The study took place in New Zealand and involved all adult census respondents who had never smoked and were aged 45-74 years at the time of either the 1981 or 1996 population censuses.
Participants provided data on smoking status for all household members aged 15 and over and death rates were monitored for three years after the censuses.
Never smokers living in households with one or more current smokers were regarded as being exposed to secondhand smoke in the home. Those living in households with no current smokers were regarded as not exposed.
Among adults who had never smoked, the authors found a modest but consistent association between exposure to secondhand smoke in the home and death. Adults who had never smoked and who lived with smokers had about a 15% higher risk of death than those living in a smoke-free household, even after taking into account differences in age, ethnicity, marital status, and socioeconomic position.
This finding is consistent with previous studies in this area, but is more precisely measured due to being based on a large study, say the authors.
Despite some limitations, the results from this study add to the weight of evidence of harm caused by passive smoking and support steps to reduce exposure to other people's smoke in the home and in other settings, they conclude.