Background

Wildland fire smoke is a significant source of PM_2.5 pollution in the western United States, with varying chemical composition and toxicity depending on fire characteristics.

Methods

We analyzed emergency department and urgent care visits in the Reno/Sparks, Nevada region during fire seasons (July-September) from 2012 to 2019. Wildland fire smoke PM_2.5 concentrations were determined using a novel approach that combined EPA monitor data, atmospheric dispersion modeling, fire emissions inventories, and Bayesian time-series modeling to estimate daily fire-specific smoke PM_2.5 concentrations. Distributed lag models were used to estimate associations between total smoke PM_2.5 concentrations, as well as smoke PM_2.5 concentrations classified by fire intensity and fuel type, and daily counts of 11 cardiorespiratory visit outcome groups.

Results

We observed positive lag-specific associations between total smoke PM_2.5 concentrations (per 10 µg/m³ increase) and visits for asthma exacerbation (Lag 0 RR: 1.040; 95 %CI: 1.006, 1.075), cardiovascular disease (Lag 3 RR: 1.015; 95 % CI: 0.999, 1.032), and cardiac dysrhythmia (Lag 3 RR: 1.029; 95 % CI:1.012, 1.047). Elevated cumulative associations were also observed between total smoke PM_2.5 and asthma exacerbation (Lag 0–4 RR: 1.066; 95 % CI: 1.005, 1.131), unspecified respiratory disorder (Lag 0–6 RR: 1.046; 95 % CI 0.993, 1.103), and dysrhythmia (Lag 0–5 RR: 1.072; 95 % CI: 1.018, 1.129). Visits for asthma exacerbation and unspecified respiratory disorder were more strongly associated with smoke from high intensity fires, whereas visits for dysrhythmia were more associated with smoke from low intensity fires. By fuel type, forest fire smoke was most strongly associated with increased asthma exacerbation, and visits for dysrhythmia were most strongly associated with smoke from shrub/scrub fires.

Conclusions

This study provides novel evidence that wildland fire intensity and fuel type may influence the relationship between smoke exposure and specific health outcomes, with implications for public health messaging and land management strategies.

中文翻译：

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火灾特性对烟雾 PM2.5 暴露与急性心肺健康事件相关性的影响

  背景

野火烟雾是美国西部 PM _2.5 污染的重要来源，其化学成分和毒性因火灾特性而异。

  方法

我们分析了 2012 年至 2019 年火灾季节（7 月至 9 月）内华达州里诺/斯帕克斯地区的急诊科和紧急护理就诊情况。野火烟雾 PM _2.5 浓度是使用一种新颖的方法确定的，该方法结合了 EPA 监测数据、大气扩散模型、火灾排放清单和贝叶斯时间序列模型，以估计每日火灾特定的烟雾 PM _2.5 浓度。分布式滞后模型用于估计总烟雾 PM _2.5 浓度以及按火灾强度和燃料类型分类的烟雾 PM _2.5 浓度与 11 个心肺访问结果组的每日计数之间的关联。

  结果

我们观察到总烟雾 PM _2.5 浓度（每增加 10 μg/m ³ ）与哮喘发作 （Lag 0 RR： 1.040;95 % CI： 1.006， 1.075）、心血管疾病 （Lag 3 RR： 1.015;95 % CI： 0.999， 1.032） 和心律失常 （Lag 3 RR： 1.029;95 % CI：1.012， 1.047） 的就诊之间呈正滞后特异性关联。还观察到总烟雾 PM _2.5 与哮喘发作（滞后 0-4 RR：1.066;95 % CI：1.005、1.131）、未指明的呼吸系统疾病（滞后 0-6 RR：1.046;95 % CI 0.993、1.103）和心律失常（滞后 0-5 RR：1.072;95 % CI：1.018、1.129）之间的累积相关性升高。哮喘加重和未指明的呼吸系统疾病就诊与高强度火灾产生的烟雾更密切相关，而心律失常就诊与低强度火灾产生的烟雾更相关。按燃料类型划分，森林火灾烟雾与哮喘加重增加的相关性最强，心律失常就诊与灌木/灌木丛火灾产生的烟雾相关性最强。

  结论

这项研究提供了新的证据，表明野火强度和燃料类型可能会影响烟雾暴露与特定健康结果之间的关系，从而对公共卫生信息和土地管理策略产生影响。