Objective To investigate the association between changes in long term residential exposure to ambient fine particulate matter (PM2.5) and premature mortality in Canada. Design Population based quasi-experimental study. Setting Canada. Participants 663 100 respondents to the 1996, 2001, and 2006 Canadian censuses aged 25-89 years who had consistently lived in areas with either high or low PM2.5 levels over five years preceding census day and moved during the ensuing five years. Interventions Changes in long term exposure to PM2.5 arising from residential mobility. Main outcome measures The primary outcome was deaths from natural causes. Secondary outcomes were deaths from any cardiometabolic cause, any respiratory cause, and any cancer cause. All outcomes were obtained from the national vital statistics database. Results Using a propensity score matching technique with numerous personal, socioeconomic, health, and environment related covariates, each participant who moved to a different PM2.5 area was matched with up to three participants who moved within the same PM2.5 area. In the matched groups that moved from high to intermediate or low PM2.5 areas, residential mobility was associated with a decline in annual PM2.5 exposure from 10.6 μg/m3 to 7.4 and 5.0 μg/m3, respectively. Conversely, in the matched groups that moved from low to intermediate or high PM2.5 areas, annual PM2.5 increased from 4.6 μg/m3 to 6.7 and 9.2 μg/m3. Five years after moving, individuals who experienced a reduction in exposure to PM2.5 from high to intermediate levels showed a 6.8% (95% confidence interval 1.7% to 11.7%) reduction in mortality (2510 deaths in 56 025 v 4925 deaths in 101 960). A greater decline in mortality occurred among those exposed to a larger reduction in PM2.5. Increased mortality was found with exposure to PM2.5 from low to high levels, and to a lesser degree from low to intermediate levels. Furthermore, the decreases in PM2.5 exposure were most strongly associated with reductions in cardiometabolic deaths, whereas the increases in PM2.5 exposure were mostly related to respiratory deaths. No strong evidence was found for the changes in PM2.5 exposure with cancer related deaths. Conclusions In Canada, decreases in PM2.5 were associated with lower mortality, whereas increases in PM2.5 were associated with higher mortality. These results were observed at PM2.5 levels considerably lower than many other countries, providing support for continuously improving air quality. Statistics Canada’s policy on data privacy and confidentiality prohibits the analytical cohorts used (1996, 2001, and 2006 CanCHEC) to be freely available in the manuscript, supplementary files, or in a public repository. However, access can be granted through Statistics Canada’s Research Data Centre program. The programs used to assign environmental exposures (PCCF+ and postal code imputation) are also available to researchers through subscription or request. Environmental exposures are available on request to the original authors of the data. The analytical code used was all standard R and SAS code (eg, matchit, mice, glm, coxph, data steps).

中文翻译：

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加拿大搬迁和长期生存后环境细颗粒物暴露的变化：准实验研究

目的 调查加拿大居民长期暴露于环境细颗粒物 (PM2.5) 的变化与过早死亡之间的关联。设计基于人群的准实验研究。设置加拿大。参与者 663 100 名 1996、2001 和 2006 年加拿大人口普查的受访者，年龄在 25-89 岁之间，他们在人口普查日之前的五年内一直居住在 PM2.5 水平高或低的地区，并在随后的五年中搬家。干预措施 居民流动引起的 PM2.5 长期暴露的变化。主要结局指标 主要结局是自然原因造成的死亡。次要结果是任何心脏代谢原因、任何呼吸系统原因和任何癌症原因造成的死亡。所有结果均来自国家生命统计数据库。结果 使用倾向评分匹配技术与众多个人、社会经济、健康和环境相关的协变量，将每个搬到不同 PM2.5 区域的参与者与在同一 PM2.5 区域内移动的最多三名参与者进行匹配。在从高 PM2.5 区域移动到中等或低 PM2.5 区域的匹配组中，居民流动性与年度 PM2.5 暴露量分别从 10.6 μg/m3 下降到 7.4 和 5.0 μg/m3 相关。相反，在从低 PM2.5 区域移动到中等或高 PM2.5 区域的匹配组中，年 PM2.5 从 4.6 μg/m3 增加到 6.7 和 9.2 μg/m3。搬家五年后，PM2.5 暴露水平从高到中减少的个体表现出 6.8%（95% 置信区间为 1.7% 到 11.5%）。7%) 死亡率降低（56025 人中有 2510 人死亡，101960 人中有 4925 人死亡）。PM2.5 下降幅度更大的人群死亡率下降幅度更大。PM2.5 从低水平到高水平暴露于PM2.5，从低到中水平暴露程度较低，死亡率增加。此外，PM2.5 暴露的减少与心脏代谢死亡的减少最密切相关，而 PM2.5 暴露的增加主要与呼吸系统死亡有关。没有发现强有力的证据表明 PM2.5 暴露的变化与癌症相关的死亡有关。结论 在加拿大，PM2.5 的降低与较低的死亡率相关，而 PM2.5 的增加与较高的死亡率相关。这些结果是在 PM2.5 水平明显低于许多其他国家的情况下观察到的，为持续改善空气质量提供支持。加拿大统计局关于数据隐私和保密的政策禁止使用的分析队列（1996、2001 和 2006 CanCHEC）在手稿、补充文件或公共存储库中免费提供。但是，可以通过加拿大统计局的研究数据中心计划授予访问权限。用于分配环境暴露的程序（PCCF+ 和邮政编码估算）也可通过订阅或请求提供给研究人员。环境暴露可应要求提供给数据的原始作者。使用的分析代码都是标准的 R 和 SAS 代码（例如，matchit、mice、glm、coxph、数据步骤）。和 2006 CanCHEC) 在手稿、补充文件或公共存储库中免费提供。但是，可以通过加拿大统计局的研究数据中心计划授予访问权限。用于分配环境暴露的程序（PCCF+ 和邮政编码估算）也可通过订阅或请求提供给研究人员。环境暴露可应要求提供给数据的原始作者。使用的分析代码都是标准的 R 和 SAS 代码（例如，matchit、mice、glm、coxph、数据步骤）。和 2006 CanCHEC) 在手稿、补充文件或公共存储库中免费提供。但是，可以通过加拿大统计局的研究数据中心计划授予访问权限。用于分配环境暴露的程序（PCCF+ 和邮政编码估算）也可通过订阅或请求提供给研究人员。环境暴露可应要求提供给数据的原始作者。使用的分析代码都是标准的 R 和 SAS 代码（例如，matchit、mice、glm、coxph、数据步骤）。用于分配环境暴露的程序（PCCF+ 和邮政编码估算）也可通过订阅或请求提供给研究人员。环境暴露可应要求提供给数据的原始作者。使用的分析代码都是标准的 R 和 SAS 代码（例如，matchit、mice、glm、coxph、数据步骤）。用于分配环境暴露的程序（PCCF+ 和邮政编码估算）也可通过订阅或请求提供给研究人员。环境暴露可应要求提供给数据的原始作者。使用的分析代码都是标准的 R 和 SAS 代码（例如，matchit、mice、glm、coxph、数据步骤）。