Research paper 1Heart Institute, Smoking Cessation Program department, Medicine Faculty, University of S˜ao Paulo, SP, Brazil 2S˜ao Paulo State Center of Surveillance, S˜ao Paulo, Brazil Correspondence to Dr Jaqueline Scholz Issa, Heart Institute, Medicine Faculty, University of S˜ao Paulo, Rua Dr Eneas de Carvalho Aguiar 44, 1 andar Bloco2, CEP, S˜ao Paulo 05403- 000, S˜ao Paulo, Brazil; jaqueline@incor.usp.br Received 28 April 2010 Accepted 27 October 2010 Published Online First 25 November 2010 This paper is freely available online under the BMJ Journals unlocked scheme, see http:// tobaccocontrol.bmj.com/site/ about/unlocked.xhtml 156 The effect of S˜ao Paulo’s smoke-free legislation on carbon monoxide concentration in hospitality venues and their workers Jaqueline S Issa,1 Tania M O Abe,1 Alexandre C Pereira,1 Maria Cristina Megid,2 Cristina E Shimabukuro,2 Luis Sergio O Valentin,2 Marizete M da C Ferreira,2 Moacyr R C Nobre,1 Ines Lancarotte,1 Antonio Carlos Pereira Barretto1 ABSTRACT Background Studies have shown that there is no safe level of secondhand smoke (SHS) exposure and there is a close link between SHS and the risk of coronary heart disease and stroke. Carbon monoxide (CO) is one of the most important components present in SHS. Objective To evaluate the impact of the smoking ban law in the city of Sao Paulo, Brazil, on the CO concentration in restaurants, bars, night clubs and similar venues and in their workers. Methods In the present study we measured CO concentration in 585 hospitality venues. CO concentration was measured in different environments (indoor, semi-open and open areas) from visited venues, as well as, in the exhaled air from approximately 627 workers of such venues. Measurements were performed twice, before and 12 weeks after the law implementation. In addition, the quality of the air in the city during the same period of our study was veriﬁed. Results The CO concentration pre-ban and pot-ban in hospitality venues was indoor area 4.57 (3.70) ppm vs 1.35 (1.66) ppm (p<0.0001); semi-open 3.79 (2.49) ppm vs 1.16 (1.14) ppm (p<0.0001); open area 3.31 (2.2) ppm vs 1.31 (1.39) ppm (p<0.0001); smoking employees 15.78 (9.76) ppm vs 11.50 (7.53) ppm (p<0.0001) and non-smoking employees 6.88 (5.32) ppm vs 3.50 (2.21) ppm (p<0.0001). The average CO concentration measured in the city was lower than 1 ppm during both pre-ban and post-ban periods. Conclusion S˜ao Paulos smoking-free legislation reduced signiﬁcantly the CO concentration in hospitality venues and in their workers, whether they smoke or not. BACKGROUND Several recent studies clearly show that there is no safe level of exposure to secondhand smoke (SHS). The Conference of the Parties to the Framework Convention,1 the WHO International Agency for Research on Cancer,2 the US Surgeon General3 and the UK Scientiﬁc Committee on Tobacco and Health4 all agree that SHS exposure is associated with a range of diseases, including cardiovascular heart disease and many types of cancer. For example, SHS exposure increases the risk of coro- nary heart disease by 25e30% and the risk of lung cancer by 20e30%.3 Previous experiences in other countries and cities show a reduction in cardiovascular events after the implementation of a smoking ban law in those places. This reduction is thought to be mainly associated with a reduction in SHS.5e9 Based on these experiences, the São Paulo state government approved smoke-free legislation in 2009, forbidding the consumption of all tobacco products in enclosed and partly closed collective sites, including public and private places, such as working envi- ronments, cultural establishments, pharmacies, bars, restaurants, movie theaters, theatres, hotels, supermarkets, nightclubs, schools, museums, cabs, banks, health institutions and others. The excep- tion includes private residences, religious cult venues in which the tobacco product is part of the ceremony and sites speciﬁcally and exclusively designated for tobacco consumption. After the smoking-ban law became public, it was necessary to create a campaign named “Tobacco- free and healthy environments” to show the viability of eliminating smoking from indoor and partly closed places, through coordinated actions between the São Paulo State Center of Surveillance and the Consumer Protection Agency. The main objective of this campaign was to visit the hospi- tality venues to inform and solidify behaviour changes that would make feasible the practice of the smoking-ban law. The Sao Paulo State Center of Surveillance was responsible for the measure- ments of CO in the hospitality venues and in their workers. CO is a toxic, odourless, colourless, tasteless and non-irritating gas. CO is one of the most important pollutants in cigarette smoke and is exhaled by smokers during and after having smoked tobacco products. We chose CO as a biological marker of SHS because it is easy to measure, has a good correlation with SHS and it can be measured in both the environment and in the exhaled air of individuals at the same time. The atmospheric concentration of CO is generally below 0.001%, but it may be higher in metropolitan areas. It is formed from incomplete combustion of organic material and hydrocarbon combustion at high temperatures with an insufﬁcient oxygen supply. Other common sources of CO generation include combustion of petroleum derogates by cars and coal ovens. The CO concentration in São Paulo city is monitored by the Environmental Agency of São Paulo (CETESB). When inhaled, CO joins successfully with oxygen in the bloodstream to form carboxyhaemoglobin (COHb). CO can remain in the blood stream for up Tobacco Control 2011;20:156e162. doi:10.1136/tc.2010.037614