Cross-sectional analysis of site- and ambient temperature–related variability in noncontact infrared thermometry among healthy Black African adults

Abstract

Objectives Noncontact infrared thermometers are widely used for rapid screening, particularly during infectious disease emergencies. Although noncontact use is time-efficient and helps maintain a safe distance, their readings may be influenced by the anatomical measurement site and ambient temperature, and evidence from Black African populations remains limited. This study examined the variability and agreement of noncontact infrared thermometer–derived surface temperature readings obtained from different anatomical sites under two controlled ambient temperature conditions in healthy Black African adults. Methods In this cross-sectional, repeated measures study, noncontact infrared thermometer–derived temperatures were obtained from 216 healthy adults using sites including the forehead, neck, temple, and wrist (in that order) in an environmental chamber maintained at 18°C and subsequently at 28°C. Differences across anatomical sites and ambient conditions were assessed using the Wilcoxon signed-rank and the Friedman tests with Bonferroni correction. Bland–Altman analysis and Cohen's kappa were used to assess agreement between readings and temperature classification obtained under the two ambient conditions. Results Increasing the ambient temperature from 18°C to 28°C significantly increased forehead, neck, and temple readings (all p < 0.001), whereas wrist readings did not change significantly. Temperature readings differed significantly among anatomical sites at both ambient conditions ( p < 0.001). Most neck (94.9%) and forehead (74.5%) readings were classified within the predefined normal range, whereas wrist and temple readings were frequently classified below this range. Agreement in temperature classification between ambient conditions was fair for the neck (κ = 0.42, p < 0.001) and lower for the other sites. Conclusion Noncontact infrared thermometer–derived surface temperature readings vary substantially according to anatomical site and ambient temperature in healthy Black African adults. The findings confirm the relevance of previously identified site- and environment-related measurement variability in this underrepresented population and support the use of standardized, site-specific noncontact infrared thermometer measurement protocols.