Comparison between Wet Bulb Globe Temperature (WBGT) App Prototype and WBGT Monitor to Assess Heat Stress Risk in Groundskeeping in an Eastern North Carolina University Setting

Abstract

Title: Comparison between WBGT App Prototype and WBGT Monitor to Assess Heat Stress Risk in Groundskeeping in an Eastern North Carolina University Setting

The wet bulb globe temperature (WBGT) index is the preferred environmental heat metric for occupational heat-related illness (HRI) prevention. However, WBGT data may not always be easily accessible for workplace heat stress evaluation. Thus, there is a need for well-designed WBGT-based tools that offer reliable, more accessible, and cheaper WBGT risk information for HRI prevention. A WBGT web app prototype was developed by ECU professors to calculate the current and forecasted WBGT, but it has not been tested for accuracy. The purpose of this study is to assess the reliability of the app prototype in providing accurate heat stress risk information for groundskeepers in eastern North Carolina by comparing the WBGT indices and risk levels from the app (WBGTapp) with those derived from heat stress monitor (WBGTins). Heat stress monitoring was conducted on campus using a heat stress monitor. The outdoor WBGT index was recorded for 81 days, and the hourly mean WBGT indices were compared to the ACGIH Threshold Limit Values and action limits for heat stress. Risk levels were assigned to WBGT indices based on workload. The WBGT app was used to record hourly WBGT indices and risk levels. Data analysis was conducted using t-tests, Pearson correlation tests, and cross-tabulation to assess the app's reliability in evaluating workplace heat stress risk. The study found that the hourly mean WBGTapp index was significantly higher (P<0.01) than the WBGTins index, but the difference between the overall average of the daily mean WBGTapp and the daily mean WBGTins was not statistically significant. There is a strong, positive correlation between the hourly mean WBGTapp and WBGTins indices (r=0.94, P<0.01), between the daily mean WBGTapp and WBGTins indices (r=0.97, P<0.01), and between the daily maximum WBGTapp and WBGTins indices (r=0.94, P<0.01). The hourly mean WBGTins indices ranged from 8.35 – 33.03 °C, while the hourly mean WBGTapp indices ranged from 6.11-37.78 °C. The app correctly identified 73-88% of minimal-risk conditions, depending on workload type, and was most reliable in identifying extreme-risk conditions at 97%, 95%, and 93% for light, moderate, and heavy workloads, demonstrating its capability to protect workers, especially for severe heat stress risk conditions. The WBGT app prototype is a promising tool for assessing heat stress risk, providing early warnings, and offering affordability and convenience for occupational heat stress prevention.