Graduation Year

2022

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., CIH

Committee Member

Steven Mlynarek, Ph.D., CIH.

Committee Member

Rene Salazar, Ph.D., CIH

Keywords

air speed, heat stress, occupational exposure limit, solar radiation, WBGT

Abstract

Wet bulb globe temperature (WBGT) is a common metric to represent the environmental conditions in the assessment of heat stress. Because WBGT requires some technical expertise and sufficiently accurate equipment, there is interest in using heat index (HI) as a substitute index for the environment. Because the underlying science for understanding heat stress exposures does not exist for HI, it is necessary to crosswalk between HI and a data-driven exposure method. Expanding upon previous research, the focus of this study is the exploration of the interrelationships between WBGT and HI. The simulated weather data of Morris et. al. (2019) served as the basis for this study. To crosswalk HI to WBGT a 2nd order polynomial regression was used to generate a base model to which adjustment factors were applied corresponding to a range of applied dew point temperatures (Tdp °F), qualitative assessments of sun exposure (shade, cloudy, full sun), and air speed (Beaufort wind force observations). Adding the WBGT adjustment factors to the WBGTref equation, the mean change in WBGT (°C) from the base data to the result is near 0 with a range of -1.2 to 1.4 °C. The same process was followed to crosswalk WBGT to HI. Adding the HI adjustment factors to the HIref equation, the mean change in HI (°F) from the base data to the result is near 0 with a range of -8.4 to 8.2 °F. Testing the models’ sensitivity and specificity using in situ data will need to be performed to determine the efficacy of the models before they are used in heat stress risk assessment estimates.

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