The EMECAM project: a multicentre study on air pollution and mortality in Spain: combined results for particulates and for sulfur dioxide.
Ballester F, Sáez M, Pérez-Hoyos S, Iñíguez C, Gandarillas A, Tobías A, Bellido J, Taracido M, Arribas F, Daponte A, et al. Occup Environ Med. 2002 May; 59(5):300-8.