School of Public Health, Key Lab of Public Health Safety of the Ministry of Education and National Health Commission Key Lab of Health Technology Assessment, Fudan University, Shanghai, China.
National Center for Chronic and Noncommunicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
Lancet Planet Health. 2022 Jun;6(6):e496-e503. doi: 10.1016/S2542-5196(22)00093-6.
The evidence for a causal relationship between long-term ozone exposure and cardiovascular mortality is inconclusive, and most published data are from high-income countries. We aimed to investigate the association between long-term exposure to ozone and cardiovascular mortality in China, the most populous middle-income country.
We did a nationwide cohort study comprising Chinese adults aged 18 years and older from the 2010-11 China Chronic Disease and Risk Factors Surveillance project; participants were followed up until Dec 31, 2018, or the date of death. Data on participants' deaths were obtained through linkage to the Disease Surveillance Point system, a national death registration database. Residential ozone exposure was estimated with a previously developed random forest model. We applied stratified Cox proportional hazards models to estimate the associations of ozone with mortality due to overall cardiovascular diseases, ischaemic heart disease, and stroke. The models were stratified by age and sex and adjusted for a set of individual-level and regional covariates. Warm-season average ozone concentration for the previous 1-3 years was added as a time-varying variable. We also did subgroup analyses by age, sex, level of education, smoking status, urban or rural residence, and geographical region.
Data were analysed for 96 955 participants. The warm-season average ozone concentration during the follow-up period was 89·7 μg/m (SD 14·4). In the fully adjusted models, we observed significant and positive associations between ozone and mortality from overall cardiovascular diseases (hazard ratio [HR] 1·093 [95% CI 1·046-1·142] per 10 μg/m increase in warm-season ozone concentrations), ischaemic heart disease (1·184 [1·099-1·276] per 10 μg/m increase in warm-season ozone concentrations), and stroke (1·063 [1·002- 1·128] per 10 μg/m increase in warm-season ozone concentrations). After adjusting for fine particulate matter, the associations with overall cardiovascular disease and ischaemic heart disease mortality were almost unchanged, whereas the association with stroke mortality lost statistical significance. The association of long-term ozone exposure with cardiovascular mortality was more prominent in people aged 65 years and older than in those younger than 65 years. We did not find any effect modification of sex, level of education, smoking status, urban or rural residence, and geographical region. We observed an almost linear exposure-response relationship between ozone and cardiovascular mortality.
This study is, to the best of our knowledge, the first nationwide cohort study to show that long-term ozone exposure contributes to elevated risks of cardiovascular mortality, particularly from ischaemic heart disease, in a middle-income setting. The exposure-response function generated from this study could potentially inform future air quality standard revisions and environmental health impact assessments.
National Natural Science Foundation of China.
长期臭氧暴露与心血管死亡率之间存在因果关系的证据尚无定论，且大多数已发表的数据来自高收入国家。我们旨在研究长期暴露于臭氧与中国（人口最多的中等收入国家）心血管死亡率之间的关系。
我们进行了一项全国性的队列研究，纳入了来自 2010-11 年中国慢性病和危险因素监测项目的 18 岁及以上的中国成年人；参与者的随访时间截至 2018 年 12 月 31 日或死亡日期。通过与疾病监测点系统（一个全国性的死亡登记数据库）的链接，获得参与者死亡的数据。采用先前开发的随机森林模型来估算臭氧的居住暴露情况。我们应用分层 Cox 比例风险模型来估算臭氧与心血管疾病总死亡率、缺血性心脏病死亡率和中风死亡率之间的关系。这些模型按年龄和性别分层，并调整了一系列个体水平和地区水平的协变量。在之前的 1-3 年的暖季平均臭氧浓度作为时变变量加入。我们还按年龄、性别、教育程度、吸烟状况、城乡居住和地理区域进行了亚组分析。
对 96955 名参与者进行了数据分析。在随访期间，暖季平均臭氧浓度为 89.7μg/m（SD 14.4）。在完全调整的模型中，我们观察到臭氧与心血管疾病总死亡率（暖季臭氧浓度每增加 10μg/m，风险比[HR]为 1.093[95%CI 1.046-1.142]）、缺血性心脏病死亡率（暖季臭氧浓度每增加 10μg/m，HR 为 1.184[1.099-1.276]）和中风死亡率（暖季臭氧浓度每增加 10μg/m，HR 为 1.063[1.002-1.128]）之间存在显著且正向的关系。在调整细颗粒物后，与心血管疾病总死亡率和缺血性心脏病死亡率的关联几乎没有变化，而与中风死亡率的关联则失去了统计学意义。臭氧与心血管疾病死亡率之间的长期暴露关联在 65 岁及以上人群中比在 65 岁以下人群中更为显著。我们没有发现性别、教育程度、吸烟状况、城乡居住和地理区域有任何的效应修饰作用。我们观察到臭氧与心血管疾病死亡率之间几乎呈线性的暴露-反应关系。
这项研究是我们所知的第一项在中等收入环境下进行的全国性队列研究，表明长期臭氧暴露会增加心血管疾病死亡率的风险，特别是缺血性心脏病的死亡率。从这项研究中生成的暴露-反应关系曲线可能为未来的空气质量标准修订和环境健康影响评估提供信息。
国家自然科学基金。
