March 15, 2011 -- The stereotypical pack-a-day smoker is no longer the norm, according to a new study that shows the number of heavy smokers has declined substantially in the U.S.
Researchers say that in 1965, a majority of smokers in the U.S. smoked at least one pack per day. But since the first surgeon general's report on smoking and health was released in 1964, there has been a major decline in not only the prevalence of smoking, but also the intensity.
In the study, researchers analyzed smoking intensity patterns from two large national health surveys involving more than 1.6 million Americans and 139,176 residents of California.
Researchers conducted separate analyses of smoking patterns in California because the state has consistently led the U.S. in initiating public policies to reduce cigarette smoking since the surgeon general's report on smoking was released.
The results showed 23.2% of adults in California and 22.9% of adults in the rest of the U.S. were classified as heavy smokers in 1965.
By 2007, this prevalence dropped to 2.6% of adults in California and 7.2% of adults in the remaining states.
"This decline in high-intensity smoking was not accompanied by a compensatory increase in the prevalence of less-intense smoking," write researcher John P. Pierce, PhD, of the University of California, San Diego and colleagues in the Journal of the American Medical Association.
Instead, researchers say the overall pattern of smoking has changed across different generations. They found the prevalence of moderate-intensity smoking of 10 or more cigarettes per day also declined.
In 1965 11.1% of adults in California and 10.5% in the remaining states were classified as moderate-intensity smokers.
By 2007, the prevalence fell to 3.4% in California and 5.4% in the remaining states.
"As expected, the large decline in the prevalence of pack-a-day smoking has been reflected in declines in lung cancer," write the researchers. "Lung cancer death rates peaked in California in 1987 at 109 per 100,000 and declined continuously to 77 per 100,000 in 2007. In the remaining United States, lung cancer deaths peaked in 1993 at 117 per 100,000 and declined to 102 per 100,000 by 2007."
Researchers say further studies on changes in smoking patterns should look at the relative importance of changes in the age at which smokers began their habit, when they quit, and the relative importance of cutting back on the number of cigarettes smoked per day on the health consequences of smoking.