Face shield
A face shield is a type of personal protective equipment (PPE) comprising a transparent visor affixed to a headband, helmet, or frame, intended to shield the wearer's face—including eyes, nose, and mouth—from hazards such as splashes, sprays, flying particles, and chemical irritants.[1][2] Face shields provide barrier protection for the facial area and associated mucous membranes but are classified as secondary PPE, requiring primary eye protection like safety glasses underneath to address gaps in coverage.[3][4] They are employed across sectors including manufacturing, construction, laboratory work, and healthcare to mitigate risks from mechanical impacts, biological fluids, and environmental contaminants.[5][6] In infection control contexts, face shields reduce short-term exposure to large aerosol droplets from coughs or splatters, as demonstrated in controlled experiments where they blocked substantial portions of simulated infectious particles.[7][8] However, their efficacy diminishes over time due to aerosol leakage around the bottom and sides, rendering them inadequate as standalone respiratory barriers against fine airborne pathogens, with studies showing inferior performance to masks or respirators for source control and sustained filtration.[2][9][10]Definition and Design
Core Components and Functionality
Face shields consist of three primary components: a transparent visor, a supportive frame or headgear, and a suspension or attachment system. The visor, typically constructed from impact-resistant polycarbonate or similar polymers, forms the main protective barrier extending across the forehead to below the chin, providing full facial coverage.[2] The frame, often made of adjustable plastic or metal, secures the visor and includes a headband or straps that wrap around the head for stability.[11] Suspension elements, such as foam padding or ratchet mechanisms, enhance wearer comfort and allow for size adjustments to accommodate various head shapes.[12] These components function together to create a physical barrier shielding the face, eyes, nose, and mouth from hazards including flying debris, chemical splashes, and large infectious droplets.[13] Unlike goggles, face shields permit peripheral vision and do not press against the face, reducing discomfort during extended use, though they may require pairing with spectacles for complete eye sealing against smaller particles.[2] Compliance with ANSI/ISEA Z87.1 standards ensures the shield withstands specified impact levels, with markings indicating protection type, such as basic (Z87) or high-velocity impact resistance.[14] Functionality extends to mitigating splash and spray exposure in industrial, medical, and laboratory settings, where the curved or flat visor design deflects projectiles away from the user.[13] Anti-fog coatings on visors address condensation issues from humidity or breath, preserving visibility, while anti-scratch treatments prolong durability against abrasions.[12] However, face shields alone do not filter airborne contaminants like aerosols, necessitating integration with respirators for comprehensive respiratory protection.[2]Variations and Types
Face shields exhibit variations primarily in visor coverage, attachment mechanisms, material treatments, and integrated features to address diverse hazards such as impacts, splashes, and radiant energy. Full-coverage designs, extending from the forehead to the chin and often 8-10 inches in width, provide comprehensive barrier protection to the face, eyes, nose, and mouth mucous membranes, as required for high-risk exposures under ANSI/ISEA Z87.1-2020 standards for splash and impact resistance.[15][2] These differ from partial-coverage or half-shields, which prioritize lighter weight and mobility but offer reduced peripheral protection, typically limited to the eye and upper face area.[16] Attachment systems vary to enhance usability and compatibility with other PPE; headband-mounted shields use adjustable elastic or ratcheting straps for secure fit over helmets or alone, while cap-mounted or pivot/flip-up variants allow quick visor elevation for intermittent tasks without full removal.[17][16] Pivot designs, compliant with OSHA 29 CFR 1910.133 for secondary protection over primary eyewear like goggles, facilitate better airflow and reduce fogging during low-hazard intervals.[5][16] Feature-based variations include anti-fog coatings on polycarbonate or PET visors to maintain optical clarity in humid environments, ventilation slots for breathability without compromising seal integrity, and integrated magnification or shaded filters for precision work.[18] Disposable single-use shields, prevalent in medical settings for infection control, contrast with reusable models that withstand disinfection cycles up to 50 times while meeting impact ratings of Z87+ for high-velocity particles.[17][15] Specialized types, such as those with built-in eyewear frames or extra-wide visors (up to 12 inches), accommodate users needing prescription correction or broader splash deflection, though OSHA mandates they supplement—not replace—primary eye protection against fine particulates.[19][20] In industrial contexts, variations like shaded or high-heat-resistant shields integrate with welding helmets to filter ultraviolet and infrared radiation per ANSI Z87.1 drop and high-mass tests, enduring temperatures up to 200°C without deformation.[15] Lightweight PET iterations, weighing under 100 grams, prioritize extended wear in dynamic environments, differing from heavier polycarbonate models optimized for durability against 120 ft/s impacts.[21] All certified variants must bear permanent markings indicating compliance, ensuring traceability for hazard-specific selection as outlined in ISEA guidelines.[15]Historical Development
