title: Sensor drift and predicted calibration intervals of handheld temperature and relative humidity meters under residential field-use conditions.
abstract: Handheld temperature and relative humidity (T/RH) meters are commonly used in residential indoor air surveys. Although popular, T/RH meters are prone to sensor drift and consequent loss of accuracy, and thus instrument manufacturers often recommend annual calibration and adjustment. Field-use conditions, however, have been shown to accelerate electronic sensor drift in outdoor applications, resulting in out-of-tolerance measurements in less than one year. In the study described in this article, sensor drift was evaluated under residential field use for 30 handheld T/RH meters to predict needed calibration intervals based on hierarchical linear modeling. Instruments were used in 43 home visits over a 93-day period and were calibrated (without adjustment) 49 times over the study period with a laboratory standard. Analysis of covariance showed significant drift among temperature sensors for all three instrument types (p < .0001) and among humidity sensors in two instruments. The authors' study suggests calibration frequency should be based on instrument performance under specific sampling conditions rather than on predetermined time intervals.
authors.affiliation: Department of Health Sciences, Brigham Young University.
authors.lastname: Johnston James D
authors.forename: Brianna M
authors.initials: BM
authors.lastname: Magnusson
authors.forename: Dennis
authors.initials: D
authors.lastname: Eggett
authors.forename: Kyle
authors.initials: K
authors.lastname: Mumford
authors.forename: Scott C
authors.initials: SC
authors.lastname: Collingwood
authors.forename: Scott A
authors.initials: SA
authors.lastname: Bernhardt
mesh_terms: D000388:Air / Q000032:analysis*; D002138:Calibration; D004784:Environmental Monitoring / Q000295:instrumentation*; D006798:Housing; D006813:Humidity; D016014:Linear Models; D015203:Reproducibility of Results; D013696:Temperature; D013997:Time Factors