[Impact of the smoke-free legislation on the prevalence and referred time exposure to the environmental tobacco smoke in Zaragoza].

Objectives: To assess the impact of the Law 42/2010, on the health measures on smoking, on the prevalence of the exposure to environmental tobacco smoke (ETS), the repercussions in frequently visited places, and support of the new legislation.

Design: A before-after evaluation by comparing two cross-sectional studies the comparison of two transverse surveys.

Place: Primary Care, Delicias district (115,446 inhabitants) of Zaragoza city, including the Delicias Sur, Delicias Norte, Bombarda and Univérsitas basic health districts.