Early Innovations and Industrial Origins
The earliest known patent for a transparent protective face shield was granted in 1903 to Ellen Dempsey of Albany, New York, for a "sanitary face shield" intended to block disease-producing germs from inhalation during medical procedures.[2] This device represented an initial engineering solution for full-face barrier protection, utilizing a transparent material—likely glass—to maintain visibility while isolating the wearer from airborne contaminants, addressing causal risks of infection transmission through direct exposure.[22] Industrial adoption of face shields originated in the early 20th century, coinciding with rapid mechanization in manufacturing and the attendant rise in workplace injuries from particulate hazards, such as metal chips from machining, sparks from grinding, and splashes in chemical handling.[23] These environments demanded protective gear that preserved operational sight without impeding productivity, leading to adaptations of early transparent shields mounted on headbands or visors for use in metalworking, woodworking, and assembly lines. Pre-plastic versions often relied on tempered glass or wire-mesh overlays, which provided mechanical resistance but were prone to fogging, shattering, or reduced clarity under sustained use.[24] A pivotal advancement occurred in the 1930s with the commercialization of acrylic plastics, enabling lighter, more resilient shields. Rohm and Haas Company developed Plexiglas—a clear, shatter-resistant polymer—in facilities in Darmstadt, Germany (production began 1934), and Bristol, Pennsylvania (1936), initially for optical and enclosure applications before adapting to safety equipment.[25] This material's superior impact absorption and transparency reduced weight burdens on workers and minimized failure risks compared to glass, fostering wider integration into industrial protocols and contributing to declining facial injury rates as safety standards evolved.[26]20th-Century Advancements
In the early 20th century, face shields emerged as an extension of protective goggles in industrial settings, providing broader coverage against flying debris, sparks, and chemical splashes in sectors such as mining, manufacturing, and construction. Initially constructed from celluloid—a flammable early plastic—these shields offered superior face protection compared to spectacles alone, though their brittleness limited durability.[26][23] Mid-century advancements focused on improving ventilation and adjustability to address fogging and user comfort, particularly for welders and machinists. A 1953 patent for a vented face shield incorporated louvers to deflect dust while preventing steam buildup on the inner surface, enhancing visibility during prolonged use. Similarly, wartime and postwar patents, such as US2328687 granted in 1943, introduced mechanisms for attaching shields to caps with adjustable positioning relative to the wearer's face, facilitating integration with helmets.[27][28] By the 1960s, face shields saw adoption in law enforcement for riot control, as evidenced by the Philadelphia Police Department's deployment of polycarbonate models to shield officers from projectiles during street demonstrations. Regulatory standardization accelerated in the latter half of the century; the American National Standards Institute (ANSI) established eye and face protection criteria in the 1970s, while the Occupational Safety and Health Administration (OSHA) mandated their use under 29 CFR 1910.133 for hazards like molten metal and irritants, driving widespread industrial compliance and material shifts toward impact-resistant acetate and early polycarbonates.[25][5]COVID-19 Acceleration and Post-Pandemic Innovations
The COVID-19 pandemic triggered a surge in demand for personal protective equipment, prompting accelerated production of face shields through innovative manufacturing techniques. In early 2020, global shortages led manufacturers to pivot rapidly; for instance, JV Manufacturing retooled its operations within 10 days to produce over 13 million face shields by leveraging existing injection molding capabilities.[29] Similarly, MIT initiated mass production of disposable face shields using die-cutting machines, achieving rates of 50,000 units per day within weeks.[30] Institutions like the Wyss Institute at Harvard scaled up to deliver seven million face shields regionally by adapting local supply chains and collaborating with volunteers.[31] Additive manufacturing emerged as a key enabler for decentralized production, with 3D printing allowing hospitals, universities, and companies to fabricate face shields on-site. Boeing shipped initial batches of 3D-printed shields in April 2020, while Stratasys released open-source designs and guidance to facilitate widespread adoption.