Heat-Related Emergency Department Visits - United States, May-September 2023.

Unprecedented heat waves can affect all persons, but some are more sensitive to the effects of heat, including children and adults with underlying health conditions, pregnant women, and outdoor workers. Many regions of the United States experienced record-breaking high temperatures in 2023, with populations exposed to extremely high temperatures for prolonged periods. CDC examined emergency department (ED) visits associated with heat-related illness (HRI) from the National Syndromic Surveillance Program and compared daily HRI ED visit rates during the warm-season months (May-September) of 2023 with those during 2018-2022. In the 2023 warm-season months, daily HRI ED visit rates peaked in several regions and remained elevated for a prolonged duration. More males than females sought care in EDs for HRI, especially males aged 18-64 years. CDC issued multiple public health alerts using the Epidemic Information Exchange system to bring attention to increases in ED utilization for HRI. Deaths and illnesses associated with heat exposure are a continuing public health concern as climate change results in longer, hotter, and more frequent episodes of extreme heat. Near real-time monitoring of weather conditions and adverse health outcomes can guide public health practitioners' timing of risk communication and implementation of prevention measures associated with extreme heat.

Association Between Acute Kidney Injury Hospital Visits and Environmental Heat Stress at a Nicaraguan Sugarcane Plantation.

BACKGROUND: Mesoamerican sugarcane cutters are at a high risk of chronic kidney disease of non-traditional origin, a disease likely linked to heat-related acute kidney injury (AKI). Studies in general populations have described a positive association between high environmental temperatures and clinically assessed kidney outcomes, but there are no studies in occupational settings. METHOD: We accessed routine records of clinically diagnosed AKI (AKI-CD) and wet bulb globe temperatures (WBGT) at a large Nicaraguan sugarcane plantation and modeled the relationship between these using negative binomial regression. A rest-shade-hydration intervention was gradually enhanced during the study period, and efforts were made to increase the referral of workers with suspected AKI to healthcare. RESULTS: Each 1°C WBGT was associated with an 18% (95% confidence interval [CI]: [4, 33%]) higher AKI-CD rate on the same day and a 14% (95% CI [-5, 37%]) higher rate over a week. AKI-CD rates and severity, and time between symptoms onset and diagnosis decreased during the study period, that is, with increasing rest-shade-hydration intervention. Symptoms and biochemical signs of systemic inflammation were common among AKI-CD cases. DISCUSSION: Occupational heat stress, resulting from heavy work in environmental heat, was associated with a higher rate of clinically diagnosed AKI in a population at risk of CKDnt. Promoting rest-shade-hydration may have contributed to reducing AKI rates during the study period. Occupational health and safety personnel have key roles to play in enforcing rest, shade, and hydration practices, referring workers with suspected AKI to healthcare as well as collecting and analyzing the data needed to support workplace heat stress interventions.

Impact of heat stress on health-related symptoms and physiological changes among workers at a palm oil mill in Mukah, Sarawak, Malaysia.

INTRODUCTION: The palm oil (PO) industry is one of the most important sectors in the Malaysian economy. Workers at PO mills are, however, at risk for a number of health and safety issues, including heat stress, as the PO is one of the industries with high heat exposure. Heat stress occurs when a person's body cannot get rid of excess heat. Heat stress can result in heat cramps, heat exhaustion, heat rash, and heat stroke. It also results in physiological and psychological changes that can have an impact on a worker's performance. Therefore, this study aimed to evaluate the impact of heat stress on health-related symptoms and physiological changes among workers in a PO mill. MATERIALS AND METHODS: This cross-sectional study was conducted in a PO mill located in Mukah, Sarawak, Malaysia. Thirty-one workers from the four workstations (sterilizer, boiler, oil, and engine rooms) were selected as the respondents in this study. Wet Bulb Globe Thermometer was used in this study to measure the environmental temperature (WBGTin). Body core temperature (BCT), blood pressure (BP), and heart rate (HR) were recorded both before and after working in order to assess the physiological effects of heat stress on workers. A set of questionnaires were used to determine sociodemographic characteristics of the respondents and their symptoms related to heat stress. Data were then analyzed using SPSS Ver28. RESULTS: The WBGTin was found to be above the ACGIH threshold limit value of heat stress exposure in the engine room, sterilizer, and boiler workstations (>28.0°C). Additionally, there was a significant difference in the worker's BCT in these three workstations before and after work (p<0.05). Only the systolic BP and HR of those working at the boiler workstation showed significant difference between before and after work (p<0.05). The most typical symptoms that workers experience as a result of being exposed to heat at work include headache and fatigue. However, statistical analysis using Spearman Rho's test showed that there is no correlation between heat stress level with physiological changes and health-related symptoms among study respondents (p>0.05). CONCLUSION: Results of the present study confirmed that workers in PO mill were exposed to high temperatures while at work. Although the evidence indicates the physiological parameters in general are not significantly affected while working, it also demonstrated that worker's body adapts and acclimates to the level of heat. Even so, precautions should still be taken to reduce future heat exposure. It is recommended that a physiological study be carried out that focuses on cognitive function impairment to support the evidence regarding the effects of heat stress on PO mill workers.

