Smoky homes: a review of the exposure and effects of secondhand smoke in New Zealand homes

Aims To review the evidence of exposure to secondhand smoke (SHS) in New Zealand homes and its effects on health. Methods A search for relevant literature was made in April-May 2004, using Medline and other databases, and via inquiries to official and other agencies. Data on the types of households with smoking members were obtained by an analysis of 1996 Census data. Results National survey data indicate that at least 18% of all New Zealanders and 30% of Maori are exposed to SHS in the home. Surveys of high school students indicate home SHS exposure levels of 30% or more. The exposure appears to have decreased during 1996-2003 for Maori and the general population (p< 0.001 for trend for both), with low-income households more likely to be exposed than others. There is an absence of exposure data for many specific population groups including pregnant women and infants. New Zealand evidence from two large cohort studies indicates an increased risk of death of at least 15% for never smokers, aged 45-74, if they live in a household with smokers. Over 250 deaths per year are estimated to be attributable to SHS exposure in New Zealand homes; over double the mortality from SHS exposure at work. Conclusions Improved information on SHS exposure in the New Zealand setting is needed. The levels of home SHS exposure and estimated mortality burden justify a substantial Government and health-agency investment to reduce this exposure, particularly for children, Maori, and those in low-income households.