BACKGROUND Over 120 million people in the USA live in areas with unsafe ozone (O3) levels. Studies among adults have linked exposure to worse lung function and higher risk of asthma and chronic obstructive pulmonary disease (COPD). However, few studies have examined the effects of O3 in children, and existing studies are limited in terms of their geographic scope or outcomes considered. METHODS We leveraged a dataset of encounters at 42 US children's hospitals from 2004-2015. We used a one-stage case-crossover design to quantify the association between daily maximum 8-hour O3 in the county in which the hospital is located and risk of emergency department (ED) visits for any cause and for respiratory disorders, asthma, respiratory infections, allergies and ear disorders. RESULTS Approximately 28 million visits were available during this period. Per 10 ppb increase, warm-season (May through September) O3 levels over the past three days were associated with higher risk of ED visits for all causes (risk ratio [RR]: 0.3% [95% confidence interval (CI): 0.2%, 0.4%]), allergies (4.1% [2.5%, 5.7%]), ear disorders (0.8% [0.3%, 1.3%]) and asthma (1.3% [0.8%, 1.9%]). When restricting to levels below the current regulatory standard (70 ppb), O3 was still associated with risk of ED visits for all-cause, allergies, ear disorders and asthma. Stratified analyses suggest that the risk of O3-related all-cause ED visits may be higher in older children. CONCLUSIONS Results from this national study extend prior research on the impacts of daily O3 on children's health and reinforce the presence of important adverse health impacts even at levels below the current regulatory standard in the USA.

中文翻译：

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美国暖季环境臭氧与儿童健康。


背景技术 美国有超过 1.2 亿人生活在臭氧 (O3) 水平不安全的地区。针对成年人的研究表明，暴露于空气中会导致肺功能恶化以及哮喘和慢性阻塞性肺病 (COPD) 的风险增加。然而，很少有研究探讨 O3 对儿童的影响，并且现有研究在地理范围或考虑的结果方面受到限制。方法 我们利用 2004 年至 2015 年 42 家美国儿童医院的就诊数据集。我们使用一阶段病例交叉设计来量化医院所在县每日最大 8 小时 O3 与因任何原因以及呼吸系统疾病、哮喘、呼吸系统疾病而急诊科 (ED) 就诊的风险之间的关联。感染、过敏和耳部疾病。结果 在此期间，访问量约为 2800 万次。每增加 10 ppb，暖季（5 月至 9 月）过去三天的 O3 水平与各种原因就诊的急诊室就诊风险较高相关（风险比 [RR]：0.3% [95% 置信区间 (CI)：0.2） %, 0.4%]）、过敏（4.1% [2.5%, 5.7%]）、耳部疾病（0.8% [0.3%, 1.3%]）和哮喘（1.3% [0.8%, 1.9%]）。当限制在低于当前监管标准 (70 ppb) 的水平时，O3 仍然与因全因、过敏、耳部疾病和哮喘而去急诊室就诊的风险相关。分层分析表明，年龄较大的儿童因 O3 相关的全因急诊就诊的风险可能更高。结论 这项全国性研究的结果扩展了关于每日 O3 对儿童健康影响的先前研究，并强化了即使低于美国现行监管标准的水平也存在重要的不利健康影响。