Heat exposure as a cause of injury and illness in mine industry workers.

The objective of this study was to explore the association between ambient temperature and injuries and illnesses experienced by mine industry workers. Eleven years of de-identified data from a mine industry company in Australia was explored in regards to injuries and illnesses occurring due to outdoor exposure. Each case was filtered for reported symptoms, and meteorological data to match the location of the mine site and date reported were sourced. Of the 18 931 injuries and illnesses observed over the 11-year period, 151 cases of heat-related illness due to outdoor exposure were reported. Twenty-five conditions/symptoms of heat-illness were found, with the most prevalent being dehydration (n = 81), followed by heat rash (n = 40), dizziness (n = 24), and headache (n = 23). The mean number of symptoms reported by each worker was 2 ± 1. There was a positive correlation between ambient temperature and injuries/illnesses (r2 = 0.89, P < 0.001), where, as temperature increased so did the number of reported heat-related illnesses. Underreporting of heat-related illness and injury in the mining industry is likely, which is a risk to the health and wellbeing of employees. Workers require industry specific training about the severity of heat stress and the associated prevention strategies.

Association between the experience of exertional heat illness (EHI) and living conditions of collegiate student athletes.

Exertional heatstroke (EHS), a severe form of exertional heat illness (EHI), is the third leading cause of death in athletes; thus, early detection and prevention of EHI can help prevent EHS, which is a life-threatening condition. This study aimed to clarify the association between the cognizance of experiencing EHI and living conditions and specific EHI symptoms among collegiate athletes. This study was conducted in October 2022 by administering a questionnaire to 237 male collegiate athletes. Of the 215 (90.7%) respondents, 197 (91.6%) provided valid responses; among them, 88 (44.7%) responded they had experienced EHI, while 109 (55.3%) had not. A history of medical examinations due to EHI, having experienced headaches during summer activities, and having read the EHI manual were factors indicating cognizance of EHI. The number of times meals containing a staple food, main dish, and side dish were eaten in a day was a factor in preventing EHI. Early detection of EHI is important for its prevention, and it is important that athletes themselves have knowledge of symptoms and can correctly self-diagnose EHI. Emphasizing the potential of a well-balanced dietary intake has the potential to prevent EHI is crucial.

Outcomes for a Heat Illness Prevention Program in Outdoor Workers: A 9-Year Overview.

OBJECTIVE: To describe the outcomes effect of removing the medical surveillance component from a heat illness prevention program (HIPP) for outdoor workers from a Central Texas municipality. METHODS: Heat-related illness (HRI) frequency and workers' compensation (WC) cost were assessed retrospectively in a cohort of 329 workers from 2011-2019. During 2011-2017, the HIPP included training, acclimatization, and medical surveillance. In 2018-2019, a modified (mHIPP) was implemented that included training and acclimatization, but without medical surveillance. RESULTS: The HRI rate during HIPP averaged 19.5 per 1000 workers during the first 4 years, dropped to 1.01 per 1,000 workers over the next 3 years, (2015-2017), and increased during mHIPP, to 7.6 per 1,000 workers. DISCUSSION: Although the case increase during the mHIPP was small, medical surveillance may be an important component in lowering workforce HRI.

Heat exposure and chronic kidney disease: a temporal link in a Taiwanese agricultural county.

