Dr. Michael F. Pesko, an instructor in Weill Cornell Medical College's Department of Public Health in New York, said an examination of data from the Behavioral Risk Factor Surveillance System and found 950,000 to 1.3 million adult former smokers resumed smoking, representing a 2.3 percent increase nationwide.
There was no increase in the months and years following the 1995 Oklahoma City bombing, the study found.
"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," Pesko, the study author, said in a statement. "It sheds light on a hidden cost of terrorism."
The Behavioral Risk Factor Surveillance System tracked annual rates of risky personal behavior across the nation after the Sept.11, 2001, attacks and the Oklahoma City bombing.
Health departments in every state conduct monthly phone surveys of residents, asking about seat belt use, smoking and drinking habits, the last time they visited a doctor or dentist, etc., Pesko said. The Centers for Disease Control and Prevention in Atlanta combines the data and releases an annual, nationally representative report. Since the same questions are asked yearly, responses can be compared over time, Pesko said.
Pesko compared 1.6 million responses to the nationally representative questionnaire, and extrapolated that from the fourth quarter of 2001 through 2003, when the study ended.
The study was published in the journal Contemporary Economic Policy.