How long do smoke alarms function? A cross-sectional follow-up survey of a smoke alarm installation programme.

Objective: To assess the functionality of lithium-powered smoke alarms that had been installed through a community-based programme called Operation Installation (OI).

Methods: A random sample was chosen of homes that had received smoke alarms through OI, 2, 4, 6, 8 and 10 years previously. Sampled homes were visited, and information collected included functional status of smoke alarms. For homes in the 6-, 8- and 10-year sample, smoke alarms were removed and tested for battery and alarm function.

Results: 800 homes were included in the survey results; 1884 smoke alarms had been installed through OI. The proportion of homes that had at least one functioning OI smoke alarm ranged from 91.8% for year 2 sample to 19.8% for year 10. Of the originally installed smoke alarms in year 10 sample, 45.5% had been removed and 59% (64/108) of those that were still installed were not functioning. Multivariate analysis showed that the presence of at least one working alarm in the home was associated positively with the number of smoke alarms that were originally installed and whether the original occupant was still living in the home, and negatively with the length of time since the smoke alarm was installed, and whether there was a smoker in the home. Testing of the smoke alarms revealed that most non-functioning alarms had missing or dead batteries.

Conclusions: Less than a quarter of the originally installed smoke alarms were still present and functioning by year 10. These findings have important implications for smoke alarm installation programmes.