BACKGROUND Wildfire events are increasing in prevalence in the western United States. Research has found mixed results on the degree to which exposure to wildfire smoke is associated with an increased risk of mortality. METHODS We tested for an association between exposure to wildfire smoke and non-traumatic mortality in Washington State, USA. We characterized wildfire smoke days as binary for grid cells based on daily average PM2.5 concentrations, from June 1 through September 30, 2006-2017. Wildfire smoke days were defined as all days with assigned monitor concentration above a PM2.5 value of 20.4 μg/m3, with an additional set of criteria applied to days between 9 and 20.4 μg/m3. We employed a case-crossover study design using conditional logistic regression and time-stratified referent sampling, controlling for humidex. RESULTS The odds of all-ages non-traumatic mortality with same-day exposure was 1.0% (95% CI: - 1.0 - 4.0%) greater on wildfire smoke days compared to non-wildfire smoke days, and the previous day's exposure was associated with a 2.0% (95% CI: 0.0-5.0%) increase. When stratified by cause of mortality, odds of same-day respiratory mortality increased by 9.0% (95% CI: 0.0-18.0%), while the odds of same-day COPD mortality increased by 14.0% (95% CI: 2.0-26.0%). In subgroup analyses, we observed a 35.0% (95% CI: 9.0-67.0%) increase in the odds of same-day respiratory mortality for adults ages 45-64. CONCLUSIONS This study suggests increased odds of mortality in the first few days following wildfire smoke exposure. It is the first to examine this relationship in Washington State and will help inform local and state risk communication efforts and decision-making during future wildfire smoke events.

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2006-2017年华盛顿州与野火烟雾接触相关的死亡率：病例交叉研究。

背景技术在美国西部，野火事件的发生率正在增加。研究发现，暴露于野火烟雾与死亡风险增加相关的结果好坏参半。方法我们测试了美国华盛顿州野火烟雾暴露与非创伤性死亡率之间的关联。根据2006-2017年6月1日至9月30日的每日平均PM2.5浓度，我们将野火烟雾天数作为网格单元的二值。野火烟雾天数被定义为监测器浓度高于20.4μg/ m3的PM2.5值的所有日子，并对9至20.4μg/ m3的天数应用了一组附加标准。我们采用了案例交叉研究设计，该研究使用条件逻辑回归和时间分层参考样本进行控制，以控制湿度。结果野火烟日与非野火烟日相比，全天同日暴露的非创伤性死亡的几率高1.0％（95％CI：-1.0-4.0％），并且前一天的暴露与增长了2.0％（95％CI：0.0-5.0％）。按死亡原因分层时，当日呼吸道疾病死亡率增加9.0％（95％CI：0.0-18.0％），而当日COPD死亡率增加14.0％（95％CI：2.0-26.0） ％）。在亚组分析中，我们观察到45-64岁成年人的当日呼吸道疾病死亡率增加35.0％（95％CI：9.0-67.0％）。结论这项研究表明，野火烟雾暴露后的头几天死亡率增加。