医用N95防护口罩定性适合性检验与佩戴者主观评价问卷调查

目的 通过分析医用N95防护口罩的客观定性适合性检验结果与佩戴者对口罩主观评价结果的一致性,为医务人员科学选择防护口罩提供科学依据。方法 于2021年8月11日-29日对221名南京新冠定点医院工作人员进行调查,采用美国职业安全健康管理局(OSHA)认可的苦味剂气溶胶法(3MTMFT-30)设计的问卷进行现场收集调查,利用SPSS23.0软件对数据进行数据统计分析。结果 敏感性测试中,共201人(90.95%)通过测试,其中1级敏感度169人(76.47%)、2级敏感度30人(13.57%)、3级敏感度2人(0.90%);客观定性适合性检验方面,通过率为92.04%(185/201),其中第一次检验通过180人,第二次检验通过5人;佩戴者主观评价方面,111人主观整体感受较好,占55.22%,其中张嘴辅助呼吸、口罩气味、经面部肌肉调整后密合性三项得分分别为(2.10±0.58)分、(2.13±0.42)分、(2.46±0.56)分,均低于整体主观评价得分为(2.55±0.50)分,且主观评价口罩佩戴使用前密合性和经面部肌肉调整后密合性比较差异具有统计学意义(χ²=17.840,P<0.05);客观定性适合性检验结果与佩戴者主观评价的一致性差,kappa值为0.174(P<0.001)。结论 在客观定性适合性检验中,医用N95防护口罩安全性能较高,在适合性好的基础上增加口罩佩戴的舒适度,提高佩戴者的整体主观评价,充分利用测试结果为医务人员正确选择和有效使用的防护口罩。     

医务人员佩戴1860型微粒防护N95口罩的适合性及不适主观症状分析

目的检验N95防护口罩与中国医务人员面部的适合性及佩戴后的不适表现,为医务人员佩戴口罩提供科学依据。方法采用定性的方式检验3M公司提供的1860型微粒防护N95口罩中的杯罩式和折叠式VI罩对医务人员的适合程度。随访观察1个月,记录医务人员佩戴口罩出现的不适症状。结果共纳入研究对象1283人,其中198人仅参与了杯罩式口罩的适合性检测,826人仅参与了折叠式口罩的适合性检测,259人参与了上述两种口罩的适合性检测。杯罩式与折叠式口罩的适合性检测通过率分别为100％和98．9％。未通过折叠式口罩适合性检测的12名研究对象中有11名因脸形不合适,1名因感觉憋气不能完成检验。佩戴口罩的不适症状主要包括压迫面部（22．5％）、憋气（19．9％）和过敏（11．7％）。结论1860型微粒防护N95口罩适合大多数中国人脸形,普通医务人员在佩戴该型口罩前可以不进行适合性检验,但从事高危操作的医务人员必须进行适合性检验;长时间佩戴该型口罩可能引起较多的不适症状。     

外科口罩覆盖N95自吸过滤式防护口罩:增加泄漏风险

本报告通过对相关流体力学和密封压力的分析建模,论证了当N95自吸过滤式防护口罩(N95 FFR)被外科口罩、布口罩或医用口罩(统称为外科口罩)覆盖时,将增加颜面部与口罩之间密封泄漏的潜在风险。以前发表的关于呼吸器压力和泄漏的试验研究也适用于此问题。在可预见的未来,正确使用N95 FFR仍将是保证医护人员安全的重要组成部分,特别是对于那些从事产生气溶胶操作(AGP)(如气管插管)的人员。在考虑泄漏风险时,重要的是要了解哪些因素可能会影响颜面部与口罩之间的密封性。N95 FFR的适配度和密封性会随着反复的穿戴和落纱而退化。据报道,一些N95 FFR再处理或回收技术可以加速这种退化。简而言之,N95型口罩密封性容易受损,可能会受到多种因素的影响。     

外科口罩与N95口罩预防流感效果荟萃分析

目的 评价外科口罩与N95口罩预防流感效果.方法 检索Cochrane Library临床对照试验资料库、PubMed、EMbase、中国生物医学文献数据库和中国期刊全文数据库;纳入外科口罩与N95口罩预防流感的随机对照试验,进行荟萃分析及系统评价.结果 筛选符合纳入标准的随机对照试验3项,共2049名研究者;荟萃分析发现,外科口罩组与N95口罩组流感发生率的差异无统计学意义;外科口罩组与N95口罩组其他呼吸道病毒(SARS病毒除外)检出率的差异无统计学意义.结论 外科口罩与N95口罩对流感病毒的防护效果无差异.     

