Brief report
Smoke Alarm and Battery Function 42 Months After Installation: A Randomized Trial

https://doi.org/10.1016/j.amepre.2010.05.018Get rights and content

Background

This randomized trial presents findings from the longest follow-up study of smoke alarm and battery function to date.

Purpose

The purpose of this study is to examine differences in long-term function of smoke alarm and battery combinations.

Methods

A total of 691 households in an ongoing cohort study were randomly allocated into smoke alarm groups of ionizing and photoelectric and battery groups of zinc and lithium. Smoke alarm function was measured in 633 (91.6%) households from January 2007 through February 2008, 42 months following original smoke alarm/battery installation. Data analyses were conducted in 2009.

Results

After 3.5 years, 81.9% of the 1898 smoke alarms were functional. Ionizing alarms with zinc batteries were the least likely to function (72.7%). In comparison, photoelectric alarms with lithium batteries were 2.9 times (95% CI=1.8, 4.5) more likely to function; ionizing alarms with lithium batteries were 2.0 times (95% CI=1.3, 3.1) more likely to function; and photoelectric alarms with zinc batteries were 1.7 times (95% CI=1.1, 2.5) more likely to function. Functionality was strongly tied to number of reports of nuisance alarms, which was higher for ionizing than photoelectric alarms.

Conclusions

Photoelectric smoke alarms and lithium batteries are the most likely to function long after smoke alarm installation, and may be worthwhile investments despite their increased cost.

Introduction

Smoke alarms are among the most effective interventions to reduce residential fire deaths.1, 2, 3, 4, 5, 6 Three RCTs7, 8, 9 have been conducted to identify the types of smoke alarms most likely to function up to 15 months after installation. All three studies compared the functionality of the two most common types of commercially available smoke alarms: ionization and photoelectric. Two of the studies also examined battery types and smoke alarm function. However, previous trials have not had sufficient follow-up periods to test the long-term function of battery types. This analysis follows the households from one of these randomized trials for 3.5 years (a previous analysis followed households for 1 year)—more than twice the length of previous studies9 to determine the alarm functionality.

Section snippets

Methods

Data were analyzed from an extended follow-up period for a previously published randomized trial,9 where details of the study methods and CONSORT diagram can be found. In summary, participants were recruited between July 2003 and June 2004 from an existing prospective cohort study.9, 10 Both the original cohort study and the smoke alarm trial were approved by the University of Iowa IRB. Participants were randomized using a sequential random number table into one of four smoke alarm/battery

Results

A total of 691 households were eligible for the 42-month follow-up visit. Excluded were 27 (3.9%) that could not be contacted after multiple efforts; 10 (1.4%) that were unoccupied; 6 (0.9%) whose owners no longer wished to participate; and 3 (0.4%) who had installed hard-wired alarms. Of 645 households visited, 12 (1.7%) were excluded because smoke alarm function data were not obtained or recorded. This analysis includes the remaining 633 households, which means 91.6% were involved in

Discussion

After 3.5 years, more than 90% of homes in this rural cohort had at least one functional smoke alarm, and more than 81% of alarms functioned. An earlier study8 found a similar proportion of functioning alarms, 84.2%, after 15 months. Another study,7 however, found that only 54.4% of homes had a functioning alarm, and 51.1% of study smoke alarms still functioned after 15 months. The only other study12 to examine long-term smoke alarm function in five states found that only 33% of the study's

Conclusion

The combination of photoelectric alarms with lithium batteries was the most likely smoke alarm/battery combination to function 3.5 years after installation, and the least likely combination to have nuisance alarms.

References (13)

  • J. Yang et al.

    Smoke alarms by type and battery life in rural households: a randomized controlled trial

    Am J Prev Med

    (2008)
  • S. Marshall et al.

    Fatal residential fires: who dies and who survives?

    JAMA

    (1998)
  • J.R. Hall

    The U.S. experience with smoke detectors: who has them? How well do they work? When don't they work?

    NFPA J

    (1994)
  • C.W. Runyan et al.

    Risk factors for fatal residential fires

    N Engl J Med

    (1992)
  • G.R. Istre et al.

    Smoke alarms and prevention of house-fire–related deaths and injuries

    West J Med

    (2000)
  • Smoke detectors essential for safety

    Consum Rep

    (1994)
There are more references available in the full text version of this article.

Cited by (0)

View full text