Differences in Heat-Related Mortality by Citizenship Status: United States, 2005-2014

Low and high air temperature and cardiovascular risk

Temperature extremes are one facet of global warming caused by climate change. They have a broad impact on population health globally. Due to specific individual- and area-level factors, some subgroups of the population are at particular risk. Observational data has demonstrated that the association between temperature and mortality and cardiovascular mortality is U- or J-shaped. This means that beyond an optimal temperature, both low and high temperatures increase cardiovascular risk. In addition, there is emerging epidemiological data showing that climate change-related temperature fluctuations may be particularly challenging for cardiovascular health. Biological plausibility for these observations comes from the effect of cold, heat, and temperature fluctuations on risk factors for cardiovascular disease. Shared mechanisms of heat and cold adaptation include sympathetic activation, changes in vascular tone, increased cardiac strain, and inflammatory and prothrombotic stimuli. The confluence of these mechanisms can result in demand ischemia and/or atherosclerotic plaque rupture. In conclusion, public health and individual-level measures should be taken to protect susceptible populations, such as patients with risk factors and/or pre-existing cardiovascular disease, from the adverse effects of non-optimal temperatures. This review aims to provide an overview of the association between temperature extremes and cardiovascular disease through the lens of pathophysiology and observational data. It also highlights some specific meteorological aspects, gives insight to the interplay of air temperature and air pollution, touches upon social dimensions of climate change, and tries to give a brief outlook into what to expect from the future.

Secular trends in heat related illness and excess sun exposure rates across climatic zones in the United States from 2017 to 2022

Heat waves are a major public health challenge, yet the link between heat-related illness (HRI) and regional climate and geography is underexplored. We examined HRI and excess sun exposure incidence rates (IR) [95% confidence interval (CI) per 100,000 person-years], and their correlation with regional maximum temperatures across 9 US climatic zones 33,603,572 individuals were followed from 2017 to 2022. We observed 10,652 individuals with HRI diagnosis (median age: 49 years, 62.3% male). Seasonal peaks occurred during summer: highest overall IR (130.97 [119.93-142.75]) was recorded in July 2019, highest regional IR was reported in the South (186.04 [117.93-279.15]) during 2020. Strongest correlations between monthly maximum temperature and incidence of HRI were observed in the West (Pearson Correlation Coefficient (cor) = 0.854) and Southwest (cor = 0.832). In contrast, we observed 131,204 individuals with excess sun exposure (predominantly older adults [median age: 67 years], 52.3% female, 30% with history of cancer). Overall IR for sun exposure peaked in March 2021 (664.31 [644.84-684.21]) and lacked a consistent seasonal pattern. Sun exposure exhibited weaker correlations with regional temperatures, even in high-temperature regions like the West (cor = 0.305). These data indicate regional variations in HRI. With distinct at-risk groups for HRI and sun exposure, targeted regional interventions may be beneficial, such as heat safety protocols to reduce HRI risk and sun protection campaigns for older adults to mitigate sun exposure risk.

Occupational Heat Stress Among Migrant and Ethnic Minority Outdoor Workers: A Scoping Review

PURPOSE OF REVIEW

Migrant and ethnic minority (MEM) outdoor workers might be at increased risk for heat-related illnesses (HRI), due to environmental exposures, heavy physical work, limited control over workplace conditions and language and cultural barriers. This review aims to synthesize the literature on health impacts of occupational heat exposure among MEM outdoor workers, including risk factors, heat-related perception and behaviour and healthcare utilization.

RECENT FINDINGS

Seventy-six publications were included. Most were conducted in the US, where the weighted prevalence for at least one HRI symptom was 48.8%. These numbers were higher in most non-US countries. On average, in the US, 60.9% reported being concerned about heat and 60.4% having had HRI training. Many workers reported drinking more water when hot (91.7%) and feeling comfortable taking water breaks (92%) while fewer reported acclimatizing at the start of the season (43.7%) or changing working hours (34%) or activities (32.2%) due to heat. Qualitative studies reported reasons for working faster with less breaks, including fear of losing work and earning more when getting paid by the piece. Data on access to healthcare was limited. While research advances on MEM workers´ heat-related vulnerability, risk factors and healthcare utilization, there is a need to strengthen prevention efforts to reduce the burden of heat in this population.

