Exposición a humo de tabaco ajeno en lugares públicos de la Ciudad de México, Guadalajara y Monterrey

objective. to quantify environmental tobacco smoke exposure in public places in mexico to promote policies of 100% smoke-free environments. materials and methods. in hospitals, schools and public offices of monterrey, guadalajara and mexico city 20% of inner areas were monitored. median nicotine concentrations were estimated by city, type of public space and type of inner area. results. median concentration in areas where nicotine was detected was 0.06 μg/m3 (p25=0.03, p75=0.12 μg/m3). higher concentrations were found in mexico city and in public offices. nicotine was not detected in 75% of monitored areas. conclusions. monitoring environmental nicotine is a useful tool to evaluate compliance of public places with the smoke-free environments legislation, and could constitute an important source of information to strengthen implementation efforts.