Heat stress-related kidney injury has drawn public health attention. This study explored the temporal relationships between impaired kidney function and preceding outdoor heat exposure Taiwan. Data of participants collected through a health screening program was used to assess the association between chronic kidney disease (CKD) and average ambient temperature with various time lag structures. A total of 1,243 CKD cases and 38,831 non-CKD participants were included in the study. After adjusting for demographic, socioeconomic, lifestyle factors, and comorbidities, CKD was positively associated with the ambient temperature within 1-9 months. The 9-month average ambient temperature yielded the highest odds ratio of CKD (OR = 1.22; 95% CI = 1.09-1.37). Furthermore, females and farmers were found to be more vulnerable to CKD risk after outdoor heat exposure. These findings suggest that the prevention of heat stress-related kidney injury should consider relevant time frames and focus on vulnerable populations.

Heat wave exposure and increased heat-related hospitalizations in young children in South Korea: A time-series study.

BACKGROUND: Numerous studies have investigated the association between heat wave exposure increased heat-related hospitalizations in the general population. However, little is known about heat-related morbidity in young children who are more vulnerable than the general population. Therefore, we aimed to evaluate the association between hospitalization for heat-related illness in children and heat wave exposure in South Korea. METHODS: We used the National Health Insurance Service (NHIS) database, which provides medical records from 2015 to 2019 in South Korea. We defined daily hospitalizations for heat-related illness of children younger than five years during the summer period (June to August). We considered the definition of heat waves considering the absolute temperature and percentile. A total of 12 different heat waves were used. A time-series analysis was used to investigate the association between heat wave exposure and heat-related hospitalization among children younger than five years. We used a two-stage design involving a meta-analysis after modeling by each region. RESULTS: We included 16,879 daily heat-related hospitalizations among children younger than five years. Overall, heat wave exposure within two days was most related for heat-related hospitalizations in young children. The relative risk (RR) due to heat wave exposure within two days (lag2) (12 definitions: 70th to 90th percentile of maximum temperature) ranged from 1.038 (95% confidence interval (CI): 0.971, 1.110) to 1.083 (95% CI: 1.036, 1.133). We found that boys were more vulnerable to heat exposure than girls. In addition, we found that urban areas were more vulnerable to heat exposure than rural areas. CONCLUSIONS: In our study, heat wave exposure during summer was found to be associated with an increased risk of hospitalization for heat-related illness among children younger than five years. Our findings suggest the need for summer heat wave management and prevention for children.

Perceived challenges and barriers for females working in the heat.

Given rising temperatures, globally, heat exposures and catastrophic heat illnesses are a major concern in laborer and industrial sectors. The purpose of this study was to evaluate the perceptions of females laboring in the heat regarding challenges and barriers encountered in their respective industries while working in the heat. A consensual qualitative research (CQR) design was employed to gain information related to participant occupational and job characteristics, feelings while working in the heat, adjustments made by employers when they work in the heat, and their experience working in the heat specific to their identified sex. Females were eligible to participate if they were currently employed in an environment that required them to work in the heat. Twelve females participated in a single, 45-60 min one-on-one semi-structured interview. Participants reported working in the manufacturing, agriculture, tourism, and railroad industries. Upon completion of data analysis, one primary theme was identified: heat stress mitigation strategies, which were further broken down into two subthemes of formal strategies provided by the employer and informal strategies driven by the employees. Participants indicated there was a lack of heat stress prevention strategies implemented by their employers, which resulted in employees creating their own strategies to protect themselves and their coworkers from heat stress. Results indicated there are limited heat stress prevention strategies that are provided in industries that include females working in the heat. Unique considerations should be made to protect this population from the dangers of heat stress and must go beyond workers protecting themselves.

Heat illness presentations to emergency departments in Western Sydney: surveillance for environmental, personal and behavioural risk factors.

