Understanding the regulations and critical characteristics of personal protective equipment (PPE)
By Dr. Davis Lee; Dr. Erin Kirkpatrick; Dr. A. Sydney Gladman; Dr. Emily Fitzharris; Michael Posson, M.P.H., CIH; and Dr. Mark Roberts1
textiles have long been used in protective coverings2，包括礼服，工作岗位，帽子和面部覆盖物。近几个月来，医疗保健行业，更广泛的劳动力和公众对使用保护性掩护来降低新型冠状病毒感染风险（SARS-COV-2）引起了很多兴趣和活动。因此，对这些产品的需求急剧增加。
In addition to regular use of personal protective equipment (PPE) in healthcare and occupational settings, this increased demand results from the Atlanta-based Centers for Disease Control’s (CDC’s) recommendation that the public wear “simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others.”3这些面部覆盖物被宽松地定义为“由家用物品制成的简单布脸部覆盖物或以低成本在家中制成的。”3通过建议为公众使用简单的动手（DIY）面部覆盖物，Covid-19-19是否为纺织工业创造了一个独特的机会来应对公众需求吗？
this article explores the regulations associated with PPE, surgical masks and unregulated protective face coverings. The specific regulatory definition of PPE, the performance standards and regulations that need to be met, and the pragmatic considerations related to fabric construction and end-use performance will be discussed. The information collected for this article is based on scientific and open sourced literature available at the time of this writing.
are made using nonwoven materials. Image: Mika Braumeister/
Unsplash.
Understanding The Regulatory Complexities Of PPE: Who Makes The Rules?
PPE has become a household term, but regulatory complexities and associated performance requirements are not commonly understood. In fact, PPE is a specific term regarding workplace protective equipment that is regulated and enforced by the Occupational Safety and Health Administration (OSHA) and other agencies. OSHA defines PPE as “equipment worn to minimize exposure to hazards that cause serious workplace injuries and illnesses.”4Especially within the context of disease transmission, it is important to note that PPE is designed to protect the wearer, not necessarily others who may come into close proximity to the wearer.
关于保护性掩护的大部分讨论涉及当前的Covid-19大流行侧重于保护性面部覆盖物。与OSHA一起，美国食品和药物管理局（FDA）和国家职业安全与健康研究所（NIOSH）也参与了保护掩护的指南。在协作的同时，这些机构的各自角色不同。FDA权限的范围包括对医疗设备的监管监督。5另一方面，尼什（Niosh）是一家研究机构，该研究机构“专注于研究工人安全和健康的研究，并赋予雇主和工人创建安全健康的工作场所”。6NIOSH也受OSHA的管辖权，是美国工作场所呼吸保护的认证机构。
respirator masks
Image: CDC/Pexels
What Are The Regulations?
PPE has very specific regulatory meaning. With regards to protective face coverings, there is a clear regulatory difference between PPE used in an occupational or healthcare setting — for example N95 respirators or surgical masks — and face coverings that may be used by the general public such as DIY face coverings as described by the CDC.3For example:
- Properly fitted N95 respirators for industrial use are capable of filtering out at least 95 percent of 0.3 micron size particles.7,8,9,10In the United States, PPE such as N95 respirators carry labels that designate the approval level — N95 — and approval by NIOSH under 42 CFR Part 84. NIOSH and the approved use — N95, for example — will be printed directly on the mask, and the packaging will be accompanied by information regarding OSHA compliance requirements and workplace hazards. In this case the employer is responsible for assuring that PPE is prescribed in accordance with the appropriate specifications, laws and regulations.
