To the Editor We read with interest the article by Newbury et al¹ on the association of air pollution exposure and psychotic experiences during adolescence. We agree with the authors that the strong association between exposure to nitrogen oxides and psychotic experiences implicates road traffic. We hypothesize that exposure to the extensively studied and formerly ubiquitous developmental neurotoxin, tetraethyl lead, may be causally linked to psychotic disorders and may confound the observed association between nitrogen oxides and psychotic experiences. Leaded gasoline was not completely banned in the United Kingdom until 1999. Prior to that, all individuals, including children and pregnant women, living close to major roads and in larger cities with substantial automobile traffic had considerable exposure to tetraethyl lead from car exhaust.