This review strengthens the evidence that legislative smoking bans lead to improved health outcomes for people through the reduction of secondhand smoke. The evidence was strongest for improving cardiovascular health outcomes (such as reduced rates of heart attack) and reducing smoking-related deaths. Effects on respiratory and perinatal health were less consistent.
The review was an update from a 2010 review. Most studies used an interrupted time series or before and after design. This type of study measures the impact of smoking bans using data from national registries, hospital databases or data from population health surveys to follow the health outcomes in a population over time. Since 2010, more countries have introduced national smoking legislation banning indoor smoking in public spaces. Some health effects can only be detected in the long term, so it was important to update the evidence on health effects from exposure to secondhand smoke.
Evidence from this review supports smoking bans for reducing exposure to secondhand smoke and protection of non-smokers from its harmful effects.
Why was this study needed?
Smoking is the main cause of preventable illness and premature death in England. People who breathe in secondhand smoke regularly are more likely to get the same diseases as smokers, including conditions such as lung cancer, heart disease, asthma and low birth weight in babies.
The public health response of introducing legislative smoking bans is to protect non-smokers from the harmful health effects of exposure to secondhand smoke and to provide a supportive environment for people who want to quit smoking.
This Cochrane review updated a 2010 review, which found evidence that introducing legislation to ban smoking in public places reduced exposure to secondhand smoke. The researchers aimed to include more recent studies, with potential to cover research from countries that had introduced smoking bans since the previous review and to look closer at health outcomes.
What did this study do?
This Cochrane review included 77 studies from 21 countries up to February 2015 (65 new studies and 12 studies from the previous 2010 review). Four studies were from England. The review aimed to assess the effect of introducing indoor smoking bans on any measure of health. It also looked at the effect of these bans on smoking behaviours.
A broad range of study designs were included, for example, studies which compared the same area before and after the smoking ban. Studies were included if they looked at legislation that banned smoking completely in all public settings or restricted smoking (18 studies) to designated areas at a national, state or local level (see Definitions). They also had to have a follow-up on smoking of six months after the legislative ban was introduced. Follow-up ranged from nine months to about six years.
Overall, the review was carried out to a high standard so we can be confident in the findings. However, variation between the studies was too high to pool the results in meta-analyses.
What did it find?
Thirty-three of 43 moderate quality studies found introduction of smoking bans significantly reduced rates of heart attacks or acute coronary syndrome. Five of six studies found bans significantly reduced stroke rates.
- Twenty-one low quality studies looked at respiratory health with mixed results. Six of 11 studies found significant reductions in admissions to hospital for bronchitis (chronic obstructive pulmonary disease) and seven of 12 studies found significant reductions in admissions to hospital for asthma.
- Seven very low quality studies found inconsistent results on the health of newborn children.
- Eight of 11 low quality studies found introduction of smoking bans reduced smoking-related deaths.
- Evidence of an impact of introducing smoking bans on how common smoking was in the population (prevalence) and tobacco consumption was inconsistent.
What does current guidance say on this issue?
NICE’s 2015 quality standard on Smoking: reducing and preventing tobacco use states that schools, colleges and healthcare settings do not allow smoking anywhere in their grounds and that any areas previously designated for smoking are removed.
In England smoking is prohibited in public transport, indoor public places and indoor workplaces including work vehicles. The ban has been in place throughout the UK since July 2007. In England it followed smokefree legislation, part of the Health Act 2006, and an equivalent law in Scotland that year. The regulations were changed in Wales and Northern Ireland in April 2007. A further ban was introduced in October 2015 that prevents smoking in cars and other vehicles carrying children.
The UK has ratified the WHO Framework Convention on Tobacco Control which calls for the adoption and implementation of effective measures to provide protection from exposure to tobacco smoke in indoor workplaces, public transport, indoor public places and other public places.
What are the implications?
This review strengthens the evidence that legislative smoking bans lead to improved health outcomes for non-smokers through the reduction of secondhand smoke. The evidence was most consistent for improving cardiovascular health outcomes and reducing smoking-related deaths. Effects on respiratory and perinatal health were less consistent and it may be that longer follow-up is needed to detect changes.
Although many of the studies used statistical methods to control for other factors that may have contributed to the results, changes in health outcomes could be due to other things such as changes in healthcare practice or increases in cigarettes prices.
The UK government has considered implementing bans at national or local levels for places where smoking was previously allowed. Restrictions in some prisons are currently being implemented, for example.
Citation and Funding
Frazer K, Callinan JE, McHugh J, et al. Legislative smoking bans for reducing harms from secondhand smoke exposure, smoking prevalence and tobacco consumption. Cochrane Database Syst Rev. 2016;(2):CD005992.
The Cochrane Tobacco Addiction Group receives funding from the NIHR.
NICE quality standard. Smoking: reducing and preventing tobacco use. QS82. London: National Institute for Health and Care Excellence; 2015.
WHO. WHO Framework Convention on Tobacco Control. Geneva: World Health Organization; 2005.
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