LONDON: Introducing laws banning smoking in enclosed public places can lead to swift and dramatic falls in the number of children admitted to hospital suffering asthma attacks, according to a study in England published on Monday.

Researchers at Imperial College London found there was a 12.3 percent fall in hospital admissions for childhood asthma in the first year after laws against smoking in enclosed public places and workplaces came into effect in July 2007.

Similar anti-smoking legislation has been introduced in many other countries, including in the United States where it has also been linked to a reduction in childhood asthma emergencies.

"The findings are good news ... and they should encourage countries where public smoking is permitted to consider introducing similar legislation," said Christopher Millett from Imperial's school of public health, who led the study.

Asthma affects more than 300 million people worldwide and is the world's most common children's chronic illness. Symptoms include wheezing, shortness of breath, coughing and chest tightness. In Britain, it affects one in every 11 children.

Before the ban on smoking in enclosed public spaces was implemented in England, hospital admissions for children suffering a severe asthma attacks were increasing by 2.2 percent a year, peaking at 26,969 in 2006/2007, the researchers found.

That trend reversed immediately after the law came into effect, with lower admission rates among boys and girls of all ages. There were similar reductions among children in wealthy and poor neighbourhoods, both in cities and in rural areas.

The effect was equivalent to 6,802 fewer hospital admissions in the first three years after the law came into effect, the team wrote in a study in the journal Pediatrics.

"There is already evidence that eliminating smoking from public places has resulted in substantial population health benefits ... and this study shows that those benefits extend to ... childhood asthma," Millett said in a statement.

A study published in 2009 also found the ban on smoking in public places in England led to a swift and significant drop in the number of heart attacks, saving the national health service 8.4 million pounds ($13.3 million) in the first year.

"Previous studies have also suggested that the smoke-free law changed people's attitudes about exposing others to second-hand smoke and led more people to abstain from smoking voluntarily at home and in cars," Millett said.