自吸过滤式防尘口罩的适合性与防护效果研究进展

自吸过滤式防尘口罩是最常用的个人呼吸防护用品,其防护效果取决于口罩滤料的过滤效率和与佩戴者的适合程度,即适合性。目前口罩设计多使用美国上世纪70年代的分栏,研究显示这些口罩对国人脸型的适合性较差。为提高防尘口罩的适合性,通过5 008名成年汉族人头面尺寸的工效学测量,建立了以脸长和脸宽为基础的口罩适合性检验颜面分栏,可用于口罩的设计和检测,提高其适合性。同时,建议在佩戴防尘口罩之前,除专业佩戴培训外,进行防护效果的适合性测定,以保证口罩的防护效果。     

N95防护口罩对结核病防治机构从业人员患病状况的影响

采用调查问卷方式,对辽宁省内结核病防治机构从业人员患病情况及N95防护口罩使用情况进行调查,分析感染控制的影响因素,建立预防控制措施。     

自吸过滤式防尘口罩的适合性测试及改进

目的 研究自吸过滤式防尘口罩对中国成年人的适用性,分析影响适合性的主要因素;结合中国人头面特征进行改进,并评价改进后的防护效果.方法 依据前期研究提出的中国人群头面尺寸二元分栏选择代表性测试对象,对市场上购买的杯状(A1)和折叠型(B1)自吸过滤式防尘口罩使用核凝计数器法进行适合性测试.依据中国人头面特征以及适合性影响因素对A1和B1两类自吸过滤式防尘口罩进行改进,并对上述口罩改进后的对应产品A2和B2测定适合性.结果 按适合性因数大于等于100为自吸过滤式防尘口罩的防护效果合格标准,A1型自吸过滤式防尘口罩的通过率为0.0％,适合性因数为20.7(范围:6.9~46.9);B1型自吸过滤式防尘口罩的通过率为4.0％,适合因数为26,0(范围:6.8～154.9).改进后两类自吸过滤式防尘口罩的通过率和适合性因数均提高,A2型自吸过滤式防尘口罩的通过率为72.0％,适合性因数为223.5(范围:2.2～5932.7),与改进前比较,差异有统计学意义(x2=25.09,P＜0.05).B2型的通过率为88.0％,适合性因数为429.8(范围:41.5～3692.9),与改进前比较,差异有统计学意义(x2=32.21,P＜0.05).结论 为保证自吸过滤式防尘口罩的防护效果,其设计需考虑国人脸型特点,劳动者选择自吸过滤式防尘口罩时应进行适合性测定.     

常用N95型自吸过滤式防尘口罩阻力与过滤效率及影响因素

目的 研究N95型自吸过滤式防尘口罩过滤效率和吸气阻力的影响因素,为降低阻力和提高口罩过滤效率提供改进依据.方法 购买目前市场销量领先且已获得认证的6个品牌,共21个型号的N95防尘口罩,在10～100L/min流量下测量口罩的过滤效率及吸气阻力,以过滤效率大于95％,吸气阻力小于350 Pa为合格标准,分析不同因素对口罩性能的影响.结果 全部21个型号的口罩中有2个型号的过滤效率低于95％,合格率为90.47％,过滤效率随流量增大而下降,呈线性负相关(r2=0.711,P＜0.05).所有口罩的吸气阻力均符合国家标准的要求.吸气阻力随流量提高而增大,二者呈线性正相关(r2=0.878,P＜0.05).不同品牌口罩的吸气阻力、过滤效率的差异有统计学意义(P＜0.05);同一品牌不同型号口罩的过滤效率的差异无统计学意义(P＞0.05),但吸气阻力的差异有统计学意义(P＜0.05);未见通气阀对阻力和过滤效率的影响.结论 本研究测试的N95型防尘口罩吸气阻力均达到国家标准要求,过滤效率达标率超过90％.影响口罩吸气阻力的因素有口罩材质、尺寸和通气流量,影响口罩过滤效率的因素是口罩材质和通气流量.     

