Imaging Institute, Cleveland Clinic, L10, Cleveland, OH, USA.
Department of Quantitative Health Sciences, Cleveland Clinic, JJN3, Cleveland, OH, USA.
Ann Work Expo Health. 2021 May 3;65(4):463-474. doi: 10.1093/annweh/wxaa125.
N95 filtering facepiece respirators (N95 FFRs) and surgical masks are comprised of multiple layers of nonwoven polypropylene. Tight-fitting N95 FFRs are respiratory protective devices (RPDs) designed to efficiently filter aerosols. During the COVID-19 pandemic, health care workers (HCWs) throughout the world continue to face shortages of disposable N95 FFRs. Existing version of widely available FDA cleared loose-fitting surgical masks with straps do not provide reliable protection against aerosols. We tested the faceseal of a modified strapless form-fitting sealed version of surgical mask using quantitative fit testing (QNFT) and compared the performance of this mask with that of N95 FFRs and unmodified loose-fitting surgical masks.
Twenty HCWs participated in the study (10 women; 10 men; age 23-59 years). To create the sealed surgical masks, we removed the straps from loose-fitting surgical masks, made new folds, and used adhesive medical tape to secure the new design. All participants underwent QNFT with a loose-fitting surgical mask, the sealed surgical mask, and an N95 FFR; fit factors were recorded. Each QNFT was performed using a protocol of four exercises: (i) bending over, (ii) talking, (iii) moving head side to side, and (iv) moving head up and down. When the overall fit factor for the sealed surgical mask or N95 FFR was <100, the participant retook the test. Participants scored the breathability and comfort of the sealed surgical mask and N95 FFR on a visual analog scale (VAS) ranging from 0 (unfavorable) to 10 (favorable).
The median fit factor for the sealed surgical mask (53.8) was significantly higher than that of the loose-fitting surgical mask (3.0) but lower than that of the N95 FFR (177.0) (P < 0.001), equating to significantly lower inward leakage of ambient aerosols (measuring 0.04-0.06 µm) with the sealed surgical mask (geometric mean 1.79%; geometric standard deviation 1.45%; range 0.97-4.03%) than with the loose-fitting surgical mask (29.5%; 2.01%; 25-100.0%) but still higher than with the N95 FFR (0.66%; 1.46%; 0.50-1.97%) (P < 0.001). Sealed surgical masks led to a marked reduction (range 60-98%) in inward leakage of aerosols in all the participants, compared to loose-fitting surgical masks. Among the exercises, talking had a greater effect on reducing overall fit factor for the sealed surgical mask than for the N95 FFR; when talking was excluded, the fit factor for the sealed surgical mask improved significantly (median 53.8 to 81.5; P < 0.001). The sealed surgical mask, when compared with the N95 FFR, offered better reported breathability (median VAS 9 versus 5; P < 0.001) and comfort (9 versus 5; P < 0.001).
Widely available loose-fitting surgical masks can be easily modified to achieve faceseal with adhesives. Unlike loose-fitting surgical masks, sealed surgical masks can markedly reduce inward leakage of aerosols and may therefore offer useful levels of respiratory protection during an extreme shortage of N95 FFRs and could benefit HCWs who cannot comply with N95 FFRs due to intolerance. However, because a wide range of surgical masks is commercially available, individual evaluation of such masks is highly recommended before sealed versions are used as RPDs.
N95 过滤式面罩（N95 FFR）和手术口罩由多层无纺聚丙烯制成。贴合紧密的 N95 FFR 是设计用来高效过滤气溶胶的呼吸防护设备（RPD）。在 COVID-19 大流行期间，世界各地的医护人员（HCW）继续面临一次性 N95 FFR 短缺的问题。现有的广泛可用的带有带扣的宽松型经过 FDA 认证的手术口罩不能提供可靠的气溶胶防护。我们使用定量拟合测试（QNFT）对面罩的脸部密封进行了测试，并将其性能与 N95 FFR 和未修改的宽松型手术口罩进行了比较。
20 名 HCW 参加了这项研究（10 名女性；10 名男性；年龄 23-59 岁）。为了制作密封式手术口罩，我们从宽松型手术口罩上取下带子，进行了新的折叠，并使用医用胶带固定新设计。所有参与者都接受了宽松型手术口罩、密封式手术口罩和 N95 FFR 的 QNFT；记录拟合因子。每个 QNFT 都使用四个练习的协议进行：（i）弯腰，（ii）说话，（iii）左右转头，（iv）上下抬头。当密封式手术口罩或 N95 FFR 的整体拟合因子<100 时，参与者重新进行测试。参与者使用视觉模拟量表（VAS）对密封式手术口罩和 N95 FFR 的透气性和舒适度进行评分，范围从 0（不赞成）到 10（赞成）。
密封式手术口罩的中位拟合因子（53.8）明显高于宽松型手术口罩（3.0），但低于 N95 FFR（177.0）（P<0.001），这意味着与宽松型手术口罩（29.5%；2.01%；25-100.0%）相比，密封式手术口罩对内流气溶胶的泄漏明显更低（测量值为 0.04-0.06 µm），但仍高于 N95 FFR（0.66%；1.46%；0.50-1.97%）（P<0.001）。与宽松型手术口罩相比，密封式手术口罩使所有参与者的气溶胶内漏明显减少（范围为 60-98%）。在所有练习中，说话比 N95 FFR 更能降低密封式手术口罩的整体拟合因子；当排除说话时，密封式手术口罩的拟合因子显著改善（中位数 53.8 到 81.5；P<0.001）。与 N95 FFR 相比，密封式手术口罩提供了更好的透气性（中位数 VAS 9 比 5；P<0.001）和舒适度（中位数 9 比 5；P<0.001）。
广泛可用的宽松型手术口罩可以通过使用粘合剂轻松修改，以实现面部密封。与宽松型手术口罩不同，密封式手术口罩可以显著减少气溶胶的内漏，因此在 N95 FFR 极度短缺期间可能提供有用的呼吸保护水平，并可能使不能遵守 N95 FFR 的 HCW 受益。然而，由于有大量的手术口罩可供商业使用，在将密封式版本用作 RPD 之前，强烈建议对这些口罩进行单独评估。
