Everyone knows that smoking is bad for you, right? Not according to a new Duke Health study. 

Published in the journal Drug and Alcohol Dependence, the research found that people's perceptions of smoking risks may be declining, even though three out of four Americans agree that smoking can cause health problems. 

“Risk perceptions are related to people’s decision to engage in a certain behavior,” said Lauren Pacek, assistant professor in psychiatry and behavioral sciences and lead author of the study. “It’s pretty critical to monitor not only tobacco use but also keep an eye on people's perception of tobacco.”

According to the study, the number of Americans who believe that smoking a pack of cigarettes or more a day poses a health risk decreased by one percent from 2006 to 2015. Although this may not seem like much, the figure represents more than three million Americans. Women’s beliefs on the risks dropped more quickly than men’s. 

“While women do perceive smoking as more harmful than men, the rates that they do have been decreasing compared to men,” said Joe McClernon, professor in psychiatry and behavioral sciences and study co-author. 

Pacek noted that the research team is uncertain about the reason behind this. 

“We’re still sort of trying to work through and figure it out,” she said. “The findings overall are a little puzzling, but especially for women they’re puzzling.”

The study also found that older teenagers and adults more often saw smoking as a health risk than kids aged 12 to 17. In addition, daily smokers were less likely to view smoking as dangerous to their health than former smokers or non-smokers. 

The number of smokers in the United States is still decreasing, from 20.8 percent in 2006 to 15.1 percent in 2015. Yet the decrease in risk perception may represent a slowing of progress in publicizing the dangers of smoking. 

This is especially concerning given that smoking products have not become safer in the past 15 years and as many as 400,000 Americans die from tobacco-related diseases each year. 

The study used responses from the National Survey on Drug Use and Health which included more than 559,000 people over age 12. It asked the question, “How much do people risk harming themselves physically and in other ways when they smoke one or more packs of cigarettes per day?” 

Participants could respond with “no risk,” “slight risk,” “moderate risk” or “great risk.”

Pacek noted that the reason behind the decline in risk perception could be caused by message fatigue. 

“From a public health standpoint, we’ve done a pretty good job conveying the message that smoking is bad,” she said. “It’s possible people have heard the message so many times that it no longer has an impact.”

In addition, since the prevalence of smoking in the United States has gone down, there have been fewer people with smoking-related diseases. This means that people are less likely to know someone who has personally suffered from smoking’s effects, leading them to take the danger less seriously. 

Pacek explained that future studies should continue looking at the data on risk perception. Her team hopes in the future to examine people’s beliefs about other tobacco products like electronic cigarettes.

They also plan to look for other sources of data and ask similar questions to see if they can replicate the findings, McClernon said. 

He noted that the study is helpful in understanding why people smoke and how it’s about more than just an addiction to nicotine. 

“There are other factors like beliefs and attitudes that also influence smoking behavior,” McClernon said. “So it’s worth monitoring how those beliefs and attitudes change over time.” 

This research also has implications for developing new ways to reach people who no longer think smoking is that bad. 

“We’re hoping that people who are policy experts and people who do have expertise in the development of educational and messaging campaigns will take notice of [this study] and run with it,” Pacek said.