Graduation Year
2023
Document Type
Thesis
Degree
M.S.P.H.
Degree Name
MS in Public Health (M.S.P.H.)
Degree Granting Department
Public Health
Major Professor
Thomas E. Bernard, Ph.D.
Committee Member
René R. Salazar, Ph.D.
Committee Member
Steven Mlynarek, Ph.D.
Keywords
heat assessment, heat stress, humidity, wind speed
Abstract
The Wet bulb globe temperature (WBGT) is a common method to evaluate environmental factors that contribute to occupational heat stress. The Heat Index (HI) is readily available as an alternative to exposure methods. They both assess the most important contributors that are air temperature and humidity. WBGT also includes radiant heat and air motion. To account for radiant heat and/or air motion, some investigators have suggested adjustments to HI. The purpose of this study is to explore two methods to estimate the usefulness of WBGT from HI.
WBGT data were collected in a variety of locations that included direct sun v. shade, three levels of cloud cover, and green v pavement areas. There were 128 observations. HI data were collected using the NIOSH/OSHA app, the ambient data at Tampa International Airport, and at a nearby Weather Underground location near the measurement site. The methods of Bernard & Iheanacho and of Irvin were used to estimate WBGT from HI.
The results were evaluated by finding the ∆WBGT as the difference of estimated minus measured WBGT. The mean and standard deviation of ∆WBGT was computed for each method and a Bland-Altman plot was made. The slope of the line in the Bland-Altman plot was also determined and whether it was significantly different from zero. The accuracy was assessed by the mean ∆WBGT and the precision by the standard deviation. The accuracy ranged from -7 to +2.4, with only three combinations of location and estimation method within ± 1.0 °C. For all methods and locations, the standard deviation ranged from 3.9 to 5.5 °C, meaning there was unacceptable precision.
In conclusion, neither method of estimating WBGT from HI are both adequately accurate or precise.
Scholar Commons Citation
Pofanl, Stephi, "Evaluation of Two Methods to Estimate Wet Bulb Globe Temperature from Heat Index" (2023). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/9994
