Researchers at Imperial College London said before the smoking ban was implemented, hospital admissions for children suffering a severe asthma attack were increasing by 2.2 percent per year, peaking at 26,969 admissions in 2006/2007.
The study, published in the journal Pediatrics, found the childhood asthma hospitalizations declined by 12.3 percent. The study also found the smoking ban resulted in the equivalent to 6,802 fewer hospital admissions in the first three years of the legislation.
The trend reversed immediately after the law came into effect, with lower admission rates among boys and girls of all ages. The reductions among children was similar among wealthy and poor neighborhoods, both in cities and in rural areas.
"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," Dr. Christopher Millett of the School of Public Health at Imperial College London said in a statement.
"We think that exposing children to less second-hand smoke in these settings probably played in important role in reducing asthma attacks."