Future Work

Future work should investigate the following lingering questions. First, it is assumed that the variability of WBGT values across space is higher than the variability of air temperature and Heat Index. This assumption is based off the fact that WBGT incorporates the effects of wind speed and solar radiation which can vary greatly over small spatial and temporal scales. Rapid changes in cloud cover, and thus changes in solar radiation, has been previously identified as a challenge for directly measuring WBGT (Kopec, 1977; Lundgren et al., 2014), thus the effect on estimating WBGT would be assumed to be even larger. Quantifying the decay in accuracy of estimated WBGT at increasing distances from the weather stations at which it is estimated would greatly inform this concern with the high spatial variability of WBGT.

Second, it may be possible to improve the estimation of solar radiation from cloud cover data at ASOS and AWOS stations beyond the methodology that was developed here, which could improve the accuracy of the estimated WBGT. In this research, the cloud cover percentage

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reported at each level were all averaged to produce a singular cloud cover percentage per observation that was then used to modify maximum possible solar radiation. One potential alternative is to calculate a weighted average of the cloud cover percentage, with weights dependent upon the cloud cover height, since clouds at varying levels do not block solar radiation equally, as assumed here.

Third, further stratification of the health outcome data based on age, race, and other demographic and socioeconomic factors could better delineate the overall ill health burdens due to heat, the regional differences therein, as well as the ability of specific heat stress metrics to more robustly define these heat-health relationships. Since WBGT is commonly used in

occupational and athletic settings, analyzing the relationships of WBGT with injuries or deaths in these settings could elucidate the utility of existing WBGT flag categories and corresponding heat safety recommendations (Table 2).

Lastly, the findings of this research that urban areas show a higher heat-health burden contrasts with previous research on the impact of extreme heat on heat-related morbidity in North Carolina (Kovach et al., 2015; Sugg et al., 2016). An important distinction is that the research presented here is focused on mortality while prior research focused on morbidity that was specifically coded as heat-related. While this distinction is a possible explanation for the contrasting results, this contrast supports the need of future research to identify the relationships between WBGT and morbidity, particularly HRI, to further assess the ability of WBGT to predict heat-related health outcomes relative to other metrics

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