The kidney under heat stress: a vulnerable state

PURPOSE OF REVIEW

This review examines the effects of occupational heat stress on kidney health. It focuses on the role of hyperthermia in the development of acute kidney injury (AKI) and its potential progression to chronic kidney disease of nontraditional etiology (CKDnt). We highlight the physiological mechanisms by which hyperthermia affects kidney function and discuss emerging preventive strategies.

RECENT FINDINGS

Hyperthermia places the kidneys in a vulnerable state. As body temperature increases, blood flow is directed toward the skin to aid in cooling, diverting it away from internal organs like the kidneys to support blood pressure regulation. At the same time, hyperthermia and dehydration increases energetic demand to promote fluid and electrolyte conservation. Collectively, this can create a localized supply-demand mismatch, resulting in tissue hypoxia that can damage kidney tissues. These findings highlight that heat hyperthermia can lead to subclinical kidney damage, with potential long-term implications for kidney health.

SUMMARY

Heat-induced AKI is a growing public health concern. Individuals engaged in manual labor with prolonged exposure are at risk of CKDnt. Interventions aimed to prevent hyperthermia show promise in mitigating the risk of AKI. Further research is necessary to refine these strategies and establish evidence-based guidelines for reducing heat-related kidney injuries.

Climate Change and Cardiovascular Disease: Who Is Vulnerable?

Climate change involves a shift in earth's climate indicators over extended periods of time due to human activity. Anthropogenic air pollution has resulted in trapping heat, contributing to global warming, which contributes to worsening air pollution through facilitating oxidizing of air constituents. It is becoming more evident that the effects of climate change, such as air pollution and ambient temperatures, are interconnected with each other and other environmental factors. While the relationship between climate change components and cardiovascular disease is well documented in the literature, their interaction with one another along with individuals' biological and social risk factors is yet to be elucidated. In this review, we summarize that pathophysiological mechanisms by ambient temperatures directly affect cardiovascular health and describe the most vulnerable subgroups, defined by age, sex, race, and socioeconomic factors. Finally, we provide guidance on the importance of integrating climate, environmental, social, and health data into common platforms to inform researchers and policies.

Modification effects of immigration status and comorbidities on associations of heat and heatwave with stroke morbidity

BACKGROUND

Heat and heatwave have been associated with stroke morbidity, but it is still unclear whether immigrants from different geographic regions and patients with comorbidity are more vulnerable to heat and heatwave.

METHODS

Time-stratified case-crossover design combined with generalized additive quasi-Poisson models were used to quantify the relative risks (RRs) of heat and heatwave on first-ever stroke morbidity during 0-7 lag days. Attributable fractions (AFs) were estimated to assess the first-ever stroke morbidity burden due to heat and heatwave. Stratified analyses for sex, age, disease subtypes, resident characteristics, and comorbidity type were performed to identify potential modification effects.

RESULTS

Heat and heatwave were associated with first-ever stroke morbidity, with the AF of 2.535% (95% empirical confidence interval (eCI) = 0.748, 4.205) and 2.409% (95% confidence interval (CI) = 1.228, 3.400), respectively. Among northern and southern immigrants, the AF for heat was 2.806% (0.031, 5.069) and 2.798% (0.757, 4.428), respectively, and the AF for heatwave was 2.918% (0.561, 4.618) and 2.387% (1.174, 3.398), respectively, but the effects of both on natives were statistically insignificant. Among patients with hypertension, dyslipidemia, or diabetes, the AF for heat was 3.318% (1.225, 5.007), 4.237% (1.037, 6.770), and 4.860% (1.171, 7.827), respectively, and the AF for heatwave was 2.960% (1.701, 3.993), 2.771% (0.704, 4.308), and 2.652% (0.653, 4.185), respectively. However, the effects of both on patients without comorbidity were statistically insignificant.

CONCLUSION

Heat and heatwave are associated with an increased risk of first-ever stroke morbidity among immigrants and those with comorbid hypertension, dyslipidemia, or diabetes, with the effects primarily due to non-native individuals.

