Prevalence of working smoke alarms in local authority inner city housing: randomised controlled trial.

OBJECTIVES

To identify which type of smoke alarm is most likely to remain working in local authority inner city housing, and to identify an alarm tolerated in households with smokers.

DESIGN

Randomised controlled trial.

SETTING

Two local authority housing estates in inner London.

PARTICIPANTS

2145 households.

INTERVENTION

Installation of one of five types of smoke alarm (ionisation sensor with a zinc battery; ionisation sensor with a zinc battery and pause button; ionisation sensor with a lithium battery and pause button; optical sensor with a lithium battery; or optical sensor with a zinc battery).

MAIN OUTCOME MEASURE

Percentage of homes with any working alarm and percentage in which the alarm installed for this study was working after 15 months.

RESULTS

54.4% (1166/2145) of all households and 45.9% (465/1012) of households occupied by smokers had a working smoke alarm. Ionisation sensor, lithium battery, and there being a smoker in the household were independently associated with whether an alarm was working (adjusted odds ratios 2.24 (95% confidence interval 1.75 to 2.87), 2.20 (1.77 to 2.75), and 0.62 (0.52 to 0.74)). The most common reasons for non-function were missing battery (19%), missing alarm (17%), and battery disconnected (4%).

CONCLUSIONS

Nearly half of the alarms installed were not working when tested 15 months later. Type of alarm and power source are important determinants of whether a household had a working alarm.