Background Long-term exposure to traffic-borne noise and air pollution has been variably associated with incidence of acute vascular events, namely acute myocardial infarction, ischaemic stroke and haemorrhagic stroke. This study aims at exploring this association within a highly urbanized city. Methods This is a population-based retrospective dynamic cohort study including all residents aged ≥ 35 years in the municipality of Milan over the years 2011–18 (1 087 110 inhabitants). Residential exposure to road traffic noise (day-evening-night levels) and nitrogen dioxide was estimated using a noise predictive model and a land use regression model, respectively. Cox proportional hazards regression analyses were performed to assess the incidence of acute vascular events and specific outcomes in single-exposure and two-exposure models including adjustment for sociodemographic confounders, fine particulate matter and surrounding greenness. Results A total of 27 282 subjects (2.5%) had an acute vascular event. Models using nitrogen dioxide produced inconsistent results. The strongest effect was observed for noise, with an optimal cut-off for dichotomization set at 70 dBA (hazard ratio 1.025, 95% confidence interval 1.000–1.050). This association was observed specifically for ischaemic and haemorrhagic stroke. When stratifying by age group and sex, a remarkable effect was found for haemorrhagic stroke in men aged <60 years (hazard ratio 1.439, 95% confidence interval 1.156–1.792). Conclusions Living by roads with a day-evening-night noise level above 70 dBA exerts a small but tangible independent effect on the risks of both ischaemic and haemorrhagic stroke. It is urgent to propose mitigation measures against pollution and noise originating from vehicular traffic in order to reduce their impact, especially in the population younger than 60 years.

中文翻译：

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居民暴露于交通污染是急性心脑血管事件的危险因素：在高度城市化地区进行的基于人群的回顾性队列研究

背景 长期暴露于交通噪声和空气污染与急性血管事件的发生率不同，即急性心肌梗塞、缺血性中风和出血性中风。本研究旨在探索高度城市化城市中的这种关联。方法 这是一项基于人群的回顾性动态队列研究，包括 2011-18 年间米兰市所有年龄 ≥ 35 岁的居民（1 087 110 名居民）。分别使用噪声预测模型和土地利用回归模型估计住宅暴露于道路交通噪声（昼夜水平）和二氧化氮。进行 Cox 比例风险回归分析以评估单次暴露和两次暴露模型中急性血管事件的发生率和特定结果，包括对社会人口学混杂因素、细颗粒物和周围绿色度的调整。结果共有27 282名受试者（2.5%）发生了急性血管事件。使用二氧化氮的模型产生的结果不一致。观察到对噪声的影响最强，二分法的最佳截止值设置为 70 dBA（风险比 1.025，95% 置信区间 1.000-1.050）。这种关联是专门针对缺血性和出血性中风观察到的。当按年龄组和性别分层时，发现对年龄 <60 岁男性的出血性中风有显着影响（风险比 1.439，95% 置信区间 1.156-1.792）。结论 生活在昼夜噪声水平高于 70 分贝的道路上，对缺血性和出血性中风的风险产生微小但明显的独立影响。迫切需要针对来自车辆交通的污染和噪音提出缓解措施，以减少其影响，尤其是对 60 岁以下人群的影响。