DATA ACCESS STATEMENT

The author(s) are not authorized to share the data.

Effects of extreme weather on health in underserved communities

Increased fossil fuel use has increased carbon dioxide concentrations leading to global warming and climate change with increased frequency and intensity of extreme weather events such as thunderstorms, wildfires, droughts, and heat waves. These changes increase the risk of adverse health effects for all human beings. However, these experiences do not affect everyone equally. Underserved communities, including people of color, the elderly, people living with chronic conditions, and socioeconomically disadvantaged groups, have greater vulnerability to the impacts of climate change. These vulnerabilities are a result of multiple factors such as disparities in health care, lower educational status, and systemic racism. These social inequities are exacerbated by extreme weather events, which act as threat multipliers increasing disparities in health outcomes. It is clear that without human action, these global temperatures will continue to increase to unbearable levels creating an existential crisis. There is now global consensus that climate change is caused by anthropogenic activity and that actions to mitigate and adapt to climate change are urgently needed. The 2015 Paris Accord was the first truly global commitment that set goals to limit further warming. It also aimed to implement equity in action, founded on the principle of common but differentiated responsibilities. Meeting these goals requires individual, community, organizational, national, and global cooperation. Health care professionals, often in the frontline with firsthand knowledge of the health impacts of climate change, can play a key role in advocating for just and equitable climate change adaptation and mitigation policies.

Facilitators and Barriers for Keeping Cool in an Urban Heat Island: Perspectives from Residents of an Environmental Justice Community

Background

Extreme heat is a leading cause of morbidity and mortality during summer months in the United States. Risk of heat exposure and associated health outcomes are disproportionately experienced by people with lower incomes, people of color, and/or immigrant populations.

Methods

As qualitative research on the experiences of residents in heat islands is limited, this community-based study examined barriers and coping strategies for keeping cool among residents of Chelsea and East Boston, Massachusetts-environmental justice (EJ) areas that experience the urban heat island effect-through semistructured interviews and qualitative content analysis.

Results

Results indicate that all participants (n = 12) had air conditioning, but high energy bills contributed to low use. Eight participants were self-described heat-sensitive, with five experiencing poor health in heat. In addition, nine reported insufficient hydration due to work schedules, distaste of water, or perceptions of it being unsafe.

Discussion

This research highlights the importance of understanding perceptions of residents in EJ communities to contextualize vulnerability and identify multipronged heat coping strategies and targeted interventions.

Association of Temperature Thresholds with Heat Illness- and Cardiorespiratory-Related Emergency Visits during Summer Months in Alaska

BACKGROUND

Recent record-breaking hot temperatures in Alaska have raised concerns about the potential human health implications of heat exposure among this unacclimated population.

OBJECTIVES

We estimated cardiorespiratory morbidity associated with days above summer (June-August) heat index (HI, apparent temperature) thresholds in three major population centers (Anchorage, Fairbanks, and the Matanuska-Susitna Valley) for the years 2015-2019.

METHODS

We implemented time-stratified case-crossover analyses of emergency department (ED) visits for International Classification of Diseases, 10^th Revision codes indicative of heat illness and major cardiorespiratory diagnostic codes using data from the Alaska Health Facilities Data Reporting Program. Using conditional logistic regression models, we tested maximum hourly HI temperature thresholds between 21.1°C (70°F) and 30°C (86°F) for a single day, 2 consecutive days, and the absolute number of previous consecutive days above the threshold, adjusting for the daily average concentration of particulate matter ≤2.5μg.

RESULTS

There were increased odds of ED visits for heat illness above a HI threshold as low as 21.1°C (70°F) [odds ratio (OR)=13.84; 95% confidence interval (CI): 4.05, 47.29], and this increased risk continued for up to 4 d (OR=2.43; 95% CI: 1.15, 5.10). Asthma and pneumonia were the only respiratory outcomes positively associated with the HI: ED visits for both were highest the day after a heat event (Asthma: HI>27°C(80°F) OR=1.18; 95% CI: 1.00, 1.39; Pneumonia: HI>28°C(82°F) OR=1.40; 95% CI: 1.06, 1.84). There was a decreased odds of bronchitis-related ED visits when the HI was above thresholds of 21.1-28°C (70-82°F) across all lag days. We found stronger effects for ischemia and myocardial infarction (MI) than for respiratory outcomes. Multiple days of warm weather were associated with an increased risk of health impacts. For each additional preceding day above a HI of 22°C (72°F), the odds of ED visits related to ischemia increased 6% (95% CI: 1%, 12%); for each additional preceding day above a HI of 21.1°C (70°F), the odds of ED visits related to MI increased 7% (95% CI: 1%, 14%).

