit as well as raising awareness about passive smoking.
Lead researcher Professor Laurence Moore said: "We could have hoped for a fall, and I think what policy-makers now need to do is look at ways of preventing people from taking up smoking in the first place as a way of reducing smoking levels."
There has been little change in smoking rates for the past 15 years with between a fifth and quarter of adults continuing to smoke.
Martin Dockrell, of anti-smoking group Ash, said it was pleasing to see that the critics had been proved wrong.
And a spokeswoman for the Department of Health agreed.
But she added that the government wanted to see less parents smoking at home.
"Exposure to second-hand smoke is harmful, especially to young people. For this reason, we encourage all smokers to make their homes and cars smoke-free, especially if children are present."
But Simon Clark of Forest said: "I want to see more evidence before I am convinced."