Over the years, as the connection between cigarette smoking and serious diseases has become indisputably clear, there has been an overall decline in the smoking rate within the general population. This change can be traced back to the first Surgeon General's Report in 1964, which officially reported cigarette smoking as the cause of cancer and other serious diseases. Subsequent acts to reduce the health hazard of smoking on society include the 1965 Federal Cigarette Labeling and Advertising Act requiring warning labels on cigarette packaging, and the prohibition of cigarette advertising on television and radio in 1969. Consequently, the smoking prevalence of adults (18 years and older) in the U.S. has declined over the years from 42.4% in 1965 to 24.1% in 1998. However, this rate seems to have reached a plateau in the 1990's, where it has hovered around the mid-20's percentage mark.
Of the astronauts who responded, 16.1% of them ever smoked, and 1.4% were still smoking, while the values for the comparison participants are 20.1% and 6.4%, respectively. For comparison purposes, smoking data among the U.S. general population were obtained from the National Health Interview Surveys (NHIS). The smoking prevalence among U.S. adults 25 years and older from 1995 to 1999 ranged between 24.5% and 23.4%. These numbers show that compared to the general population not only did a lower percentage of astronauts start smoking, but also that a much lower percentage of them continued to smoke. This behavior is expected because of their higher health awareness as compared to that of the general population. More surprising are the low prevalences of ever smoked and currently smoking comparison participants.
The smoking trend of LSAH participants can be estimated by breaking down the prevalence of participants who ever smoked into their selection year cohorts. This serves as an approximation of the LSAH participants' general attitude towards smoking within that time, and is compared against the smoking prevalence in the adult general population of the same period. The astronauts parallel the smoking trend of the general population, while comparison participants show a steeper decline compared to the other groups. Note that the measure of goodness of fit (R2) for the astronauts' and comparison participants' trendlines are 0.63 and 0.74, respectively. The trendline for the general population has an R2 of 0.97, very close to the maximum value of 1. A maximum goodness of fit is achieved when the line is a precise representation of the data points and their trend over time. The values obtained for the LSAH participants indicate that their trendlines are not as precise a representation of smoking prevalence over time as that of the general population. This is probably a function of the small sample sizes of the LSAH cohorts, which subjects the resulting prevalence to high variability.
In general the smoking prevalence of LSAH participants is much lower than that of the adult general population within the same time period. The lower smoking prevalence for astronauts as compared to the general population is expected, as by definition astronauts must be highly aware of activities affecting their health and fitness. However, the difference in smoking prevalence between the general population and the comparison participants is much greater than anticipated. When the data for LSAH participants ever smoked are broken down into cohorts, the results suggest that more comparison participants never started smoking at a higher rate as compared to the astronauts and general population.
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