DISCUSSION

This study demonstrates the importance of planning for extreme heat events and developing local guidance for heat warnings, even in areas with historically mild summertime climates. https://doi.org/10.1289/EHP11363.

The Epidemiology and Geographic Patterns of Natural Disaster and Extreme Weather Mortality by Race and Ethnicity, United States, 1999-2018

OBJECTIVES

The adverse effects that racial and ethnic minority groups experience before, during, and after disaster events are of public health concern. The objective of this study was to examine disparities in the epidemiologic and geographic patterns of natural disaster and extreme weather mortality by race and ethnicity.

METHODS

We used mortality data from the Centers for Disease Control and Prevention from January 1, 1999, through December 31, 2018. We defined natural disaster and extreme weather mortality based on International Classification of Diseases, 10th Revision codes X30-X39. We calculated age-adjusted mortality rates by race, ethnicity, and hazard type, and we calculated age-adjusted mortality rate ratios by race, ethnicity, and state. We used geographic mapping to examine age-adjusted mortality rate ratios by race, ethnicity, and state.

RESULTS

Natural disasters and extreme weather caused 27 335 deaths in the United States during 1999-2018. Although non-Hispanic White people represented 68% of total natural disaster and extreme weather mortality, the mortality rate per 100 000 population among non-Hispanic Black people was 1.87 times higher (0.71) and among non-Hispanic American Indian/Alaska Native people was 7.34 times higher (2.79) than among non-Hispanic White people (0.38). For all racial and ethnic groups, exposure to extreme heat and cold were the 2 greatest causes of natural disaster and extreme weather mortality. Racial and ethnic disparities in natural disaster and extreme weather mortality were highest in the South, Southwest, Mountain West, and Upper Midwest.

CONCLUSIONS

Racial and ethnic minority populations have a greater likelihood of mortality from natural disaster or extreme weather events than non-Hispanic White people. Our study strengthens the current knowledge base on these disparities and may inform and improve disaster preparedness and response efforts.

Racial Disparities in Climate Change-Related Health Effects in the United States

PURPOSE OF REVIEW

Climate change is causing warming over most parts of the USA and more extreme weather events. The health impacts of these changes are not experienced equally. We synthesize the recent evidence that climatic changes linked to global warming are having a disparate impact on the health of people of color, including children.

RECENT FINDINGS

Multiple studies of heat, extreme cold, hurricanes, flooding, and wildfires find evidence that people of color, including Black, Latinx, Native American, Pacific Islander, and Asian communities are at higher risk of climate-related health impacts than Whites, although this is not always the case. Studies of adults have found evidence of racial disparities related to climatic changes with respect to mortality, respiratory and cardiovascular disease, mental health, and heat-related illness. Children are particularly vulnerable to the health impacts of climate change, and infants and children of color have experienced adverse perinatal outcomes, occupational heat stress, and increases in emergency department visits associated with extreme weather. The evidence strongly suggests climate change is an environmental injustice that is likely to exacerbate existing racial disparities across a broad range of health outcomes.

The Intersection of Immigrant and Environmental Health: A Scoping Review of Observational Population Exposure and Epidemiologic Studies

BACKGROUND

Transnational immigration has increased since the 1950s. In countries such as the United States, immigrants now account for > 15 % of the population. Although differences in health between immigrants and nonimmigrants are well documented, it is unclear how environmental exposures contribute to these disparities.

OBJECTIVES

We summarized current knowledge comparing immigrants' and nonimmigrants' exposure to and health effects of environmental exposures.

