Background: In 2005, the Spanish government approved Law 28/2005 on health measures against smoking; this was amended in 2010 by Law 42/2010. Objective: The purpose of this study was to assess the impact of these laws on passive smoking. Methods: Three epidemiological studies were conducted on a representative sample of the population via telephone surveys. The first was conducted prior to the first law coming into force, the second a year after its approval and the third a year after the approval of the second.Results: Six thousand eight hundred people were surveyed in 2005, 3,289 in 2007 and 3,298 in 2011. The first survey showed that 49.5% of nonsmokers were exposed to second-hand smoke (SHS) while by 2007, following the introduction of Law 28/2005, this exposure had been reduced to 37.9% (results previously published in 2008). The 2011 survey, conducted following the introduction of Law 42/2010, showed that just 21% of people were exposed. These data indicate that overall exposure to SHS was reduced by 22% between 2005 and 2007 and by a further 16.9% between 2007 and 2011. The overall impact of Law 42/2010 is estimated to be around 44% and Law 28/2005 around 22%. Conclusion: Legislation introduced in Spain has markedly reduced the exposure of nonsmokers to SHS.