Incorporating occupational risk in heat stress vulnerability mapping.

Author:Crider, Kyle G.
Position:ADVANCEMENT OF THE SCIENCE
 
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Introduction

Heat stress is a serious health threat during the summertime for a large portion of the U.S. population, particularly during physical exertion. According to the Centers for Disease Control and Prevention (CDC), from 1979 to 2003 heat killed 8,015 Americans--more than hurricanes, lightning, tornadoes, floods, and earthquakes combined (CDC, 2009). Recent government statistics on heat-related fatalities indicate, "Between 1999 and 2003, a total of 3,442 deaths resulting from exposure to extreme heat were reported (annual mean: 688) and males accounted for 66% of those deaths (CDC, 2006a)." In 2011, 206 people died as a result of extreme heat, up from 138 fatalities in 2010 (National Oceanic and Atmospheric Administration [NOAA], 2012). The 10-year average for heat-related fatalities is 119 (NOAA, 2012).

In 2012 the Intergovernmental Panel on Climate Change (IPCC) released a special report on extreme events, concluding that increases in the frequency and magnitude of warm daily temperature extremes and decreases in cold extremes will occur in the 21st century at the global scale with 99%-100% probability (IPCC, 2012). The report also states that daily temperature extremes will increase this century, with 90%-100% probability that heat waves will increase in length, frequency, or intensity over most land areas. Observations since 1950 document changes in daily temperature extremes and heat waves (IPCC, 2012) and a recent analysis of extreme heat events in the U.S. between 1979 and 2011 suggests the number of heat wave days has been increasing in the southeast (Smith, Zaitchik, & Gohlke, 2012).

Anderson (2011) estimated that limiting the global mean temperature to 2[degrees]C of warming will still result in current historical temperature extremes becoming the norm for 70%-80% of the Earth's surface. Hyatt and co-authors (2010) utilized published formulas for the Wet Bulb Globe Temperature (WBGT) in combination with global gridded climate data and concluded that estimated future increases of WBGT may create extreme heat exposure situations in large areas of the world.

Although global and national estimates of health effects due to climate change have been summarized, further studies are required to develop a better understanding of health risks across divergent geographical locations (Zhang, Bi, & Hiller, 2007). Public health researchers and practitioners are playing a lead role in this endeavor to develop estimates of interaction between exposure and susceptibility to health effects in identifying the most appropriate adaptation measures (Luber & Hess, 2007). For example, the elderly are thought to be particularly susceptible to heat stress, and mapping of the proportion of elderly has been used in adaptation planning (Minnesota Department of Health, 2013). In contrast, occupational risk factors have received limited attention in public health adaptation planning.

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Alabama's high humidity and temperature extremes can lead to heat-related illnesses (HRI) and deaths (Alabama Department of Public Health [ADPH], 2012a). A study of temperature-related deaths in Alabama by Taylor and McGwin (2000) found that mortality rates for hyperthermia were higher in Alabama than nationally. The authors stated that rates among males were higher than those of females, with the highest rates found among African-American males. The cause of the higher rates among African-American males is not known, but the finding was consistent with nationwide studies (CDC, 2000). Risk factors include low socioeconomic status, alcohol consumption, certain drugs, underlying chronic disease, previous heat stroke, and physical exertion (Taylor & McGwin, 2000).

Mortality in the state of Alabama due to excessive heat include a high of 125 in 1980 and yearly deaths since 1994 are charted in Figure 1 (ADPH, 2005, 2010, 2012b; NOAA, 2012). Most of the victims during the 1980 heat wave were elderly shut-ins who lacked air conditioning. A less intense heat wave in August 2007 resulted in 13 fatalities, while the majority of those treated at hospitals were of working age (26-50) and were working outside when they experienced heat stress (Pence & Stefkovich, 2008), suggesting the demographics of heat-related deaths may be changing.

HRI and fatalities in Alabama were recently added to the list of notifiable diseases required to be reported to the health department (ADPH, 2012a). Of the 809 HRI in 2012, 347 were reported as work related (ADPH, 2012a). Other state surveillance programs have also suggested work-related HRI contributes significantly to the overall numbers of...

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