医用口罩防护性能的监测与评价

目的了解医用口罩的防护效果。方法参照国家相关标准,利用人工发生的标准气溶胶对口罩材料、佩戴泄漏量等参数进行了监测与分析。结果国产医用无纺布口罩对于0.3μm直径的气溶胶,防护效率仅达20.0%～25.0%。结论医用口罩标准、医务人员个人防护意识有待提高,医疗环境有待改善。     

医务人员对不同品牌医用防护口罩的主观感受与适合性测试结果

 目的 了解医务人员对不同品牌医用防护口罩密合性感受和舒适度感受的差异。方法 选取发热门诊的工作人员,包括医生、护士、医技、工勤人员,对四个品牌的折叠形医用防护口罩进行定量适合性测试,调查不同动作时医务人员主观感受密合性情况,并调查测试时和佩戴4h后医务人员鼻梁区压迫感、皮肤痒、颜面部皮肤损伤、内表面磨嘴、勒耳廓、面部压迫感等不适感受,以及佩戴4h后口罩变形等特殊情况。结果 共对发热门诊98名工作人员进行了医用防护口罩佩戴适合性测试和舒适度调查,与定量适合性测试结果相比,主观感受真正密合的符合率为77.42%;主观感受真正非密合的符合率为56.86%。不同测试动作中,除大声说话动作之外,其他动作主观感受真正密合性符合率均在90%以上,而真正非密合符合率各项动作均较低,均在30%以下。口罩佩戴主观感受反映的主要问题为大小不合适、头带拉力不舒适、鼻梁区压迫感,整体不适感受人员比率在40%左右。佩戴4h后,头带拉力不舒适、鼻梁区压迫感人员比例所有增加。结论 选择医用防护口罩时,除考虑适合性测试数据外,还需综合考虑舒适度等主观感受,可提高医用防护口罩佩戴的依从性和正确性,并提高医务人员满意度。     

错误的安全感更危险——个人呼吸防护九大误区

目的评价公共卫生应急人员对常用N95防护口罩的适合性,比较适合性测试结果与佩戴气密性主观评价结果的一致性,指导公共卫生应急人员科学选用防护口罩。方法采用环境气溶胶冷凝核计数器法,对235名上海市市、区两级疾病预防控制中心公共卫生应急人员进行定量适合性测试;通过问卷法调查佩戴气密性主观评价,比较适合性测试结果与佩戴气密性主观评价结果的一致性。结果160人通过适合性测试,通过率为68.1%;通过各项测试动作佩戴气密性主观评价结果与适合性测试通过率的一致性比较,kappa值范围为-0.09~0.43,除测试动作5(大声说话)的kappa值＞0.4,其他6个测试动作的kappa值均＜0.4,测试动作8(正常呼吸)的kappa值和符合率均为最低,分别为0.09和49.7%。结论口罩佩戴气密性主观评价结果的准确性较差,无法反映真实防护效果,无法取代适合性测试。建议公共卫生应急人员以适合性测试结果为依据,正确选择和使用适合的呼吸防护产品,以保证高水平的呼吸防护效果。     

Manikin-based performance evaluation of N95 filtering-facepiece respirators challenged with nanoparticles

