Background

Evidence of the adverse neurological effects of exposure to ambient air pollution is emerging, but little is known about its effect on the development of multiple sclerosis (MS), the most common autoimmune disease of the central nervous system.

Objectives

To investigate the associations between MS incidence and long-term exposures to fine particles (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃)

Methods

We conducted a population-based cohort study to investigate the associations between long-term exposures to PM_2.5, NO₂, and O₃ and the incidence of MS. Our study population included all Canadian-born residents aged 20–40 years who lived in the province of Ontario, Canada from 2001 to 2013. Incident MS was ascertained from a validated registry. We assigned estimates of annual concentrations of these pollutants to the residential postal codes of subjects for each year during the 13 years of follow-up. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for each pollutant separately using random-effects Cox proportional hazards models. We conducted various sensitivity analyses, such as lagging exposure up to 5 years and adjusting for access to neurological care, annual average temperature, and population density.

Results

Between 2001 and 2013, we identified 6203 incident cases of MS. The adjusted HR of incident MS was 0.96 (95% CI: 0.86–1.07) for PM_2.5, 0.91(95% CI: 0.81–1.02) for NO₂, and 1.09 (95% CI: 0.98–1.23) for O₃. These results were robust to various sensitivity analyses conducted.

Conclusions

In this large population-based cohort, we did not observe significant associations between MS incidence and long-term exposures to PM_2.5, NO₂, and O₃ in adults in Ontario, 2001–2013.

中文翻译：

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长期暴露于空气污染和多发性硬化症的发病率：一项基于人群的队列研究

背景

暴露于环境空气污染对神经系统的不利影响的证据不断涌现，但人们对其对多发性硬化症（MS）的发展所知甚少，多发性硬化症是中枢神经系统最常见的自身免疫性疾病。

目标

调查MS发病率与长期暴露于细颗粒（PM _2.5），二氧化氮（NO ₂）和臭氧（O ₃）之间的关联

方法

我们进行了一项基于人群的队列研究，以调查长期暴露于PM _2.5，NO ₂和O _{3之间的关系}和MS的发生率。我们的研究人群包括所有2001年至2013年在加拿大安大略省居住的20至40岁的加拿大出生居民。在随访的13年中，我们将这些污染物的年度浓度估算值分配给了受试者的住宅邮政编码。我们使用随机效应Cox比例风险模型分别估算了每种污染物的危害比（HRs）和95％置信区间（CIs）。我们进行了各种敏感性分析，例如滞后时间长达5年，并针对获得神经科护理，年平均温度和人口密度进行了调整。

结果

在2001年至2013年之间，我们确定了6203例MS事件。PM _2.5的入射MS校正后HR为0.96（95％CI：0.86-1.07 ），NO ₂为0.91 （95％CI：0.81-1.02），O ₃为1.09（95％CI：0.98-1.23）。这些结果对于所进行的各种敏感性分析是可靠的。

结论

在这个以人口为基础的大队列中，我们没有观察到2001-2013年安大略省成年人的MS发病率与长期暴露于PM _2.5，NO ₂和O _3的显着相关性。