{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T16:53:23Z","timestamp":1787072003399,"version":"build-2736575974"},"reference-count":22,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T00:00:00Z","timestamp":1787011200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Int. J. Environ. Res. Public Health","IJERPH"],"abstract":"<jats:p>Future climate projections suggest an increase in heat-related mortality and a decrease in cold-related deaths under warming scenarios. Understanding the health impacts of extreme heat, and their implications for healthcare demand is essential for assessing the future burden of climate-related illnesses. In this study, we examined the relationship between extreme heat events and Emergency Department Visits (EDV) for heat-related illnesses (HRIs) across the United States from 2018 to 2025. Using data from the Centers for Disease Control and Prevention (CDC) Heat and Health Tracker and other relevant sources, we analyzed EDV rates standardized to 100,000 population. We aggregated daily into the 10 U.S. Health and Human Services (HHS) Regions. We used 0.5\u00b0 \u00d7 0.5\u00b0 gridded maximum daily temperature data (aggregated to HHS regions with proportional area weighting) and daily maximum heat index extracted from the CDC data portal (estimated using the US National Weather Service methodology and aggregated to HHS regions using total population weighting) to characterize seasonal patterns and regional variability. The association between peak heat events and EDV time series was explored using log-linear mixed-effects models, which accounted for seasonal trends, climate variables, and their regional variability. Random effects were used to capture regional heterogeneity in predictor-response relationships, accommodating variation in associations across regions. Model performance was evaluated using prediction error metrics and goodness-of-fit assessments. Maximum temperature and heat index were both significant predictors, with the heat index offering a slightly better fit. Associations were largely contemporaneous, with peak correlations at lag zero, underscoring the need for real-time response. EDV increased several days before peak environmental conditions, consistent with early exposure effects. While temperature-EDV relationships varied regionally, heat index associations were more stable. This work underscores the urgent need for regionally adaptive public health strategies in the face of intensifying climate extremes and outlines future directions for research and policy to strengthen health systems\u2019 preparedness in a warming world.<\/jats:p>","DOI":"10.3390\/ijerph23081074","type":"journal-article","created":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T16:12:11Z","timestamp":1787069531000},"page":"1074","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Extreme Heat and Emergency Health Impacts in the US (2018\u20132025)"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-7565-9232","authenticated-orcid":false,"given":"Tyler","family":"Hecht","sequence":"first","affiliation":[{"name":"Department of Statistics, University of Illinois Urbana-Champaign; Champaign, IL 61820, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Baoyuan","family":"Zhou","sequence":"additional","affiliation":[{"name":"Department of Statistics, University of Illinois Urbana-Champaign; Champaign, IL 61820, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-0225-0154","authenticated-orcid":false,"given":"Abhi","family":"Thanvi","sequence":"additional","affiliation":[{"name":"Department of Statistics, University of Illinois Urbana-Champaign; Champaign, IL 61820, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0742-663X","authenticated-orcid":false,"given":"Lelys Bravo de","family":"Guenni","sequence":"additional","affiliation":[{"name":"Department of Statistics, University of Illinois Urbana-Champaign; Champaign, IL 61820, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,18]]},"reference":[{"key":"ref_1","unstructured":"National Oceanic and Atmospheric Administration (NOAA) (2026, February 28). Summary of Natural Hazard Statistics for 2024 in the United States, Available online: https:\/\/www.weather.gov\/media\/hazstat\/sum24.pdf."},{"key":"ref_2","unstructured":"Statista (2026, August 10). The World\u2019s Record Heatwaves. Available online: https:\/\/www.statista.com\/chart\/27403\/global-heat-waves\/."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1796","DOI":"10.1038\/s41467-024-45901-z","article-title":"Impact of population aging on future temperature-related mortality at different global warming levels","volume":"15","author":"Chen","year":"2024","journal-title":"Nat. Commun."},{"key":"ref_4","unstructured":"Climate Impact Lab, and United Nations Development Programme (UNDP) (2026, August 10). Changing Climate Will Exacerbate Global Inequalities in Health, Energy, and Labor Impacts. Available online: https:\/\/impactlab.org\/news-insights\/global-inequalities-humanclimatehorizons-undp\/."