Protection of the human respiratory system from exposure to nanoparticles is becoming an emerging issue in occupational hygiene. The potential adverse health effects associated with particles of approximately 1-100 nm are probably greater than submicron or micron-sized particles. The performance of two models of N95 half-facepiece-filtering respirators against nano-sized particles was evaluated at two inhalation flow rates, 30 and 85 l min(-1), following a manikin-based protocol. The aerosol concentration was measured outside and inside the facepiece using the Wide-Range Particle Spectrometer. Sodium chloride particles, conventionally used to certify N-series respirators under NIOSH 42 CFR 84 regulations, were utilized as the challenge aerosol. The targeted particle sizes ranged from 10 to 600 nm, although the standard certification tests are performed with particles of approximately 300 nm, which is assumed to be the most penetrating size. The results indicate that the nanoparticle penetration through a face-sealed N95 respirator may be in excess of the 5% threshold, particularly at high respiratory flow rates. Thus, N95 respirators may not always provide the expected respiratory protection for workers. The highest penetration values representing the poorest respirator protection conditions were observed in the particle diameter range of approximately 30-70 nm. Based on the theoretical simulation, we have concluded that for respirators utilizing mechanical filters, the peak penetration indeed occurs at the particle diameter of approximately 300 nm; however, for pre-charged fiber filters, which are commonly used for N95 respirators, the peak shifts toward nano-sizes. This study has confirmed that the neutralization of particles is a crucial element in evaluating the efficiency of a respirator. The variability of the respirator's performance was determined for both models and both flow rates. The analysis revealed that the coefficient of variation of the penetration ranged from 0.10 to 0.54 for particles of 20-100 nm in diameter. The fraction of N95 respirators for which the performance test at 85 l min(-1) demonstrated excessive (>5%) penetration of nanoparticles was as high as 9/10. The test results obtained in a relatively small (0.096 m(3)) test chamber and in a large (24.3 m(3)) walk-in chamber were found essentially the same, thus, suggesting that laboratory-based evaluations have a good potential to adequately represent the respirator field performance.     

Recommended test methods and pass/fail criteria for a respirator fit capability test of half-mask air-purifying respirators

This study assessed key test parameters and pass/fail criteria options for developing a respirator fit capability (RFC) test for half-mask air-purifying particulate respirators. Using a 25-subject test panel, benchmark RFC data were collected for 101 National Institute for Occupational Safety and Health-certified respirator models. These models were further grouped into 61 one-, two-, or three-size families. Fit testing was done using a PortaCount® Plus with N95-Companion accessory and an Occupational Safety and Health Administration-accepted quantitative fit test protocol. Three repeated tests (donnings) per subject/respirator model combination were performed. The panel passing rate (PPR) (number or percentage of the 25-subject panel achieving acceptable fit) was determined for each model using five different alternative criteria for determining acceptable fit.

When the 101 models are evaluated individually (i.e., not grouped by families), the percentages of models capable of fitting >75% (19/25 subjects) of the panel were 29% and 32% for subjects achieving a fit factor ≥100 for at least one of the first two donnings and at least one of three donnings, respectively. When the models are evaluated grouped into families and using >75% of panel subjects achieving a fit factor ≥100 for at least one of two donnings as the PPR pass/fail criterion, 48% of all models can pass. When >50% (13/25 subjects) of panel subjects was the PPR criterion, the percentage of passing models increased to 70%.

Testing respirators grouped into families and evaluating the first two donnings for each of two respirator sizes provided the best balance between meeting end user expectations and creating a performance bar for manufacturers. Specifying the test criterion for a subject obtaining acceptable fit as achieving a fit factor ≥100 on at least one out of the two donnings is reasonable because a majority of existing respirator families can achieve an PPR of >50% using this criterion. The different test criteria can be considered by standards development organizations when developing standards.     

Temporal changes in filtering-facepiece respirator fit

A three-year study examined changes in N95 filtering-facepiece respirator (FFR) fit at six-month intervals and the relationship between fit and changes in weight for 229 subjects. During each visit, subjects performed a total of nine fit tests using three samples of the same FFR model. Inward leakage and filter penetration were measured for each donned respirator to determine face seal leakage (FSL). A total of 195 subjects completed the second visit and 134 subjects completed all seven visits. Acceptable fit was defined as 90th percentile FSL ≤ 5% and at least one fit factor ≥ 100. An unacceptable fit was observed for 14, 10, 7, 12, 15, and 16% of subjects on Visits 2–7, respectively. The predicted risk of an unacceptable fit increased with increasing length of time between fit tests, from 10% at Year 1 to 20% at Year 2 and to 25% at Year 3. Twenty-four percent of subjects who lost ≥ 20 lb had an unacceptable fit; these percentages ranged from 7–17% for subjects with lower weight losses or any degree of weight gain. Results support the current OSHA requirement for annual fit testing and suggest that respirator users who lose more than 20 lb should be re-tested for respirator fit.     

