Kaplan GG, Hubbard J, Korzenik J et al. Am J Gastroenterol 2010;105:2412–9.
These authors conducted a case–control study to investigate whether air pollution levels are associated with the incidence of IBD. Overall, no association between the level of air pollution and IBD was identified; however, exposure to nitrogen dioxide and sulfur dioxide appeared to increase the risk of early-onset Crohn’s disease and ulcerative colitis, respectively.
IBD emerged during the late 19th and early 20th centuries in industrialized countries. The purpose of this study was to evaluate the possible association between the exposure to air pollutants and the development of IBD. A case–control study was conducted, with incident cases of IBD identified and matched with control subjects for age and sex. During the period from 1st July 2005 to 31st October 2008, 367 patients were newly diagnosed with Crohn’s disease and 591 with ulcerative colitis (UC). Conditional logistic regression analysis was used to determine if areas with higher concentration of pollutants (determined as quintiles of concentration) were associated with a greater incidence of IBD diagnosis after adjusting for smoking, socioeconomic status, appendectomy, and prescription of nonsteroidal anti-inflammatory drugs.