[32][33] Projects such as those at the Skolkovo Institute achieved daily outputs of thousands using light-transparent materials, and Dow introduced a simplified two-piece design to boost production efficiency, donating 100,000 units to Michigan healthcare providers.[34][35] These efforts highlighted the role of open-source sharing and rapid prototyping in addressing acute PPE needs, though 3D-printed variants often provided physical barriers with limitations in fluid resistance compared to traditional FDA-cleared options.[36] Post-pandemic innovations have focused on enhancing functionality and sustainability. Reusable designs, such as those from Fast Radius featuring interchangeable shields cleanable for up to two weeks, emerged to reduce waste and costs.[37] Smart face shields integrating sensors for monitoring physiological parameters like temperature and heart rate have been proposed for ongoing health tracking, including post-recovery from COVID-19 infections.[38] Advances in ergonomic, one-size-fits-all models with improved comfort and assembly without additional components reflect lessons from pandemic-era deployments, prioritizing ease of use in healthcare settings.[39] These developments underscore a shift toward multifunctional PPE resilient to future shortages.Materials and Manufacturing
Primary Materials Used
Face shields primarily consist of a transparent visor attached to a frame, with materials selected for optical clarity, durability, and hazard resistance. The visor, which provides the barrier against impacts, splashes, or aerosols, is most commonly manufactured from polycarbonate, a thermoplastic polymer valued for its high impact strength—up to 250 times that of glass—and ability to withstand temperatures up to 120°C without deforming.[40][41] Polycarbonate visors typically have a thickness of 1.5 mm for standard models, offering clear vision with minimal distortion while meeting ANSI Z87.1 impact standards.[41] Alternative visor materials include cellulose acetate and propionate, which provide superior chemical resistance against solvents and acids compared to polycarbonate, though they exhibit lower impact toughness.[2][42] Acetate, in particular, is favored for applications involving corrosive substances, as it resists degradation from exposure to oils and hydrocarbons, but it is more prone to scratching and fogging without coatings.[42] Polyethylene terephthalate glycol (PETG) or nylon may be used in specialized or 3D-printed visors for flexibility and reduced brittleness, though these are less prevalent in commercial production due to lower optical quality.[40] Frames are generally constructed from lightweight thermoplastics such as polypropylene or acrylonitrile butadiene styrene (ABS) to minimize user fatigue, with adjustable designs incorporating plastic hinges or ratcheting mechanisms for fit.[2] In industrial settings, frames may integrate metal brackets—often aluminum or steel—for attachment to hard hats, enhancing stability under high-heat or vibration conditions.[43] Straps or headbands typically employ elastic polymers like rubber or neoprene for secure, sweat-resistant fastening.[44] During the COVID-19 pandemic, frames were sometimes produced via additive manufacturing using polylactic acid (PLA), a biodegradable polyester derived from renewable resources, though this material offers inferior long-term durability compared to injection-molded thermoplastics.[45]Production Methods and Processes
Face shields are primarily manufactured using extrusion for the transparent visor material, followed by cutting and forming techniques, while frames and headbands are produced via injection molding. Polycarbonate or propionate sheets are extruded into flat rolls, providing optical clarity and impact resistance essential for protective barriers. These sheets are then precisely cut to visor dimensions using methods such as laser cutting, which allows for high precision and minimal waste on thin materials up to 3 mm thick, or die cutting for high-volume runs capable of processing thousands of units from flat stock. Injection molding forms the rigid frame components from thermoplastics like acrylonitrile butadiene styrene (ABS) or nylon, where molten polymer is injected into steel molds under pressures of 5,000 to 15,000 psi, enabling complex geometries like adjustable straps and anti-fog retention features; this process supports cycle times as low as 20-60 seconds per part in mass production.[45][30][46] Thermoforming serves as an alternative for visors requiring curvature to better conform to the face, involving heating extruded sheets to 150-180°C until pliable, then vacuum-forming over aluminum molds to achieve shapes with draw ratios up to 2:1, followed by trimming; this method excels in producing lightweight, disposable shields at rates of hundreds per hour per machine but may introduce optical distortions if cooling is uneven. Assembly integrates the visor with the frame using mechanical fasteners, ultrasonic welding, or adhesives like cyanoacrylate, ensuring a seal against splashes per standards such as ANSI Z87.1, with total production times for assembled units ranging from 40 seconds for flat-packed designs to several minutes for custom fits. Quality control includes impact testing at velocities up to 150 ft/s and fog resistance evaluations to verify durability.