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Thiel, J., Seim, A., Stephan, B., Sedlmayr, M., Prochaska, E., and Henke, E. (2025). The Spectrum of Heat-Related Diseases: A Meta-Review. Int. J. Public Health, 70.","DOI":"10.3389\/ijph.2025.1608592"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"324","DOI":"10.15585\/mmwr.mm7315a1","article-title":"Heat-Related Emergency Department Visits\u2014United States, May\u2013September 2023","volume":"73","author":"Vaidyanathan","year":"2024","journal-title":"Morb. Mortal. Wkly. Rep."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Narayanan, A., and Keellings, D. (2025). Rise in heat related mortality in the United States. PLoS Clim., 4.","DOI":"10.31223\/X5114K"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"101432","DOI":"10.1016\/j.lanplh.2026.101432","article-title":"Heat waves and annual mortality among older adults (aged \u226565 years) in the USA","volume":"10","author":"Healy","year":"2026","journal-title":"Lancet Planet. Health"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1111","DOI":"10.1289\/ehp.1206273","article-title":"Methods to Calculate the Heat Index as an Exposure Metric in Environmental Health Research","volume":"121","author":"Anderson","year":"2013","journal-title":"Environ. Health Perspect."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"720","DOI":"10.1175\/JCLI-D-13-00159.1","article-title":"Quantifying the Strength and Delay of Climatic Interactions: The Ambiguities of Cross Correlation and a Novel Measure Based on Graphical Models","volume":"27","author":"Runge","year":"2014","journal-title":"J. Clim."},{"key":"ref_11","first-page":"3","article-title":"STL: A Seasonal-Trend Decomposition Procedure Based on Loess","volume":"6","author":"Cleveland","year":"1990","journal-title":"J. Off. Stat."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"S82","DOI":"10.1111\/insr.12529","article-title":"Global seasonal and pandemic patterns in influenza: An application of longitudinal study designs","volume":"90","author":"Naumova","year":"2022","journal-title":"Int. Stat. Rev."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Feng, C., Li, L., and Sadeghpour, A. (2020). A comparison of residual diagnosis tools for diagnosing regression models for count data. BMC Med. Res. Methodol., 20.","DOI":"10.1186\/s12874-020-01055-2"},{"key":"ref_14","unstructured":"Hartig, F. (2026, June 30). DHARMa: Residual Diagnostics for Hierarchical (Multi-Level\/Mixed) Regression Models [Computer Software Manual]. R package version 0.4.7. Available online: http:\/\/florianhartig.github.io\/DHARMa\/."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1186\/1476-069X-13-89","article-title":"Acclimatization across space and time in the effects of temperature on mortality: A time-series analysis","volume":"13","author":"Lee","year":"2014","journal-title":"Environ. Health"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"39581","DOI":"10.1038\/srep39581","article-title":"Heat-Related Hospitalizations in Older Adults: An Amplified Effect of the First Seasonal Heatwave","volume":"7","author":"Liss","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"5420","DOI":"10.1073\/pnas.1806393116","article-title":"Assessment of extreme heat and hospitalizations to inform early warning systems","volume":"116","author":"Vaidyanathan","year":"2019","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1187","DOI":"10.1289\/ehp.1206132","article-title":"Heat, heat waves, and hospital admissions among the elderly in the United States, 1992\u20132006","volume":"122","author":"Gronlund","year":"2014","journal-title":"Environ. Health Perspect."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1186\/s12940-026-01289-5","article-title":"Mapping heat-related morbidity burden attributable to human-induced climate change across 460 communities of Victoria, Australia","volume":"25","author":"Xing","year":"2026","journal-title":"Environ. Health"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"e065653","DOI":"10.1136\/bmj-2021-065653","article-title":"Ambient heat and risks of emergency department visits among adults in the United States: Time stratified case crossover study","volume":"375","author":"Sun","year":"2021","journal-title":"BMJ"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1338","DOI":"10.5811\/WESTJEM.42263","article-title":"Impact of Daily Maximum Temperature on Emergency Department Arrivals and Acuity Levels","volume":"26","author":"Giudice","year":"2025","journal-title":"West. J. Emerg. Med."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e245134","DOI":"10.1001\/jamahealthforum.2024.5134","article-title":"Regional Variability of Extreme Heat and Cold Risk Among Dual-Eligible Individuals","volume":"6","author":"Yoo","year":"2025","journal-title":"JAMA Health Forum"}],"container-title":["International Journal of Environmental Research and Public Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1660-4601\/23\/8\/1074\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T16:13:55Z","timestamp":1787069635000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1660-4601\/23\/8\/1074"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,18]]},"references-count":22,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["ijerph23081074"],"URL":"https:\/\/doi.org\/10.3390\/ijerph23081074","relation":{},"ISSN":["1660-4601"],"issn-type":[{"value":"1660-4601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,18]]}}}