In vivo protective performance of N95 respirator and surgical facemask

BACKGROUND: The SARS outbreak in 2003 has spawned a major controversy concerning protective performance facemasks for healthcare workers. This study reports a study on in-vivo protective performance of surgical masks and N95 respirators. METHODS: Typical surgical masks and N95 respirators used in Hong Kong hospitals were tested in comparison with those treated with nano-functional materials (called nano-masks) on various physical properties and in-vivo wear filtration efficiency, as well as usability test in hospitals for surgical masks. RESULTS: Tests on physical properties showed that N95 respirators had significantly lower air permeability and water vapor permeability than surgical masks. The in-vivo filtration tests illustrated that N95 respirators filtered out 97% of potassium chloride (KCl) solution, while surgical masks filtered out 95% of KCl solution. Nano-masks show stronger water repellency and antibacterial activities, but no difference in usability, comparing with normal N95 and surgical masks. CONCLUSIONS: Surgical masks can provide in-vivo filtration protection of 95% filtration efficiency. N95 respirators provide higher in-vivo filtration efficiency of 97% with significant reduction of air permeability and water vapor permeability. Compared to normal surgical masks/respirators, the nano-masks can provide additional protective functions in stopping capillary diffusion and antibacterial activities.     

Comparison of qualitative and quantitative fit-testing results for three commonly used respirators in the healthcare sector

N95 filtering facepiece respirators are used by healthcare workers when there is a risk of exposure to airborne hazards during aerosol-generating procedures. Respirator fit-testing is required prior to use to ensure that the selected respirator provides an adequate face seal. Two common fit-test methods can be employed: qualitative fit-test (QLFT) or quantitative fit-test (QNFT). Respiratory protection standards deem both fit-tests to be acceptable. However, previous studies have indicated that fit-test results may differ between QLFT and QNFT and that the outcomes may also be influenced by the type of respirator model. The aim of this study was to determine if there is a difference in fit-test outcomes with our suite of respirators, 3M - 1860S, 1860, AND 1870, and whether the model impacts the fit-test results.

Subjects were recruited from residential care facilities. Each participant was assigned a respirator and underwent sequential QLFT and QNFT fit-tests and the results (either pass or fail) were recorded. To ascertain the degree of agreement between the two fit-tests, a Kappa (Κ) statistic was conducted as per the American National Standards Institute (ANSI) respiratory protection standard. The pass-fail rates were stratified by respirator model and a Kappa statistic was calculated for each to determine effect of model on fit-test outcomes.

We had 619 participants and the aggregate Κ statistic for all respirators was 0.63 which is below the suggested ANSI threshold of 0.70. There was no statistically significant difference in results when stratified by respirator model.

QNFT and QLFT produced different fit-test outcomes for the three respirator models examined. The disagreement in outcomes between the two fit-test methods with our suite of N95 filtering facepiece respirators was approximately 12%. Our findings may benefit other healthcare organizations that use these three respirators.     

Assessing real-time performances of N95 respirators for health care workers by simulated workplace protection factors

To assess performances of N95 respirators for Health Care Workers (HCWs) in a simulatedhealth-care setting, we measured the Simulated Workplace Protection Factors (SWPFs) inreal-time from the volunteers. A total of 49 study subjects, wearing 3 M respirator ModelN95 1860 and 1860S, were fit tested using the OSHA Exercise Regimen. The test subjectswere asked to perform simulated scenarios, including patient assessments, suction, andintravenous injection (IV) treatment. Two TSI PortaCount instruments continuously measuredconcentrations in the respirator and the room concentration. For Quantitative Fit Testing(QNFT), 36 out of 49 (73.5%) passed the fit factor (FF) criteria set at 100 and 13 (26.5%)failed. The results of QNFT were found to have a low correlation with SWPF, withR²=0.32. The geometric means (GM) and geometric standard deviations (GSD) ofSWPF were 68.8 (1.1) for those subjects who passed and 39.6 (1.3) for those who failed.Real-time assessments of SWPF showed that lower SWPFs were; moving head up and down, andbending at the waist. This study identifies the needs for providing different sizes ofrespirators for HCWs and the importance of performing fit tests for HCWs regularly. Andparticular movements were identified as attributing factors affecting more on SWPFs.