METHODS

We conducted a title and abstract review on articles identified through PubMed and selected those that assessed environmental exposures or health effects separately for immigrants and nonimmigrants. After a full text review, we extracted the main findings from eligible studies and categorized each article as exposure-focused, health-focused, or both. We also noted each study's exposure of interest, study location, exposure and statistical methods, immigrant and comparison groups, and the intersecting socioeconomic characteristics controlled for.

RESULTS

We conducted a title and abstract review on 3,705 articles, a full text review on 84, and extracted findings from 50 studies. There were 43 studies that investigated exposure (e.g., metals, organic compounds, fine particulate matter, hazardous air pollutants) disparities, but only 12 studies that assessed health disparities (e.g., mortality, select morbidities). Multiple studies reported higher exposures in immigrants compared with nonimmigrants. Among immigrants, studies sometimes observed exposure disparities by country of origin and time since immigration. Of the 50 studies, 43 were conducted in North America.

DISCUSSION

The environmental health of immigrants remains an understudied area, especially outside of North America. Although most identified studies explored potential exposure disparities, few investigated subsequent differences in health effects. Future research should investigate environmental health disparities of immigrants, especially outside North America. Additional research gaps include the role of immigrants' country of origin and time since immigration, as well as the combined effects of immigrant status with intersecting socioeconomic characteristics, such as race/ethnicity, income, and education attainment. https://doi.org/10.1289/EHP9855.

Extreme Heat and COVID-19: A Dual Burden for Farmworkers

Currently, there is an extensive literature examining heat impacts on labor productivity and health, as well as a recent surge in research around COVID-19. However, to our knowledge, no research to date examines the dual burden of COVID-19 and extreme heat on labor productivity and laborers' health and livelihoods. To close this research gap and shed light on a critical health and livelihood issue affecting a vulnerable population, we urge researchers to study the two topics in tandem. Because farmworkers have a high incidence of COVID-19 infections and a low rate of inoculation, they will be among those who suffer most from this dual burden. In this article, we discuss impacts from extreme heat and COVID-19 on farm laborers. We provide examples from the literature and a conceptual framework showing the bi-directional nature of heat impacts on COVID-19 and vice versa. We conclude with questions for further research and with specific policy recommendations to alleviate this dual burden. If implemented, these policies would enhance the wellbeing of farmworkers through improved unemployment benefits, updated regulations, and consistent implementation of outdoor labor regulations. Additionally, policies for farmworker-related health needs and cultural aspects of policy implementation and farmworker outreach are needed. These and related policies could potentially reduce the dual burden of COVID-19 and extreme heat impacts while future research explores their relative cost-effectiveness.

Environmental Health Threats to Latino Migrant Farmworkers

Approximately 75% of farmworkers in the United States are Latino migrants, and about 50% of hired farmworkers do not have authorization to work in the United States. Farmworkers face numerous chemical, physical, and biological threats to their health. The adverse effects of these hazards may be amplified among Latino migrant farmworkers, who are concurrently exposed to various psychosocial stressors. Factors such as documentation status, potential lack of authorization to work in the United States, and language and cultural barriers may also prevent Latino migrants from accessing federal aid, legal assistance, and health programs. These environmental, occupational, and social hazards may further exacerbate existing health disparities among US Latinos. This population is also likely to be disproportionately impacted by emerging threats, including climate change and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Latino migrant farmworkers are essential to agriculture in the United States, and actions are needed to protect this vulnerable population.

Developing a geospatial measure of change in core temperature for migrating persons in the Mexico-U.S. border region

Although heat exposure is the leading cause of mortality for undocumented immigrants attempting to traverse the Mexico-U.S. border, there has been little work in quantifying risk. Therefore, our study aims to develop a methodology projecting increase in core temperature over time and space for migrants in Southern Arizona using spatial analysis and remote sensing in combination with the heat balance equation-adapting physiological formulae to a multi-step geospatial model using local climate conditions, terrain, and body specifics. We sought to quantitatively compare the results by demographic categories of age and sex and qualitatively compare them to known terrestrial conditions and prior studies of those conditions. We demonstrated a more detailed measure of risk for migrants than those used most recently: energy expenditure and terrain ruggedness. Our study not only gives a better understanding of the 'funnel effect' mechanisms, but also provides an opportunity for relief and rescue operations.

