Outdoor Smoking Areas: Does the Science Support a Ban?

Inhaling secondhand cigarette smoke (SHS), also known as passive smoking, can cause cancer and respiratory and cardiovascular disease. Indoor smoking is banned at many public places and worksites; at others, smoking areas have been moved outdoors. But is keeping cigarette smoke outdoors enough to dissipate the health risks associated with SHS exposure? A review in this issue of EHP explores the current state of knowledge about outdoor SHS exposure. 2 " Outdoor SHS is an emerging topic in the tobacco control community , " says review coauthor Esteve Fernández, an epidemiologist at the Institut Català d'Oncologia–ICO in Barcelona, Spain. Surveys indicate that public support for banning outdoor smoking has increased in recent years, 3 although some opponents argue that such bans are unsustainable, unduly restrictive, and unsupported by the evidence to date. To impose outdoor smoking laws, tobacco control advocates need " evidence-based results from valid and representative epidemiological studies about levels of SHS in different outdoor areas, " says Fernández. For the current review Fernández and colleagues analyzed data from 18 scientific papers published between 2005 and 2012, which measured SHS exposure at outdoor settings in Europe, the United In most of the studies reviewed, the main marker for SHS was fine particulate matter (PM 2.5). Measured average levels of PM 2.5 ranged from 8.32 μg/m 3 to 124 μg/m 3 at outdoor hospitality venues where smokers were present, and from 4.6 μg/m 3 to 17.8 μg/m 3 at other outdoor settings. Individual point measurements exceeded 1,000 μg/m 3 in some cases. Densely packed smokers, partially enclosed outdoor areas, low wind speeds, and closeness to people smoking all contributed to high levels of outdoor SHS. Smoke-free indoor settings near outdoor smoking areas also had elevated PM 2.5 levels, with mean concentrations ranging from 4 μg/m 3 to 120.51 μg/m 3. Measured levels exceeded the median level for irritation from secondhand smoke PM 2.5 reported for brief exposures. 6 Most studies detected outdoor concentrations of PM 2.5 exceeding 10 μg/m 3 , the annual outdoor average that the World Health Organization sets as the lowest cutoff at which lung cancer and cardiopulmonary deaths are likely to increase 7 —a particular concern for chronically exposed hospitality workers. " Although outdoor SHS levels are more transient than indoor levels, and can quickly drop to background levels in the absence of active smoking, " the authors wrote, " potential health effects of these …