- Surgical masks for medical use are cleared by the FDA as a medical device but may or may not have NIOSH labeling or certification, depending on the product class and code.8,9,11Surgical masks differ from respirators in their indications for use. Specifically, the respirators are intended to filter small particles and bio-aerosols, whereas surgical masks are typically designed to fit the face more loosely and serve to act as a barrier to the transfer of large droplets of saliva and/or mucus.12,13
- 疾病预防控制中心定义的一般公共用途的面部覆盖物目前没有法规要求，也不需要遵守任何政府规格或法规。14Likewise, protective face coverings colloquially referred to as “surgical masks” that are for general public use and intended for a non-medical purpose are not required to meet governmental specifications or regulations. Protective face coverings used in this context are not technically considered PPE.8,9,15
Regardless of the type of protective covering chosen, it should always be used in conjunction with appropriate and basic hygiene practices, such as properly donning and doffing coverings or PPE, and then washing one’s hands.16,17
表现标准是什么？
If a respirator is to be used in a workplace as a PPE device under OSHA rule, it must go through a NIOSH certification process dictated in 42 CFR 84.18there are also other performance requirements or industry standards associated with different types of PPE, for example ANSI/ISEA Z87.1,19ANSI/ASSE Z88.2，20and ASTM F2100.21所有这些都是与成品相关的标准。另一方面，不需要根据任何有关过滤或个人保护的政府绩效标准对DIY面部覆盖（例如CDC推荐的面部覆盖物）进行测试。22因此,纺织indu有机会stry to characterize typical functional properties and potentially develop minimum performance specifications based on current regulatory requirements of face coverings.
In addition to the product characteristics, a critical factor to consider with respirators and face covering performance is the fit to the user’s face. Airflow will follow the path of least resistance. If the covering does not tightly contour the face, air will leak through gaps between the face and seal, reducing filtration effectiveness. In this respect, there is a critical distinction between respirators — which are regulated under OSHA — and face coverings, which are recommended by the CDC for the general public. For example, N95 respirators used in medical or occupational settings are required to be fit-tested to ensure the individual fit and filtration efficiency for the user. Further, the user is required, as facilitated by the employer to undergo medical examination, training, and other requirements to assure that they are able to wear a respirator during the course of their employment. In contrast, since general protective face coverings may fit the user’s face more loosely, filtration performance of the textile material may be reduced.22
在保护覆盖物中使用纺织品
It is generally understood that different protective coverings provide different levels of protection for the wearer and those around them. In these protective coverings, textile products are popular material choices because they simultaneously provide comfort and protection. For example, face masks and surgical masks used as PPE are typically constructed from nonwoven fabrics using fibers such as polypropylene, polyester and rayon.23However, conventional knit or woven fabrics also are used for certain protective coverings. A variety of fiber and fabric options are available for DIY face coverings.
文献回顾表明,许多研究hers have evaluated the utility and function of N95 respirators, surgical masks, and DIY face coverings. One study that evaluated the filtering efficiency of DIY face coverings and surgical masks for particles less than 10 microns found that the filtering efficiency of DIY face coverings ranged from approximately 60 to 80 percent, depending on the fabric characteristics, as compared to greater than 90 percent efficiency for the surgical masks, indicating that face coverings provide some level of protection for the general population.24研究发现，面部覆盖“将发射的颗粒（泄漏）减少了1/5，手术掩模将其降低1/2，而N95-等效掩膜的大小为0.02-1.0微米，将其降低了2/3英寸。25
Another study that examined DIY face coverings produced from readily available fabric types provides useful guidance regarding construction characteristics. Davies, Anna, et al, evaluated the filtration efficiency of a variety of household materials, including a cotton T-shirt, scarf, tea towel, and vacuum cleaner bags, against two microorganisms chosen to be representative of the influenza virus and published the results in the paper “Testing the efficacy of homemade masks: would they protect in an influenza pandemic?”26
the study showed the pillowcase and 100-percent cotton T-shirt to be the most suitable household materials for constructing DIY masks. Moreover, the doubling of fabric layers did not significantly increase the filtration efficiency but did negatively affect breathability. The filtration of these DIY face coverings was also compared to surgical masks. While the DIY face coverings were better than controls — no face covering — the improved filtration efficiency from surgical masks was three times that of DIY masks for blocking the transmission of microorganisms via coughing.
