Evidence map›Paper›PMID 41790999›Full record

ArticleEpidemiology (Cambridge, Mass.)2026

Spatial Heterogeneity in Synergistic Effects of Extreme Heat and NO 2 Exposures on Cardiorespiratory Hospitalizations in California.

Yiqun Ma, Chen Chen, Rosana Aguilera, Alexander Gershunov, Michael Jerrett, Rachel Connolly, Miriam E Marlier, Tarik Benmarhnia

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Article in Epidemiology (Cambridge, Mass.), 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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2 · The registry

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3 · Its place in the literature

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4 · The record

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5 · Who and what money

Authors and funding

8 authors.

Yiqun MaFrom the Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA.ORCID 0000-0001-5000-5756
Chen ChenFrom the Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA.
Rosana AguileraFrom the Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA.
Alexander GershunovFrom the Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA.
Michael JerrettDepartment of Environmental Health Sciences, Fielding School of Public Health, University of California Los Angeles, Los Angeles, CA.
Rachel ConnollyDepartment of Environmental Health Sciences, Fielding School of Public Health, University of California Los Angeles, Los Angeles, CA.
Miriam E MarlierDepartment of Environmental Health Sciences, Fielding School of Public Health, University of California Los Angeles, Los Angeles, CA.
Tarik BenmarhniaFrom the Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundExtreme heat and high air pollution levels may co-occur and act synergistically. The synergistic health effects of extreme heat and nitrogen dioxide (NO 2 ) , and the fine-scale spatial heterogeneity in such joint effects, remain unclear. We aimed to investigate the synergistic effect of extreme heat and NO 2 exposures on cardiorespiratory hospitalizations in California and explore its spatial heterogeneity.

methodsDaily ZIP Code Tabulation Area (ZCTA)-level hospitalization data, 2000-2019, were obtained from the California Department of Health Care Access and Information. Extreme heat and NO 2 exposures were defined as days when the heat index and NO 2 concentration exceeded a ZCTA-specific threshold, respectively. We first investigated the state-level synergistic effects with a case-crossover analysis and then estimated the ZCTA-specific synergistic effects using a within-community matched design combined with a spatial Bayesian hierarchical model. Finally, we explored how community characteristics modify these effects using meta-regressions.

resultsWe found mild synergistic effects of extreme heat and NO 2 exposures on cardiorespiratory hospitalizations at the state level, with a relative excess risk due to interaction (RERI) of 0.005 (95% confidence interval = -0.002, 0.011). Yet, great spatial heterogeneity was observed, with ZCTA-specific RERIs ranging from -1.08 to 2.22. Higher RERIs were observed in communities with lower socioeconomic status, higher population density, reduced green space, greater proportions of racial and ethnic minority residents, and higher historical temperatures.

conclusionsOur findings underscore the need for adaptation policies that integrate compound exposures to heat and air pollution and inform the development of targeted intervention strategies to protect vulnerable communities.

Indexed as

Air PollutionCardiovascular DiseasesEnvironmental ExposureExtreme HeatHospitalizationNitrogen DioxideCaliforniaHumansSpatial AnalysisNitrogen DioxideAir pollutionCardiorespiratory hospitalizationsEnvironmental justiceExtreme heatNitrogen dioxideSynergistic effects

Identifiers

PMID41790999
PMCPMC13218587

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.