BIC-EAST and SKL-ESPC, College of Environmental Sciences and Engineering and Centre for Environment and Health, Peking University, 5 Yiheyuan Road, Beijing, 100871, China.
School of Public Health, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China.
Part Fibre Toxicol. 2018 Jul 4;15(1):30. doi: 10.1186/s12989-018-0266-0.
Facemasks are increasingly worn during air pollution episodes in China, but their protective effects are poorly understood. We aimed to evaluate the filtration efficiencies of N95 facemasks and the cardiopulmonary benefits associated with wearing facemasks during episodes of pollution.
We measured the filtration efficiencies of particles in ambient air of six types of N95 facemasks with a manikin headform. The most effective one was used in a double-blind, randomized, controlled crossover study, involving 15 healthy young adults, conducted during 2 days of severe pollution in Beijing, China. Subjects were asked to walk along a busy-traffic road for 2 h wearing authentic or sham N95 facemasks. Clinical tests were performed four times to determine changes in the levels of biomarkers of airway inflammation, endothelial dysfunction, and oxidative stress within 24 h after exposure. The facemasks removed 48-75% of number concentrations of ambient air particles between 5.6 and 560 nm in diameter. After adjustments for multiple comparison, the exhaled nitric oxide level and the levels of interleukin-1α, interleukin-1β, and interleukin-6 in exhaled breath condensate increased significantly in all subjects; however, the increases in those wearing authentic facemasks were statistically significantly lower than in the sham group. No significant between-group difference was evident in the urinary creatinine-corrected malondialdehyde level. In arterial stiffness indicators, the ejection duration of subjects wearing authentic facemasks was higher after exposure compared to the sham group; no significant between-group difference was found in augmentation pressure or the augmentation index.
In young healthy adults, N95 facemasks partially reduced acute particle-associated airway inflammation, but neither systemic oxidative stress nor endothelial dysfunction improved significantly. The clinical significance of these findings long-term remains to be determined.
The trial registration number (TRN) for this study is ChiCTR1800016099 , which was retrospectively registered on May 11, 2018.
在中国空气污染事件期间，人们越来越多地佩戴口罩，但口罩的保护作用仍知之甚少。本研究旨在评估 N95 口罩的过滤效率，以及在污染期间佩戴口罩对心肺的益处。
我们使用头模测量了 6 种 N95 口罩对环境空气中颗粒物的过滤效率。其中过滤效果最好的一种口罩在一项双盲、随机、对照交叉研究中进行了测试，该研究纳入了 15 名健康的年轻成年人，在北京市严重污染期间的两天内进行。要求受试者佩戴真实或假的 N95 口罩，在交通繁忙的道路上行走 2 小时。在暴露后 24 小时内，进行 4 次临床检测，以确定气道炎症、内皮功能障碍和氧化应激生物标志物水平的变化。口罩去除了直径为 5.6-560nm 的环境空气中颗粒物数浓度的 48%-75%。经多重比较调整后，所有受试者的呼出气一氧化氮水平以及呼出气冷凝液中白细胞介素-1α、白细胞介素-1β 和白细胞介素-6 的水平均显著升高；然而，佩戴真实口罩的受试者的升高幅度明显低于假口罩组。尿液肌酐校正的丙二醛水平在两组间无显著差异。在动脉僵硬度指标中，佩戴真实口罩的受试者的射血时间在暴露后高于假口罩组；两组间的增强压或增强指数无显著差异。
在年轻健康成年人中，N95 口罩部分减轻了急性颗粒物相关的气道炎症，但系统性氧化应激或内皮功能障碍并无明显改善。这些发现的长期临床意义仍有待确定。
本研究的临床试验注册号为 ChiCTR1800016099，于 2018 年 5 月 11 日进行了回顾性注册。