Understanding Fabric Characteristics For Protective Face Coverings
Existing literature provides guidance on how fabric characteristics impact protective face covering performance. For example, researchers have shown that DIY cloth face coverings can have varied pore sizes, shapes, and distributions.24这些研究支持一般的理解，即具有较大孔径的织物可提供较低水平的过滤效率。24
In addition to pore size, the number of available pores can be affected by a number of fabric, yarn and fiber characteristics. In general, fabric modifications that increase the number of pores, while making them smaller should improve filtration performance. For instance, simply by increasing the thread count of a fabric, the spaces between yarns — fabric interstices — will be increased in number while made smaller in size. This should improve filtration efficiency. However, breathability may be negatively impacted as seen in the study above,26有效提高织物缝在哪里is achieved by doubling the fabric layers.
Fiber type, size and shape will also affect the number and size of available pores. Smaller fibers and irregularly shaped fibers — cotton or trilobal man-made fibers, for example — will provide added surface area. With any of these modifications, breathability and comfort must also be considered.
织物特征可能会受到重新磨损，洗涤和消毒的影响
Filtering efficiency of face coverings may be adversely affected by re-wearing and laundering, as well as by repeated fit adjustment. Researchers have found that washing, drying, and/or stretching of cloth face coverings may influence the pore characteristics and subsequent filtering efficiency.24
由于目前缺乏N95呼吸器，研究人员已经调查了消毒和再利用的潜力，尽管一般指南不支持在正常情况下重复使用此类设备。28,29Scientists have identified that certain disinfecting methods such as autoclaving, >70% alcohol, chlorine-based disinfectants, and high temperature dry heat treatments at 165°C, reduce the filtration efficiency of N95 respirators. Instead, disinfection methods such as dry heat at 70°C, boiling water vapor, vaporous hydrogen peroxide, and ultraviolet light treatments appear more promising to maintain function in emergency circumstances associated with equipment shortages.29.30
Opportunity To Define New Standards
Although PPE has entered the common language, the associated regulatory definitions are not well understood. Navigating the regulatory requirements for PPE can a be daunting and time-consuming undertaking. But even with these challenges, there is opportunity for the textile community to participate in defining new standards and specifications for face coverings. PPE and surgical masks have specific performance and regulatory requirements that are overseen by governmental entities or other certifying agencies. On the other hand, DIY face coverings that are currently recommended by the CDC do not have performance requirements and are not regulated. Recent publications provide useful information on the important aspects of fabric construction and filtration performance for face coverings. They show that fiber type, fiber geometry and fabric construction play an important role in performance and comfort, and that there is an opportunity to systematically describe textile characteristics that make this possible.
References:
* SARS-CoV-2 is the name that the World Health Organization has given to the virus that causes the COVID-19 disease. See https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/naming-the-coronavirus-disease-(covid-2019)-and-the-virus-that-causes-it
1 The authors are consultants in the Polymer Science and Health Science practices at Exponent, Inc., a science and engineering consulting firm. This publication was authored by employees of Exponent, Inc. No portion of this publication has been funded or paid for by external sources.
2 For the purposes of this article, “protective coverings” means textiles that cover a portion of the user’s body that may reduce the risk of transmitting or contracting and infection from SARS-CoV-2 or other infectious agents. This includes Personal Protective Equipment (PPE) regulated by governmental agencies in workplaces and general coverings (e.g., face coverings) recommended by other agencies, such as the CDC. PPE use and effectiveness as it is associated with SARS-CoV-2 transmission is still under study in the scientific community.
3“有关使用布面覆盖物的建议，尤其是在基于社区的重大传播区域”的疾病控制与预防中心，审查于2020年4月3日，www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover.html。2020年4月21日访问。
4 https://www.osha.gov/SLTC/personalprotectiveequipment/
5 https://www.fda.gov/about-fda/fda-basics/what-does-fda-regulate
6 https://www.cdc.gov/niosh/about/default.html
7 N95呼吸器依靠复杂的聚合物纤维排列，静态电荷以及对佩戴者的紧密定制拟合。
8 “Surgical N95 vs. Standard N95 – Which to Consider?” 3M Personal Safety Division Technical Bulletin, Revision 2, March 2020. multimedia.3m.com/mws/media/1794572O/surgical-n95-vs-standard-n95-which-to-consider.pdf. Accessed 29 April 2020.
9 “Key Differences Between Respirators and Masks” 3M Personal Safety Division, April 2014. multimedia.3m.com/mws/media/956213O/differences-between-respirators-and-masks.pdf?fn=Respirator%20vs%20Surgical%20Mask%20flye. Accessed 29 April 2020.
