Background:
Although smoke-free public places are an important population-wide intervention to protect non-smokers from the harm of smoking and to encourage smokers to quit, others suggest it may increase smoking in homes. This study therefore sought to determine exposure to secondhand smoke (SHS) at home and in public places before and after 2009 when an amendment to legislation that introduced significant increase in fines came into effect. The study also sought to explore the association between SHS exposure and smokers' intention to quit.

Methods:
This cross-sectional study involved three nationally representative samples of South African adults aged ≥16 years who participated in the 2007 (n=2,907), 2010 (n=3,112), 2016 (=3,063) South African Social Attitude Survey. Information obtained using interviewer-administered questionnaire included socio-demographic characteristics and self-reported exposure to tobacco smoking at home and public places (work, bars/clubs, and restaurants). The three datasets were merged (Pooled N = 9,082). Data analysis included chi-square statistics and multiple logistic regression analysis.

Results:
During 2007-2016, the proportion of South Africans who reported exposure to SHS at home on any one day increased from 31.9% in 2007 to 36.6% in 2016 (p=0.637), while exposure on any one day at any one of the various public places decreased significantly from 71.9% to 54.4% (p< 0.001), albeit significantly only between 2010 and 2016. Compared to smokers exposed to others' smoking, those not exposed were more likely to report planning to quit (OR=1.73; 95%CI=1.07-2.79). However, after controlling for the number of cigarettes smoked daily, exposure to others' smoking in public was no longer significant, thus suggesting that the decreasing number of cigarettes smoked daily was the mediator of the effect of restricting public smoking.

Conclusions:
While our findings suggest that the most recent legislative amendment related to public smoking seem to have reduced SHS exposure, further restrictions, which may motivate quitting, are still needed.