Background

Smoke-free policies in outdoor areas and semi-private and private places (eg, cars) might reduce the health harms caused by tobacco smoke exposure (TSE). We aimed to investigate the effect of smoke-free policies covering outdoor areas or semi-private and private places on TSE and respiratory health in children, to inform policy.

Methods

In this systematic review and meta-analysis, we searched 13 electronic databases from date of inception to Jan 29, 2021, for published studies that assessed the effects of smoke-free policies in outdoor areas or semi-private or private places on TSE, respiratory health outcomes, or both, in children. Non-randomised and randomised trials, interrupted time series, and controlled before–after studies, without restrictions to the observational period, publication date, or language, were eligible for the main analysis. Two reviewers independently extracted data, including adjusted test statistics from each study using a prespecified form, and assessed risk of bias for effect estimates from each study using the Risk of Bias in Non-Randomised Studies of Interventions tool. Primary outcomes were TSE in places covered by the policy, unplanned hospital attendance for wheezing or asthma, and unplanned hospital attendance for respiratory tract infections, in children younger than 17 years. Random-effects meta-analyses were done when at least two studies evaluated policies that regulated smoking in similar places and reported on the same outcome. This study is registered with PROSPERO, CRD42020190563.

Findings

We identified 5745 records and assessed 204 full-text articles for eligibility, of which 11 studies met the inclusion criteria and were included in the qualitative synthesis. Of these studies, seven fit prespecified robustness criteria as recommended by the Cochrane Effective Practice and Organization of Care group, assessing smoke-free cars (n=5), schools (n=1), and a comprehensive policy covering multiple areas (n=1). Risk of bias was low in three studies, moderate in three, and critical in one. In the meta-analysis of ten effect estimates from four studies, smoke-free car policies were associated with an immediate TSE reduction in cars (risk ratio 0·69, 95% CI 0·55–0·87; 161 466 participants); heterogeneity was substantial (I² 80·7%; p<0·0001). One additional study reported a gradual TSE decrease in cars annually. Individual studies found TSE reductions on school grounds, following a smoke-free school policy, and in hospital attendances for respiratory tract infection, following a comprehensive smoke-free policy.

Interpretation

Smoke-free car policies are associated with reductions in reported child TSE in cars, which could translate into respiratory health benefits. Few additional studies assessed the effect of policies regulating smoking in outdoor areas and semi-private and private places on children's TSE or health outcomes. On the basis of these findings, governments should consider including private cars in comprehensive smoke-free policies to protect child health.

Funding

Dutch Heart Foundation, Lung Foundation Netherlands, Dutch Cancer Society, Dutch Diabetes Research Foundation, Netherlands Thrombosis Foundation, and Health Data Research UK.

中文翻译：

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户外区域和私人场所无烟政策对儿童烟草烟雾暴露和呼吸系统健康的影响：系统评价和荟萃分析

背景

户外区域和半私人和私人场所（例如汽车）的无烟政策可能会减少烟草烟雾暴露 (TSE) 造成的健康危害。我们旨在调查覆盖户外区域或半私人和私人场所的无烟政策对儿童 TSE 和呼吸系统健康的影响，为政策提供信息。

方法

在这项系统评价和荟萃分析中，我们搜索了从成立之日到 2021 年 1 月 29 日的 13 个电子数据库，以查找评估户外区域或半私人或私人场所的无烟政策对 TSE、呼吸道疾病的影响的已发表研究。儿童的健康结果，或两者兼而有之。非随机和随机试验、中断时间序列和前后对照研究，不受观察期、发表日期或语言的限制，有资格进行主要分析。两名审查员独立提取数据，包括使用预先指定的表格从每项研究中调整的测试统计数据，并使用非随机干预研究中的偏倚风险工具评估每项研究的效果估计的偏倚风险。主要结果是政策涵盖的地方的 TSE，17 岁以下儿童因喘息或哮喘而意外入院，以及因呼吸道感染意外入院。随机效应荟萃分析是在至少有两项研究评估在相似地方规范吸烟并报告相同结果的政策时进行的。本研究已在 PROSPERO 注册，CRD42020190563。

发现

我们确定了 5745 条记录并评估了 204 篇全文文章的资格，其中 11 项研究符合纳入标准并被纳入定性综合。在这些研究中，七项符合 Cochrane 有效实践和护理组织建议的预先指定的稳健性标准，评估无烟汽车 (n=5)、学校 (n=1) 和涵盖多个领域的综合政策 (n= 1）。三项研究的偏倚风险较低，三项为中等，一项为严重。在对四项研究的十项效应估计值的荟萃分析中，无烟汽车政策与汽车中 TSE 的立即减少有关（风险比 0·69，95% CI 0·55–0·87；161 466 名参与者）；异质性很大（I ²80·7%；p<0·0001)。另一项研究报告称，汽车中的 TSE 每年都在逐渐减少。个别研究发现，在实行无烟学校政策后，学校场地的 TSE 减少，以及实行全面无烟政策后呼吸道感染的住院人数减少。

解释

无烟汽车政策与汽车中报告的儿童 TSE 减少有关，这可能转化为呼吸系统健康益处。很少有其他研究评估了在户外区域和半私人和私人场所规范吸烟的政策对儿童 TSE 或健康结果的影响。根据这些调查结果，政府应考虑将私家车纳入全面的无烟政策以保护儿童健康。

资金

荷兰心脏基金会、荷兰肺基金会、荷兰癌症协会、荷兰糖尿病研究基金会、荷兰血栓形成基金会和英国健康数据研究基金会。