Table 1 Characteristics of respondents, households, and houses reported at baseline interview, by randomized study alarm type
CharacteristicIonization (n = 366*) (%)Photoelectric (n = 384*) (%)
Age (years)
    Asian/Pacific Islander10.711.4
    Native American0.81.3
    <High school5.28.7
    High school/GED21.225.2
    Vocational/technical/some college30.030.5
Number of residents
⩾1 resident aged
    ⩽4 years16.215.7
    ⩽14 years33.835.3
    ⩾65 years29.025.5
⩾1 resident smokes†24.425.0
⩾1 resident drinks alcohol‡25.925.3
Single family residence98.9100.0
Year built
Ever structurally remodeled51.052.7
Year built or last remodeled
Number of floors
Years in current house
Kitchen stove type§
Frequency of kitchen stove use
    Multiple days per week27.224.5
    Rarely/occasionally/weekends only8.39.0
Main heat source
    Natural gas54.449.2
Electric main or secondary heat source33.640.6
Natural gas main or secondary heat source53.549.3
Oil main or secondary heat source19.018.5
Open-element space heater19.520.8
Wood fireplace37.547.1
Gas fireplace insert4.91.8
Wood or pellet stove20.820.8
Frequency of fireplace or stove use¶
  • *Among households that were eligible for analyses (had study alarm installed, were home owners, and received a zinc battery in the study alarm).

  • †Defined as smoking a pack (20 cigarettes) or more per week.

  • ‡Defined as drinking 5 or more alcoholic beverages on occasion.

  • §Not mutually exclusive since some kitchens have two stoves, so percentages may add to >100%.

  • ¶Based on the single most frequently used fireplace or stove per household.