ABSTRACT

Smoke from burning biomass is an important source of fine particulate matter (PM_2.5), but the health risks may not be fully captured by the Canadian Air Quality Health Index (AQHI). In May 2018, the province of British Columbia launched an evidence-based amendment (AQHI-Plus) to improve AQHI performance for wildfire smoke, but the AQHI-Plus was not developed or tested on data from the residential woodsmoke season. This study assesses how the AQHI and AQHI-Plus are associated with acute health outcomes during the cooler seasons of 2010–2017 in British Columbia, Canada. Monthly and daily patterns of temperature and PM_2.5 concentrations were used to identify Local Health Areas (LHAs) that were impacted by residential woodsmoke. The effects of the AQHI and AQHI-Plus on five acute health outcomes (including non-accidental mortality, outpatient physician visits, and medical dispensations for cardiopulmonary conditions) were estimated using generalized linear mixed effect models with Poisson distributions adjusted for long- and short-term temperature trends. Values of the Akaike information criterion (AIC) were compared to evaluate whether the AQHI or AQHI-Plus was better fitted to each health outcome. Eleven LHAs were categorized as woodsmoke-impacted. In these LHAs, the AQHI and AQHI-Plus associations with acute health outcomes were sensitive to temperature adjustments. After temperature adjustments, the most consistent associations were observed for the two asthma-specific outcomes where the AQHI-Plus was better fitted than the AQHI. The improved performance of the AQHI-Plus for susceptible populations with asthma is consistent between communities impacted by residential woodsmoke and wildfire smoke.

Implications: Canada’s Air Quality Health Index (AQHI) is a three pollutant index used to communicate the short term health impact of degraded air quality. As fine particulate matter (PM_2.5) is the lowest weighted pollutant in the AQHI, the index is poorly reflective of woodsmoke impacts. The present analysis found that an AQHI amendment developed for improved sensitivity to PM_2.5 during wildfire seasons (AQHI-Plus) is also more predictive of acute asthma-related health outcomes in communities impacted by residential woodsmoke. The BC Ministry of Environment and Climate Change Strategy has piloted the AQHI-Plus year-round. Other jurisdictions should consider whether their air quality indices are reflective of the risks posed by woodsmoke.

摘要

生物质燃烧产生的烟雾是细颗粒物（PM _2.5）的重要来源，但是加拿大空气质量健康指数（AQHI）可能无法完全捕捉健康风险。2018年5月，不列颠哥伦比亚省发起了一项基于证据的修正案（AQHI-Plus），以改善野火烟雾的AQHI性能，但AQHI-Plus并未针对民用木烟季节的数据进行开发或测试。这项研究评估了在加拿大不列颠哥伦比亚省2010-2017年较冷的季节中，AQHI和AQHI-Plus与急性健康结果之间的关系。每月和每天的温度和PM _2.5模式浓度可用于识别受住宅烟熏影响的当地卫生区（LHA）。使用广义线性混合效应模型估计了AQHI和AQHI-Plus对五种急性健康结局（包括非意外死亡，门诊就诊以及心肺疾病的医疗分配）的影响，并根据泊松分布对长期和短期影响进行了调整长期温度趋势。比较了Akaike信息标准（AIC）的值，以评估AQHI或AQHI-Plus是否更适合每种健康状况。11个LHA被归类为受烟熏影响。在这些LHA中，具有急性健康结果的AQHI和AQHI-Plus协会对温度调节敏感。调整温度后，在两种特定于哮喘的结局中观察到最一致的关联，其中AQHI-Plus比AQHI更适合。AQHI-Plus对易感哮喘人群的改善性能在居住烟熏和野火烟气影响的社区之间是一致的。

潜在影响：加拿大的空气质量健康指数（AQHI）是三种污染物指数，用于传达空气质量下降对健康的短期影响。由于细颗粒物（PM _2.5）是AQHI中加权最低的污染物，因此该指数不能很好地反映木烟的影响。本分析发现，为提高野火季节对PM _2.5的敏感性而开发的AQHI修正案（AQHI-Plus）也更能预测受木烟影响的社区与哮喘相关的急性健康后果。卑诗省环境与气候变化战略部全年对AQHI-Plus进行了试点。其他辖区应考虑其空气质量指数是否反映了烟熏所带来的风险。