Abstract

Background:

Mounting evidence has shown that long-term exposure to fine particulate matter [PM $\le 2.5\mathrm{\mu }\mathrm{m}$ in aerodynamic diameter (${\mathrm{PM}}_{2.5}$)] and ozone (${\mathrm{O}}_3$) can increase mortality. However, the health effects associated with long-term exposure to nitrogen dioxide (${\mathrm{NO}}_2$) are less clear, in particular the evidence is scarce for ${\mathrm{NO}}_2$ at low levels that are below the current international guidelines.

Methods:

We constructed a population-based full cohort comprising all Medicare beneficiaries (aged $\ge 65$, $N=\mathrm{13,590,387}$) in the southeastern United States from 2000 to 2016, and we then further defined the below-guideline cohort that included only those who were always exposed to low-level ${\mathrm{NO}}_2$, that is, with annual means below the current World Health Organization guidelines (i.e., $\le 21\text{\hspace{0.17em}ppb}$). We applied previously estimated spatially and temporally resolved ${\mathrm{NO}}_2$ concentrations and assigned annual means to study participants based on their ZIP code of residence. Cox proportional hazards models were used to examine the association between long-term exposure to low-level ${\mathrm{NO}}_2$ and all-cause mortality, adjusting for potential confounders.

Results:

About 71.1% of the Medicare beneficiaries in the southeastern United States were always exposed to low-level ${\mathrm{NO}}_2$ over the study period. We observed an association between long-term exposure to low-level ${\mathrm{NO}}_2$ and all-cause mortality, with a $\text{hazard ratio\hspace{0.17em}}\left(\text{HR}\right)=$ 1.042 (95% CI: 1.040, 1.045) in single-pollutant models and a $\text{HR}=$ 1.047 (95% CI: 1.045, 1.049) in multipollutant models (adjusting for ${\mathrm{PM}}_{2.5}$ and ${\mathrm{O}}_3$), per $10\text{-ppb}$ increase in annual ${\mathrm{NO}}_2$ concentrations. The penalized spline indicates a linear exposure–response relationship across the entire ${\mathrm{NO}}_2$ exposure range. Medicare enrollees who were White, female, and residing in urban areas were more vulnerable to long-term ${\mathrm{NO}}_2$ exposure.

Conclusion:

Using a large and representative cohort, we provide epidemiological evidence that long-term exposure to ${\mathrm{NO}}_2$, even below the national and global ambient air quality guidelines, was approximately linearly associated with a higher risk of mortality among older adults, independent of ${\mathrm{PM}}_{2.5}$ and ${\mathrm{O}}_3$ exposure. Improving air quality by reducing ${\mathrm{NO}}_2$ emissions, therefore, may yield significant health benefits. https://doi.org/10.1289/EHP9044

中文翻译：

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美国东南部老年人口长期暴露于低水平二氧化氮和死亡率

摘要

背景：

越来越多的证据表明，长期暴露于细颗粒物 [PM$\le 2.5\mathrm{\mu }\mathrm{米}$气动直径 (${\mathrm{下午}}_{2.5}$)] 和臭氧 (${\mathrm{○}}_3$) 会增加死亡率。然而，与长期接触二氧化氮相关的健康影响（${\mathrm{不}}_2$) 不太清楚，特别是缺乏证据${\mathrm{不}}_2$低于当前国际准则的低水平。

方法：

我们构建了一个基于人群的完整队列，包括所有医疗保险受益人（老年$\ge 65$,$ñ=\mathrm{13,590,387}$) 于 2000 年至 2016 年在美国东南部，然后我们进一步定义了低于指南的队列，仅包括那些始终暴露于低水平${\mathrm{不}}_2$，也就是说，年均值低于当前的世界卫生组织指南（即，$\le 21\text{\hspace{0.17em}ppb}$）。我们应用了先前估计的空间和时间分辨${\mathrm{不}}_2$浓度和分配的年度手段，根据他们的居住邮政编码研究参与者。Cox 比例风险模型用于检查长期暴露于低水平${\mathrm{不}}_2$和全因死亡率，调整潜在的混杂因素。

结果：

美国东南部约 71.1% 的医疗保险受益人始终暴露于低水平${\mathrm{不}}_2$在学习期间。我们观察到长期暴露于低水平${\mathrm{不}}_2$和全因死亡率，$\text{危险几率\hspace{0.17em}}\left(\text{人力资源}\right)=$1.042 (95% CI: 1.040, 1.045) 在单一污染物模型和$\text{人力资源}=$多污染物模型中的 1.047 (95% CI: 1.045, 1.049)（调整为${\mathrm{下午}}_{2.5}$和${\mathrm{○}}_3$), 每$10\text{-ppb}$每年增加${\mathrm{不}}_2$浓度。惩罚样条表示整个整体的线性曝光 - 响应关系${\mathrm{不}}_2$曝光范围。居住在城市地区的白人、女性和医疗保险参保者更容易受到长期${\mathrm{不}}_2$接触。

结论：

使用大型且具有代表性的队列，我们​​提供了流行病学证据表明长期接触${\mathrm{不}}_2$，即使低于国家和全球环境空气质量指南，也与老年人死亡率较高的风险大致呈线性相关，独立于${\mathrm{下午}}_{2.5}$和${\mathrm{○}}_3$接触。通过减少空气质量来改善${\mathrm{不}}_2$因此，排放可能会产生显着的健康益处。https://doi.org/10.1289/EHP9044