September 16, 2010 — A ban on smoking in public places in Scotland, instituted in March 2006, has reduced the rate of hospital admissions for childhood asthma, new research findings suggest.
Daniel Mackay, PhD, from the University of Glasgow, in Scotland, and colleagues reported the findings in the September 16 issue of the New England Journal of Medicine.
According to the researchers, the Smoking, Health and Social Care (Scotland) Act banned smoking in all enclosed public places and workplaces in Scotland as of March 26, 2006.
"The legislation has been extremely successful in its primary aim of reducing exposure to environmental tobacco smoke in public places, such as bars," the authors note. In addition, the legislation has reduced exposure of children to environmental tobacco smoke, despite concerns of smoking being displaced to the home, but it is unclear whether the risk for childhood asthma has also decreased.
The researchers collected routine hospital administrative data and ascertained all hospital admissions for asthma in Scotland from January 2000 through October 2009 among children younger than 15 years.
Before the smoking ban, asthma admissions were increasing by an average of 5.2% per year (95% confidence interval [CI], 3.9% - 6.6%). After the ban, the rate of admissions decreased by 18.2% per year relative to the rate on March 26, 2006 (95% CI, 14.7% to 21.8%; P < .001). Rates were reduced both in preschool and school-age children.
Various factors including age group, sex, urban or rural residence, region, or quintile of socioeconomic status had no effect on the outcome.
Limitations of the study include that only exacerbations severe enough to warrant hospitalization were included. In addition, information regarding individual smoking status was not available; therefore, whether the observed reduction in asthma was a result of reduced exposure to environmental tobacco smoke in the home, reduced exposure to environmental tobacco smoke in public places, a reduction in active smoking among school-age children, or an unrelated cause cannot be determined.
"After the introduction of comprehensive smoke-free legislation, there was a reduction in the incidence of asthma among people who did not have occupational exposure to environmental tobacco smoke," the authors conclude.
They add that the "overall exposure of children to environmental tobacco smoke, measured objectively with the use of salivary cotinine concentrations, has fallen since the implementation of the Scottish legislation."
The study was supported by a project grant from National Health Services Health Scotland. One author reports individual employment by National Health Services Scotland; another chairs the Committee on Medical Effects of Air Pollution for the UK Department of Health. The other authors have disclosed no relevant financial relationships.
N Engl J Med. 2010;363:1139-1145.