10 “Infection Prevention Solutions – Face Masks and Respirators” 3M Healthcare. multimedia.3m.com/mws/media/312703O/masks-and-respirators-tri-fold-brochure-eng.pdf. Accessed 29 April 2020
11“内容详细信息21 CFR 878.4040 - 外科服装”美国政府出版社，www.govinfo.gov/app/app/details/cfr-2004-title21-vol8/cfr8/cfr-2004-title21-vol21-vol8-sec878-4040/summary。2020年4月29日访问
12“手术面具，手术N95呼吸器和工业N95呼吸器的比较”2020年4月20日访问
13 Desai, Angela and Mehrotra, Preeti. “Medical Masks.” JAMA Network, 4 March 2020. 10.1001/jama.2020.2331. Accessed 14 April 2020
14 https://www.osha.gov/sltc/personalprotectiveequipment/standards.html
15 Enforcement Policy for Face Masks and Respirators During the Coronavirus Disease (COVID-19) Public Health Emergency (Revised), April 2020.
16 “Personal Protective Equipment for Infection Control” U.S. Food & Drug Administration, 10 February 2020, www.fda.gov/medical-devices/general-hospital-devices-and-supplies/personal-protective-equipment-infection-control. Accessed 29 April 2020.
17本高Reza费萨尔,et al。”面具的使用respirators to prevent transmission of influenza: a systematic review of the scientific evidence.” Influenza and other respiratory viruses 6.4 (2012): 257-267.
18 https://www.cdc.gov/niosh/npptl/topics/respirators/pt84abs2.html
19 ANSI/ISEA Z87.1-2015, American National Standard For Occupational And Educational Personal Eye And Face Protection Devices.
20 ANSI/ASSP Z88.2-2015，呼吸保护的做法。
21 ASTM F2100-19, Standard Specification for Performance of Materials Used in Medical Face Masks.
22 Jansen, K. “Why the best material for a homemade coronavirus face mask is hard to identify?” Chemical & Engineering News April 2020. Available at: https://cen.acs.org/biological-chemistry/infectious-disease/best-material-homemade-coronavirus-face/98/web/2020/04
23 Qin, Yimin, ed. Medical textile materials. Woodhead Publishing, 2015.
24 Neupane, Bhanu Bhakta, et al. “Optical microscopic study of surface morphology and filtering efficiency of face masks.” PeerJ 7 (2019): e7142.
25 National Academies of Sciences, Engineering, and Medicine. “Rapid Expert Consultation on the Effectiveness of Fabric Masks for the COVID-19 Pandemic.” The National Academies Press (2020) 10.17226/25776.
26 Davies, Anna, et al. “Testing the efficacy of homemade masks: would they protect in an influenza pandemic?” Disaster medicine and public health preparedness 7.4 (2013): 413-418.
27 Neupane, Bhanu Bhakta, et al. “Optical microscopic study of surface morphology and filtering efficiency of face masks.” PeerJ 7 (2019): e7142.
28“ 2019年冠状病毒病（COVID-19）公共卫生紧急情况下的消毒剂，消毒装置和空气净化器的执法政策。工业与食品药品监督管理人员指南”美国食品和药物管理局，2020年3月。
29 “Decontamination and Reuse of Filtering Facepiece Respirators.” Centers for Disease Control and Prevention, reviewed 9 April 2020. www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html. Accessed 29 April 2020
30 Price, Amy and Chu, Larry. “What are good ways to address the shortage of face masks by anesthesiologists?” Stanford Medicine via Learnly (March 2020)
Editor’s Note: Dr. Davis Lee is senior managing scientist, Dr. Erin Kirkpatrick is managing scientist, Dr. A. Sydney Gladman is manager, and Dr. Emily Fitzharris is associate in the Polymer Science & Materials Chemistry practice of Exponent Inc. — a multi-disciplinary engineering and scientific consulting firm. Michael Posson is senior managing scientist and Dr. Mark Roberts is principal scientist at Exponent’s Health Sciences practice.
May/June 2020