Compounded Heat and Fire Risk for Future U.S. Populations

Climate change is increasing the risk of extreme events, resulting in social and economic challenges. I examined recent past (1971–2000), current and near future (2010–2039), and future (2040–2069) fire and heat hazard combined with population growth by different regions and residential densities (i.e., exurban low and high densities, suburban, and urban low and high densities). Regional values for extreme fire weather days varied greatly. Temperature and number of extreme fire weather days increased over time for all residential density categories, with the greatest increases in the exurban low-density category. The urban high-density category was about 0.8 to 1 °C cooler than the urban low-density category. The areas of the urban and suburban density categories increased relative to the exurban low-density category. Holding climate change constant at 1970–2000 resulted in a temperature increase of 0.4 to 0.8 °C by 2060, indicating future population increases in warmer areas. Overall, U.S. residents will experience greater exposure to fire hazard and heat over time due to climate change, and compound risk emerges because fire weather and heat are coupled and have effects across sectors. Movement to urban centers will help offset exposure to fire but not heat, because urban areas are heat islands; however, urban high-density areas had lower base temperatures, likely due to city locations along coastlines. This analysis provides a timely look at potential trends in fire and heat risk by residential density classes due to the expansion and migration of US populations.

Socio-geographic disparity in cardiorespiratory mortality burden attributable to ambient temperature in the United States

Compared with relative risk, attributable fraction (AF) is more informative when assessing the mortality burden due to some environmental exposures (e.g., ambient temperature). Up to date, however, available AF-based evidence linking temperature with mortality has been very sparse regionally and nationally, even for the leading mortality types such as cardiorespiratory deaths. This study aimed to quantify national and regional burden of cardiorespiratory mortality (CRM) attributable to ambient temperature in the USA, and to explore potential socioeconomic and demographic sources of spatial heterogeneity between communities. Daily CRM and weather data during 1987-2000 for 106 urban communities across the mainland of USA were acquired from the publicly available National Morbidity, Mortality and Air Pollution Study (NMMAPS). We did the data analysis using a three-stage analytic approach. We first applied quasi-Poisson regression incorporated with distributed lag nonlinear model to estimate community-specific temperature-CRM associations, then pooled these associations at the regional and national level through a multivariate meta-analysis, and finally estimated the temperature-AF of CRM and performed subgroup analyses stratified by community-level characteristics. Both low and high temperatures increased short-term CRM risk, while temperature-CRM associations varied by regions. Nationally, the fraction of cardiorespiratory deaths caused by the total non-optimum, low, and high temperatures was 7.58% (95% empirical confidence interval, 6.68-8.31%), 7.15% (6.31-7.85%), and 0.43% (0.37-0.46%), respectively. Greater temperature-AF was identified in two northern regions (i.e., Industrial Midwest and North East) and communities with lower temperature and longitude, higher latitude, and moderate humidity. Additionally, higher vulnerability appeared in locations with higher urbanization level, more aging population, less White race, and lower socioeconomic status. Ambient temperature may be responsible for a large fraction of cardiorespiratory deaths. Also, temperature-AF of CRM varied considerably by geographical and climatological factors, as well as community-level disparity in socioeconomic status.

Without Warning: Worker Deaths From Heat 2014-2016

Worker deaths from heat exposure are unlike heat deaths in the general population; workers tend to be outside in variable temperatures and younger than sixty-five years. Climate change will increase the frequency, duration, and variability of hot temperatures. Public health warning systems, such as the Heat Index of the National Weather Service, do not generally account for workers' greater likelihood of exposure to direct sunlight or exertion. Only 28% of the 79 worker heat-related fatalities during 2014-2016 occurred on days when the National Weather Service warning would have included the possibility of fatal heat stroke. Common heat illness prevention advice ignores workers' lack of control over their ability to rest and seek cooler temperatures. Additionally, acclimatization, or phased-in work in the heat, may be less useful given temperature variability under climate change. Workers' vulnerability and context of heat exposure should inform public health surveillance and response to prevent heat illness and death.