[47][48][49] In response to supply shortages during the COVID-19 pandemic, additive manufacturing via fused deposition modeling (FDM) 3D printing emerged for rapid prototyping and decentralized production of frames, using filaments like polyethylene terephthalate glycol (PETG) at layer heights of 0.2-0.3 mm to yield parts in 1-2 hours per unit; volunteer networks produced over 35,000 shields this way, though scalability was limited compared to injection molding, which output 80,000 units in equivalent efforts due to faster throughput. The U.S. Food and Drug Administration facilitated distribution of more than 500,000 3D-printed face shields by March 2021, prioritizing designs with open-source files for compatibility with consumer printers, but empirical assessments noted higher material costs (up to 5x traditional methods) and variability in fit from printer calibration differences. Post-pandemic, hybrid approaches combining 3D-printed prototypes with injection-molded scaling have informed standardized production, emphasizing biocompatibility and sterilization compatibility under ISO 10993 guidelines.[50][51][52]Primary Applications
Healthcare and Medical Use
Face shields serve as personal protective equipment (PPE) in healthcare settings to protect the eyes, nose, and mouth of medical personnel from splashes, droplets, and sprays of bodily fluids during patient interactions and procedures.[53] They are routinely used in environments involving potential exposure to infectious materials, such as surgical suites, dental clinics, and emergency departments.[11] In dentistry, face shields complement other PPE during aerosol-generating procedures like drilling or scaling, mitigating contamination from splatter that can reach the clinician's face.[54] Studies indicate that face shields reduce surface contamination on the wearer's face by acting as a physical barrier to larger particles, though their efficacy diminishes against finer aerosols without additional respiratory protection.[55] During the COVID-19 pandemic, face shields saw widespread adoption in healthcare facilities, often layered over surgical masks to enhance protection against SARS-CoV-2 transmission from respiratory droplets and aerosols.[56] A simulation study demonstrated that face shields reduced immediate viral exposure by approximately 96% for healthcare workers in close proximity (within 18 inches) to a coughing patient, outperforming masks in blocking direct forward projection of droplets.[56] In dental settings, combining face shields with masks significantly lowered the risk of coronavirus transmission during aerosol-producing treatments, with evidence showing decreased bioaerosol inhalation compared to masks alone.[57] However, randomized trials found that closed face shields paired with surgical masks were non-inferior to masks alone in preventing SARS-CoV-2 infections among high-exposure healthcare workers, though adherence and comfort influenced overall utility.[58] Empirical assessments highlight face shields' role in source control, deflecting exhaled droplets from the wearer, which is beneficial in procedural contexts like intubation or surgery where both patient and provider generate bioaerosols.[59] In oral surgery simulations, splatter contamination was notably higher on unprotected areas but reduced on face shields, underscoring their value in containing procedure-generated particles.[60] Guidelines from health authorities recommend face shields as adjunctive PPE rather than primary respiratory barriers, emphasizing integration with masks or respirators for comprehensive protection against airborne pathogens.[10]Industrial, Construction, and Welding
In industrial settings, face shields protect workers from hazards including flying particles, molten metal, chemical splashes, and impacts during operations such as machining, grinding, and metalworking. The Occupational Safety and Health Administration (OSHA) requires employers to provide eye and face protection under 29 CFR 1910.133 when employees face such risks, with devices required to meet ANSI/ISEA Z87.1 standards for impact and penetration resistance.[13][61] These shields typically feature a transparent visor extending from forehead to chin, often paired with underlying safety glasses to address gaps in coverage against lateral threats or fine dust.[62] In construction environments, face shields safeguard against debris from activities like chipping, sawing, drilling, and demolition, where large chips, fragments, or tools can strike the face at high velocities. OSHA's construction standard, 29 CFR 1926.102, mirrors general industry requirements by mandating compliant protection for exposed workers, emphasizing devices tested for high-velocity impacts under ANSI Z87.1-2020 protocols such as the drop-ball and high-mass tests.[63][15] Shields rated for splash and impact are preferred for tasks involving wet processes or overhead work, though they must be inspected regularly for scratches or fogging that could impair visibility and efficacy.[64] For welding and cutting, face shields provide critical defense against ultraviolet and infrared radiation, sparks, and slag expulsion, preventing flash burns, arc eye, and thermal injuries beyond what filtered helmets alone offer. ANSI Z49.1-2013 specifies that welding face protection must incorporate shade levels (e.g., shade 5 for gas welding) calibrated to arc intensity, while adhering to Z87.1 for overall durability against molten droplets tested at temperatures up to 1200°F.[65][66] Hand-held or flip-up shields with auto-darkening lenses enhance usability in multi-process welding, reducing downtime while maintaining protection; however, full-face coverage is essential during grinding or chipping phases of weld preparation to mitigate secondary hazards like airborne particulates.[67]Military, Law Enforcement, and Tactical
