Jones-Ngo Caitlin G, Schmidt Rebecca J, Monier Erwan, Ludwick Sara, Al-Hamdan Mohammad Z, Vargo Jason, Conlon Kathryn C
Department of Public Health Sciences University of California Davis CA USA.
Scripps Institution of Oceanography University of California San Diego CA USA.
Geohealth. 2025 Jun 6;9(6):e2024GH001237. doi: 10.1029/2024GH001237. eCollection 2025 Jun.
Wildfire smoke and extreme heat events are worsening in California, but their combined health effects are not well understood. This study estimates joint effects of extreme heat and wildfire smoke on hospitalizations in California, 2011-2020. We used a case crossover design with time-stratified controls and conditional logistic regression to estimate these effects at multiplicative and additive scales. Exposures were assessed for 16 combinations of exposure lags (0-3 days) for extreme heat and wildfire influenced fine particulate matter. Among over 28 million cases of all-natural cause morbidity, the majority were adults aged 65 and older (41.4%), English speakers (85.1%), and White, non-Hispanic (49.7%), mostly residing in urban areas (97.2%). The study found roughly 8% of respiratory morbidities (95% CI, 2.4%-13.8%) were attributable to the interaction of wildfire smoke and extreme heat. Significant joint effects were also observed for cardiovascular (5.5%) and renal morbidities (6.2%). Subgroup analyses revealed stronger effects: Respiratory (19.2%, 95% CI 6.5%-32.1%) and cerebrovascular morbidities (15.7%, 95% CI 4%-27.4%) were most pronounced in Black individuals; older adults (50-64 years) showed strong effects for renal morbidities (15.4%, 95% CI -1.6%-32.6%); and cardiovascular effects were highest among females (9.8%, 95% CI 2.9%-16.7%). Effects on all-natural cause morbidity were generally null. The interaction of wildfire smoke and extreme heat within a short exposure window (4 days) increases hospitalizations; highlighting the need for joint heat and wildfire smoke interventions that target populations at greater risk.
加利福尼亚州的野火烟雾和极端高温事件正在恶化，但其对健康的综合影响尚未得到充分了解。本研究估计了2011年至2020年极端高温和野火烟雾对加利福尼亚州住院情况的联合影响。我们采用了带有时间分层对照的病例交叉设计和条件逻辑回归，以在乘法和加法尺度上估计这些影响。针对极端高温和受野火影响的细颗粒物的16种暴露滞后组合（0至3天）评估了暴露情况。在超过2800万例所有自然原因发病病例中，大多数是65岁及以上的成年人（41.4%）、讲英语的人（85.1%）以及非西班牙裔白人（49.7%），他们大多居住在城市地区（97.2%）。研究发现，大约8%的呼吸道疾病（95%置信区间，2.4% - 13.8%）可归因于野火烟雾和极端高温的相互作用。心血管疾病（5.5%）和肾脏疾病（6.2%）也观察到了显著的联合影响。亚组分析显示出更强的影响：呼吸道疾病（19.2%，95%置信区间6.5% - 32.1%）和脑血管疾病（15.7%，95%置信区间4% - 27.4%）在黑人个体中最为明显；老年人（50至64岁）的肾脏疾病影响较强（15.4%，95%置信区间 - 1.6% - 32.6%）；心血管疾病影响在女性中最高（9.8%，95%置信区间2.9% - 16.7%）。对所有自然原因发病的影响通常不显著。在短暴露窗口（4天）内，野火烟雾和极端高温的相互作用会增加住院率；这突出表明需要针对高危人群采取联合的高温和野火烟雾干预措施。
