Prevalence of heavy smoking in California and the United States, 1965-2007

Context: The intensity of smoking, not just prevalence, is associated with future health consequences.

Objective: To estimate smoking intensity patterns over time and by age within birth cohorts for California and the remaining United States.

Design, Setting, and Participants: Two large population-based surveys with state estimates: National Health Interview Surveys, 1965-1994; and Current Population Survey Tobacco Supplements, 1992-2007. There were 139 176 total respondents for California and 1 662 353 for the remaining United States.

Main Outcome: Measure Number of cigarettes smoked per day (CPD), high-intensity smokers (≥20 CPD); moderate-intensity smokers (10-19 CPD); low-intensity smokers (0-9 CPD).

Results: In 1965, 23.2% of adults in California (95% confidence interval [CI], 19.6%-26.8%) and 22.9% of adults in the remaining United States (95% CI, 22.1%-23.6%) were high-intensity smokers, representing 56% of all smokers. By 2007, this prevalence was 2.6% (95% CI, 0.0%-5.6%) or 23% of smokers in California and 7.2% (95% CI, 6.4%-8.0%) or 40% of smokers in the remaining United States. Among individuals (US residents excluding California) born between 1920-1929, the prevalence of moderate/high-intensity smoking (≥10 CPD) was 40.5% (95% CI, 38.3%-42.7%) in 1965. Moderate/high-intensity smoking declined across successive birth cohorts, and for the 1970-1979 birth cohort, the highest rate of moderate/high-intensity smoking was 9.7% (95% CI, 7.7%-11.7%) in California and 18.3% (95% CI, 16.4%-20.2%) in the remaining United States. There was a marked decline in moderate/high-intensity smoking at older ages in all cohorts, but this was greater in California. By age 35 years, the prevalence of moderate/high-intensity smoking in the 1970-1979 birth cohort was 4.6% (95% CI, 3.0%-6.1%) in California and 13.5% (95% CI, 11.8%-15.1%) in the remaining United States.

Conclusions: Between 1965 and 2007, the prevalence of high-intensity smoking decreased greatly in the United States. The greater decline in high-intensity smoking prevalence in California was related to reduced smoking initiation and a probable increase in smoking cessation.

Throughout much of the early history of cigarette smoking in the United States, modal consumption was 1 pack of cigarettes each day.1 Since the first surgeon general's report on smoking and health (1964),2 there has been a major decline in smoking prevalence from 40.4% in 19651 to 20.8% in 2006.3 During this period, California consistently led the United States in using public policies to reduce cigarette smoking, and there were faster declines in smoking prevalence in California compared with the remaining United States (0.74% per year vs 0.53% per year, respectively) as well as in lung cancer rates (2007 rates: California, 77.1/100 000 vs the remaining United States, 101.7/100 000).4 Lung cancer risk is related to both the duration of smoking and the intensity of consumption,5,6 and population changes in initiation, cessation, and amount smoked are reflected in age-specific smoking intensity patterns.

This article reports trends in smoking intensity for both California and the remaining United States using population-based surveys conducted from 1965-2007. This study considers how age-related patterns in higher-intensity smoking have changed across birth cohorts and draws inferences on the role of smoking initiation and cessation.