About 1 million American people who had quitted smoking started to puff again in the wake of the Sept. 11 attack in 2001, a study from Weill Cornell Medical College public health showed. The study, published by the journal Contemporary Economic Policy on Thursday, is the first to look at the net costs to society of terrorism-induced smoking in the United States after the 9/11 attack and the bombing in Oklahoma City. \"This study provides the first unbiased estimate of the effect of stress on smoking, and the finding that there was such a big increase in smoking nationwide, seemingly due to one event, is extraordinary, and surprising,\" says Pesko. \"It sheds light on a hidden cost of terrorism.\" \"This helps us better understand what the real costs of such disasters are in human and economic tolls, and it suggests ways that such future stressful reactions that result in excess smoking might be avoided,\" says the study\'s author Michael F. Pesko. While the Oklahoma City bombing did not affect smoking rates in the U.S., Pesko suggests that 9/11 caused a significant 2.3 percent increase of smoking nationwide. The increase started after 9/11 and continued through the end of 2003, when analysis of the data ended, he says. Self-reported stress was also found to especially increase in communities with a higher concentration of active-duty and reserve members of the military, and among higher-educated groups. The increase in stress following 9/11 was found to account for all of the increase in smoking. Pesko has long been interested in the relationship between stress and substance abuse. \"There is a consensus in the research community that stress is a very large motivator for individuals to use substances, but this has not really been studied very thoroughly,\" he says. He estimates the cost to government of 9/11-induced smoking at 530 million U.S. dollars to 830 million dollars, and potentially higher if the smoking continued beyond 2003. These figures represent changes in the use of Medicare and Medicaid, productivity losses associated to illness from smoking, and decreased tax revenue linked to lost work. The figure also takes into account increased tax revenue from cigarette purchases. The study findings suggest a potential public health response to future stress-inducing events, says Pesko. One possibility would be programs that offer free nicotine replacement therapy soon after the events, he says. \"Another strategy would be to alert health professionals to do more substance abuse screening during regular medical appointments following terrorist attacks, or any such event that is likely to stress the nation,\" he says.