OBJECTIVE: To pilot surveillance to describe environmental, personal and behavioural risk factors for people presenting to hospital emergency departments (EDs) with heat illness. METHODS: We conducted a retrospective case series and telephone interview study of people presenting to EDs across South Western Sydney, Western Sydney and Nepean Blue Mountains Local Health Districts with heat illness over the 2017/18 and 2018/19 summer periods (1 December to 28 February). We used the Public Health Rapid Emergency Disease Syndromic Surveillance (PHREDSS) 'heat problems' syndrome to identify people with heat illness and medical records to find contact details. We developed a detailed questionnaire instrument to guide the telephone interview. RESULTS: A total of 129 individuals presented with 'heat problems' (57 in 2017/18 and 72 in 2018/19). The median age was 44 years (range 1-89 years). Most attended hospitals via the NSW Ambulance Service (58%) or private car (40%). Of the total, 53% were classified as triage category 3 (potentially life-threatening), 27% as category 4 (potentially serious) and 16% as category 2 (imminently life-threatening). The main supplementary codes were heat exhaustion (35%), heat syncope (39%), and heat stroke (30%). The majority were discharged from the emergency department after completing treatment (73%), with 21% requiring admission. A total of 38 follow-up interviews were completed (29% response rate). Almost all individuals were exposed to heat outside their home environment: 11 (29%) were engaged in paid work, 5 (13%) in outdoor housework, and 10 (26%) in outdoor recreational activities. CONCLUSION: Our pilot surveillance study successfully collected home, local environment and behavioural risk factors on a small cohort presenting with 'heat problems' to EDs in Western Sydney during the summer months. Most were exposed to heat outdoors while engaged in work or recreation outside the home, and were preventable.

A pilot heat-health warning system co-designed for a subtropical city.

Significant heat-related casualties underlie the urgency of establishing a heat-health warning system (HHWS). This paper presents an evidence-based pilot HHWS developed for Taipei City, Taiwan, through a co-design process engaging stakeholders. In the co-design process, policy concerns related to biometeorology, epidemiology and public health, and risk communication aspects were identified, with knowledge gaps being filled by subsequent findings. The biometeorological results revealed that Taipei residents were exposed to wet-bulb globe temperature (WBGT) levels of health concern for at least 100 days in 2016. The hot spots and periods identified using WBGT would be missed out if using temperature, underlining the importance of adopting an appropriate heat indicator. Significant increases in heat-related emergency were found in Taipei at WBGT exceeding 36°C with reference-adjusted risk ratio (RaRR) of 2.42, taking 30°C as the reference; and residents aged 0-14 had the highest risk enhancement (RaRR = 7.70). As for risk communication, occurring frequency was evaluated to avoid too frequent warnings, which would numb the public and exhaust resources. After integrating knowledge and reconciling the different preferences and perspectives, the pilot HHWS was co-implemented in 2018 by the science team and Taipei City officials; accompanying responsive measures were formulated for execution by ten city government departments/offices. The results of this pilot served as a useful reference for establishing a nationwide heat-alert app in 2021/2022. The lessons learnt during the interactive co-design processes provide valuable insights for establishing HHWSs worldwide.

The Effects Of Heat Stress On Haematological Parameters In Production Department Of Food Industry Employees.

OBJECTIVE: To investigate the effects of heat stress on some haematological parameters among food industry employees working in the production department. METHODS: The ambispective, single-centre, case-control study was conducted from December 1, 2016, to June 6, 2018, at Istanbul Gedik University and the Okan University, Istanbul, which is part of the Marmara region of Turkey. The study comprised subjects of either gender aged 22-57 years. Those working in the food industry were the cases in group A, while healthy controls formed group B. Within group A, subjects who were office workers formed subgroup A1, while those in the production department working in the heat treatment areas exposed to high temperatures formed subgroup A2. Heat stress in the environment was evaluated using the Wet Bulb Globe Temperature index. Peripheral blood haemoglobin and platelet levels, neutrophil-lymphocyte ratio and platelet-lymphocyte ratio were compared between the cases and the controls. Data was analysed using SPSS 22. RESULTS: Of the 257 subjects, 139(54.1%) were women and 118 (45.9%) were men. The overall mean age was 35.07±7.32 years. There were 143(55.6%) subjects in group A and 114(44.4%) in group B. Within group A, 19(13.3%) subjects were in subgroup A1 and 124(86.7%) in subgroup A2. The mean working duration for group A was 9.95±4.37 years (range 5-24 years). Haemoglobin and platelet levels were significantly lower and the neutrophil- lymphocyte ratio was significantly higher in subgroup A2 compared to those in subgroup A1 and group B (p<0.05). There was no significant difference in terms of platelet-lymphocyte ratio (p=0.486). CONCLUSIONS: Differences in haematological parameters were significantly different in individuals who worked in the production department and were exposed to heat stress compared to those who did not.

