Background

Air pollution is a major environmental hazard to human health and a leading cause of morbidity for asthma worldwide.

Objectives

To assess the current evidence on short-term effects (from several hours to 7 days) of exposure to ozone (O₃), nitrogen dioxide (NO₂), and sulphur dioxide (SO₂) on asthma exacerbations, defined as emergency room visits (ERVs) and hospital admissions (HAs).

Methods

We searched PubMed/MEDLINE, EMBASE and other electronic databases to retrieve studies that investigated the risk of asthma-related ERVs and HAs associated with short-term exposure to O₃, NO₂, or SO₂. We evaluated the risks of bias (RoB) for individual studies and the certainty of evidence for each pollutant in the overall analysis. A subgroup analysis was performed, stratified by sex, age, and type of asthma exacerbation. We conducted sensitivity analysis by excluding the studies with high RoB and based on the E-value. Publication bias was examined with the Egger’s test and with funnel plots.

Results

Our literature search retrieved 9,059 articles, and finally 67 studies were included, from which 48 studies included the data on children, 21 on adults, 14 on the elderly, and 31 on the general population. Forty-three studies included data on asthma ERVs, and 25 on asthma HAs. The pooled relative risk (RR) per 10 µg/m³ increase of ambient concentrations was 1.008 (95%CI: 1.005, 1.011) for maximum 8-hour daily or average 24-hour O₃, 1.014 (95%CI: 1.008, 1.020) for average 24-hour NO₂, 1.010 (95%CI: 1.001, 1.020) for 24-hour SO₂, 1.017 (95%CI: 0.973, 1.063) for maximum 1-hour daily O₃, 0.999 (95%CI: 0.966, 1.033) for 1-hour NO₂, and 1.003 (95%CI: 0.992, 1.014) for 1-hour SO₂. Heterogeneity was observed in all pollutants except for 8-hour or 24-hour O₃ and 24-hour NO₂. In general, we found no significant differences between subgroups that can explain this heterogeneity. Sensitivity analysis based on the RoB showed certain differences in NO₂ and SO₂ when considering the outcome or confounding domains, but the analysis using the E-value showed that no unmeasured confounders were expected. There was no major evidence of publication bias. Based on the adaptation of the Grading of Recommendations Assessment, Development and Evaluation, the certainty of evidence was high for 8-hour or 24-hour O₃ and 24-hour NO₂, moderate for 24-hour SO₂, 1-hour O₃, and 1-hour SO₂, and low for 1-hour NO₂.

Conclusion

Short-term exposure to daily O₃, NO₂, and SO₂ was associated with an increased risk of asthma exacerbation in terms of asthma-associated ERVs and HAs.

中文翻译：

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短期接触臭氧，二氧化氮和二氧化硫以及哮喘导致的急诊就诊和住院：系统评价和荟萃分析

背景

空气污染是对人类健康的主要环境危害，也是全球哮喘发病的主要原因。

目标

评估有关暴露于臭氧（O ₃），二氧化氮（NO ₂）和二氧化硫（SO ₂）对哮喘恶化的短期影响（从数小时到7天）的最新证据，这被定义为急诊室就诊（ERV）和医院入院（HAs）。

方法

我们搜索了PubMed / MEDLINE，EMBASE和其他电子数据库，以检索研究与短期暴露于O ₃，NO ₂或SO ₂相关的哮喘相关ERV和HA的风险的研究。我们评估了个别研究的偏倚（RoB）风险，以及整体分析中每种污染物的证据确定性。进行了亚组分析，按性别，年龄和哮喘加重类型分层。我们通过排除具有较高RoB的研究并基于E值进行了敏感性分析。用Egger检验和漏斗图检查出版偏倚。

结果

我们的文献检索检索到9,059篇文章，最后纳入67篇研究，其中48篇研究包括儿童数据，21篇关于成年人的数据，14篇关于老年人的数据和31篇关于一般人群的数据。四十三项研究包括哮喘ERV的数据和25项关于哮喘HA的数据。对于每天最多8小时或平均24小时O ₃，每增加10 µg / m ³浓度，合并的相对风险（RR）为1.008（95％CI：1.005，1.011），1.014（95％CI：1.008，平均24小时NO ₂为1.020），24小时SO ₂为1.010（95％CI：1.001，1.020），每天最多1小时O ₃为1.017（95％CI：0.973，1.063），0.999（95％）一小时NO _2的CI：0.966，1.033）和一小时SO _2的1.003（95％CI：0.992，1.014）₂。除了8小时或24小时O ₃和24小时NO ₂以外，所有污染物均观察到异质性。通常，我们发现亚组之间没有显着差异可以解释这种异质性。当考虑结果或混淆域时，基于RoB的灵敏度分析显示NO ₂和SO ₂有一定差异，但是使用E值进行的分析表明，没有未测的混杂因素。没有发表偏见的主要证据。根据建议评估，发展和评估等级的调整，对于8小时或24小时O ₃和24小时NO ₂，证据的确定性很高。，适度为24小时SO _2，1小时O ₃和1小时SO ₂，低为1小时NO ₂。

结论

就哮喘相关的ERV和HA而言，每天短期暴露于O ₃，NO ₂和SO ₂会增加哮喘加重的风险。