Participants (N = 343) from an Oregon community completed surveys at baseli
ne, 3 months, and 12 months to assess personality, the perceived health ris
k of radon in combination with smoking, and changes in smoking behavior. Co
nscientiousness predicted instituting a more restrictive household smoking
rule (p < .01), and perceived risk predicted reduction in cigarettes smoked
per day for men (p < .001). Perceived risk predicted a reduction in the pr
oportion of cigarettes smoked in the home for those who had high (p < .05)
but not low or moderate levels of Conscientiousness, a dimension in one per
sonality model. The results demonstrate the importance of Conscientiousness
in the prediction of health behavior, particularly behavior that affects o
thers as well as oneself.