Indoor smoking bans draw their ethical authority from extensive research showing harm from prolonged and repeated exposures in homes and workplaces, over many years. By contrast, recent agitation to extend bans to outdoor settings like parks, car parks, beaches, and streets is supported by flimsy evidence. Brief exposures to others’ smoke can produce measurable physiological changes.1 2 However, acute exposure studies typically define brief as 15 to 30 minutes—considerably more than usual smoky encounters outdoors.3

A recent paper concluded that outdoor smoke is rapidly attenuated but for those within half a metre of multiple smokers “between 8 and 20 cigarettes smoked sequentially could cause an incremental 24-hour particle exposure greater than . . . the 24-hour EPA [US Environmental Protection Agency] health-based standard for fine particles.”4 The authors referred to bar patios as where this …