Vicarious exposure to terrorist attacks and substance use: results from an urban household survey.

This study investigated the impact of the 9/11 attacks on substance use in Chicago, Illinois. The study design was a cross-sectional, audio-computer-assisted self-interview survey conducted in 2001 and 2002. Biological samples were also collected for toxicological analyses. Using a multistage area probability design, residents between the ages of 18 and 40 years were randomly selected. Compared to pre-9/11 interviewees, post-9/11 interviewees showed significantly less self-reported marijuana use, marijuana use per test results, and cocaine use per test results. Law enforcement and social-structural explanations for the findings are discussed.