Comparison of women's heat risk profiles among those working in indoor and outdoor sectors.

Rising temperatures and heat events may affect workers, especially women, by increasing the risk of Heat Related Illnesses (HRIs). We conducted a cross-sectional study among 903 women in outdoor and indoor sectors. We measured Wet Bulb Globe Temperature (WBGT) and physiological Heat Strain Indicators (HSI), as well as self-reported symptoms of HRIs using a HOTHAPS questionnaire. Multivariate Logistic Regression models were used to compare the heat risks. WBGT exposures were high in both the outdoor (Avg. WBGT = 28.8 °C ± 2.4 °C) and indoor (Avg. WBGT = 28.7 °C ± 3.5 °C) sectors. Outdoor Women Workers (OWW) reported higher HRI symptoms (94%vs.81%), and heat exposures were positively correlated with HRIs (AOR: 3.7; 95%CI: 2.4-6.1). OWW showed a 1.5-fold higher risk of measured HSI above safe limits (95%CI: 1.1-2.1) and a 2.1-fold higher risk of urogenital issues (95%CI: 2.1-3.8) than Indoor Women Workers (IWW). Due to direct sun exposure, intensive labor, and a lack of welfare facilities, OWW has a higher HRI risk.

A 43-year of human thermal comfort in Central Africa.

In this study, the human thermal stress was quantified across Central Africa (C.A.) using the Universal Thermal Climate Index (UTCI). Although many of the documented studies on the use of UTCI in relation to human health are currently restricted to countries in the northern hemisphere, this contribution constitutes a prerequisite of information for future research in the region. To mitigate the problem of lack of field data in the Central African sub-region, we downloaded UTCI data via the ERA5 reanalysis portal. Based on this data source, we have explored the spatiotemporal characteristics and the resulting behaviour at annual, seasonal and monthly scales in Central Africa over the period 1982 to 2022. On these different scales, 4 of the 10 UTCI thermal stress categories were experienced, ranging from mild cold stress to strong heat stress. Spatially, cases of moderate heat stress were the most widespread, with cases of strong intensity occurring in a few isolated areas in the centre, east and west. Slight cold stress is confined to the south-east domain, particularly in autumn and winter. From 1982 to 2022, heat stress has increased significantly in the region, with peaks observed in January and October; very few areas have been spared the phenomenon of thermal stress. However, a slight decreasing trend was noticed along coastal regions and the south of C.A. Thereafter, the trend values showed the degree of C.A. vulnerability to global warming, and thus appropriate measures should be taken in relation to outdoor occupations and its impacts on the population of this region.

Inequality in behavioural heat adaptation: an empirical study with mobility data from the transport system in New York City, NY, USA.

BACKGROUND: Heat exposure, which can negatively affect human health and wellbeing, is heterogeneous within US cities. However, little is known about who can avoid heat stress by adjusting their everyday behaviour. We aimed to analyse the effect of ambient temperature on mobility, specifically subway (ie, the underground railway system) use, in New York City, NY, USA, during 2014-19. METHODS: For this empirical study, subway use across New York City was measured with turnstile data from the New York City Metropolitan Transportation Authority between Jan 1, 2014, and Dec 31, 2019. Passenger numbers were then aggregated to the zip code tabulation area (ZCTA) level. Daily observational climate data were obtained from the US National Weather Service between Jan 1, 2014, and Dec 31, 2019. Socioeconomic data at the ZCTA level originated from the American Community Survey 2019. We extracted data on population age, ethnicity, commuting, employment, median household income, rent, and health-insurance coverage. We used a fixed-effects panel-regression model to assess the influence of temperature on subway use in New York City, which was the main outcome of our study. FINDINGS: We obtained data for 438 subway stations across New York City. After data cleaning and preprocessing, the final aggregated data sample consisted of 238 508 instances of subway use in 1955 days across 6 years for 122 ZCTAs, with 168 days missing in the raw data and 67 days removed as outliers. The results of the fixed-effects panel-regression analysis showed a strong, non-linear effect of daily maximum temperature on subway use. Subway use was highest at 11·5°C and substantially decreased for temperatures that were colder and warmer than that, with reductions reaching 6·5% (95% CI 2·5-10·5) for the coldest temperature (ie, -6·5°C) and 10·5% (6·0-14·0) for the hottest temperature (ie, 34·5°C). Reductions differed between weekdays and weekends, when residents generally had more freedom to adjust their behaviour. Neighbourhoods that were at a socioeconomic disadvantage experienced smaller or no reductions in mobility in heat; mobility increased in neighbourhoods with beach access. INTERPRETATION: Our study showed that temperature had a strong, non-linear effect on subway use, but the magnitude of the effect on subway use was heterogeneous across areas of the city on warm days. Weaker avoidance of heat stress correlated with less privilege, indicating compounding health risks. Everyday behavioural adaptation to heat is therefore an effect pathway that contributes to unequal heat effects and should be explored in future research. FUNDING: The Volkswagen Foundation and the Werner Siemens Foundation.

