Survey results indicate that smoking and alcohol and marijuana use increased among residents of Manhattan during the 5-8 weeks after the terrorist attacks on the World Trade Centre which took place on September 11,2001. Almost one third of the nearly 1,000 persons interviewed reported an increased use of alcohol, marijuana, or cigarettes following the September 11th attacks. The largest increase was in alcohol use. About one fourth of the respondents said they were drinking more alcohol in the weeks after September 11 about 10% re-ported an increase in smoking, and 3.2% said they had increased their use of marijuana. The investigators found survey participants by randomly dialing New York City phone numbers and screened potential respondents for Manhattan residents living in areas close to the World Trade Centre. Interviews were conducted with 988 individuals between October 16 and November 15,2001. Participants were asked about their cigarette smoking, alcohol drinking, and marijuana use habits before and after September 11. During the week prior to September 11,2001, 22.6% of the participants reported smoking , cigarettes 59.1% drinking alcohol, and 4.4% using marijuana. After September 11th, 23.4% reported smoking cigarettes, 64.4% drinking alcohol, and 5.7% smoking marijuana. Among those who smoked, almost 10% reported smoking at least an extra pack of cigarettes a week and among those who drank alcohol, more than 20% reported imbibing at least one extra drink a day. The researchers found that people who reported an increase in substance abuse were more likely to suffer from post-traumatic stress disorder (PTSD) and from depression. People who reported an increase in cigarette smoking or marijuana use were also more likely to have both PTSD and depression, while those who reported an increase in alcohol use were more likely to have depression only. Persons who were living closer to the World Trade Centre were more likely to increase their cigarette smoking, but other factors such as being displaced from home, losing possessions during the attacks, or being involved in the rescue efforts were not consistently associated with increased substance use. Symptoms of panic attack were associated with an increase in the use of all substances. Increase in substance abuse did not differ significantly between men and women or among racial or ethnic groups. Demographic factors such as age, marital status, and income seemed to play a more critical role in determining if the events of September 11th led to an increase in substance use. The survey results suggest that the largest increase in substance use was ______ .