title: Smoke alarm and battery function 42 months after installation: a randomized trial.
abstract: BACKGROUND
  This randomized trial presents findings from the longest follow-up study of smoke alarm and battery function to date.
  
  
  OBJECTIVE
  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.
authors.affiliation: Injury Prevention Research Center, University of Iowa, Iowa City, Iowa 52241, USA. corinne-peek-asa@uiowa.edu
authors.forename: Corinne
authors.initials: C
authors.lastname: Peek-Asa
authors.forename: Jingzhen
authors.initials: J
authors.lastname: Yang
authors.forename: Cara
authors.initials: C
authors.lastname: Hamann
authors.forename: Michael P
authors.initials: MP
authors.lastname: Jones
authors.forename: Tracy
authors.initials: T
authors.lastname: Young
authors.forename: Craig
authors.initials: C
authors.lastname: Zwerling
mesh_terms: D004867:Equipment Design; D005390:Fires / Q000517:prevention & control*; D005500:Follow-Up Studies; D006794:Household Articles / Q000295:instrumentation*; D006801:Humans; D008094:Lithium / Q000737:chemistry; D012424:Rural Population; D012449:Safety; D013997:Time Factors; D015032:Zinc / Q000737:chemistry
chemical_list: D008094:Lithium; D015032:Zinc