Heat Exhaustion and Heat Stroke Among Active Component Members of the U.S. Armed Forces, 2018-2022.

The most serious types of heat illness, heat exhaustion and heat stroke, are occupational hazards of the military's training and operational environments. These conditions can be mitigated with appropriate situational aware-ness and effective countermeasures. In 2022, the crude incidence rates of heat stroke and heat exhaustion among active component service members were 32.1 and 147.7 per 100,000 person-years, respectively. The rates of incident heat stroke and heat exhaustion generally declined during the 2018 to 2022 surveillance period. In 2022, those at highest risk were men, those younger than age 20, Marine Corps and Army members, recruit trainees, and those in combat-specific occupations. Leaders, training cadres, and supporting medical personnel must inform their supervised and supported service members of heat illness risks, preventive measures, early signs and symptoms, and first-responder actions.

Exertional Rhabdomyolysis Among Active Component Members of the U.S. Armed Forces, 2018-2022.

Exertional rhabdomyolysis is a pathologic muscle breakdown associated with strenuous physical activity. A largely preventable condition, it persists as an occupational hazard of military training and operations, especially in high heat environments among individuals exerting themselves to endurance limits. During the 5-year surveillance period, unadjusted incidence rates of exertional rhabdomyolysis among U.S. service members declined by approximately 15%, from 43.1 cases per 100,000 person-years (p-yrs) in 2018 to 36.5 cases per 100,000 p-yrs in 2022. Consistent with prior reports, subgroup- specific rates in 2022 were highest among men, those younger than 20 years, non-Hispanic Black service members, Marine Corps or Army members, and those in combat-specific and "other" occupations. Recruit trainees had the highest rates of exertional rhabdomyolysis in 2021 and 2022, with incidence rates 10 times higher than all other service members. Prompt recognition of the symptoms of exertional rhabdomyolysis (muscular pain or swelling, limited range of motion, or the excretion of darkened urine after strenuous physical activity, especially in hot, humid weather) by health care providers is crucial to avoid the most severe consequences of this potentially life-threatening condition.

Exertional Hyponatremia Among Active Component Members of the U.S. Armed Forces, 2007-2022.

Exertional hyponatremia occurs either during or following periods of heavy exertion, when losses of water and electrolytes due to the body's normal cooling mechanisms are replaced only with water. Hyponatremia can lead to death or serious morbidity if left untreated. Between 2007 and 2022, there were 1,690 diagnoses of exertional hyponatremia among active component service members, for an overall incidence rate of 7.9 cases per 100,000 person-years (p-yrs). Those younger than 20 years or older than 40, non-Hispanic White service members, Marine Corps members, and recruit trainees had higher overall rates of exertional hyponatremia diagnoses. Between 2007 and 2022, annual rates of incident exertional hyponatremia diagnoses peaked (12.7 per 100,000 p-yrs) in 2010 and then decreased to a low of 5.3 cases per 100,000 p-yrs in 2013. During the last 9 years of the surveillance period, rates fell between a range of 6.1 and 8.6 cases per 100,000 p-yrs. Service members and their supervisors must know the dangers of excessive water consumption and prescribed limits for water intake during prolonged physical activity, such as field training exercises, personal fitness training, as well as recreational activities, particularly in hot, humid weather.