![US Navy sailor removing face shield from MCU-2-P gas mask][float-right] In military applications, face shields serve as protective visors integrated with ballistic helmets to safeguard against fragmentation, blasts, and blunt force trauma. The Batlskin Visor, developed for advanced combat helmets, features injection-molded polycarbonate with flawless optics, providing NIJ Level IIIA protection capable of stopping handgun rounds and smaller fragments while maintaining visibility.[68] Similarly, Ops-Core's Multi-Hit Handgun Face Shield attaches to tactical helmets like the FAST series, rated to withstand multiple impacts from 9mm threats, enhancing operator survivability in close-quarters engagements.[69] These systems prioritize modularity, allowing quick deployment or stowage to balance protection with operational mobility, though full-face ballistic coverage remains limited due to weight constraints exceeding 1-2 kg for visors alone.[70] Law enforcement utilizes face shields primarily in riot control and crowd management, where they form part of standardized protective ensembles to defend against thrown projectiles, liquids, and physical assaults. Riot face shields, often constructed from impact-resistant polycarbonate or acrylic, mount to helmets such as the ACH or PASGT variants and comply with NIJ Standard 0104.02, which mandates resistance to impacts from objects like 38-caliber lead slugs at specified velocities.[71] Models like the Paulson DK5 series incorporate anti-fog and anti-abrasion coatings, with V-50 fragmentation ratings ensuring durability in prolonged disturbances; for instance, the DK5-X.250AFS weighs 553 grams and provides a 15.2 cm by 0.64 cm viewing window optimized for peripheral awareness.[72] These shields enable officers to maintain visual contact while mitigating risks from debris or bodily fluids, as evidenced in deployments during civil unrest events.[73] Tactical operations in both military special forces and SWAT teams extend face shield use to high-threat scenarios such as hostage rescues, active shooter responses, and forced entries, where ballistic variants offer supplementary defense beyond standard eyewear. In SWAT applications, shields rated for NIJ IIIA protection integrate with plate carriers and helmets to counter handgun fire and shrapnel, with real-world deployments noted in raid operations as of 2025.[74] Polycarbonate materials dominate due to their high impact resistance—up to 250 times that of glass—and transparency, though limitations include reduced field of view compared to unprotected vision and vulnerability to rifle-caliber threats.[75] Overall, these applications emphasize layered protection, with face shields complementing rather than replacing primary body armor.[76]Effectiveness Assessment
Protection Against Physical and Chemical Hazards
Face shields provide secondary protection against physical hazards such as flying fragments, large chips, objects, and particles by forming a barrier that absorbs or deflects moderate impacts. Under ANSI/ISEA Z87.1-2020, compliant face shields must withstand high-velocity impact tests, including a 1/4-inch steel ball propelled at 150 feet per second (46 meters per second), demonstrating resistance to typical industrial projectiles without shattering or penetrating the visor.[15] [77] Laboratory evaluations of polycarbonate face shields have shown they maintain structural integrity against repeated low-to-moderate energy impacts, though performance degrades with material fatigue or improper fit.[78] However, face shields alone do not suffice for primary eye protection against impacts, as they permit peripheral exposure and lack the contoured seal of goggles; regulatory guidance mandates pairing them with ANSI Z87.1-certified spectacles or goggles to mitigate penetration risks from high-speed debris.[79] [64] In empirical impact testing, multi-layered protection combining face shields with underlying eyewear has proven superior, reducing facial injury risk by distributing force and preventing visor deflection onto the eyes, whereas standalone shields may fail against projectiles exceeding standard test energies, such as those above 50 joules.[80] Limitations include vulnerability to sharp or angular fragments that could chip the visor and inadequate shielding against ballistic threats or extreme velocities encountered in specialized environments like mining or demolition.[79] For chemical hazards, face shields act as a physical barrier against splashes, sprays, and larger droplets of hazardous liquids, safeguarding the face, eyes, and mucous membranes from corrosive or irritant substances. Propionate visors, valued for their chemical resistance, prevent penetration from acids, bases, and solvents during incidental spills, as verified through splash resistance protocols in standards like ANSI Z87.1, which require no liquid passage after exposure to simulated chemical jets.[81] [15] They are particularly effective in laboratory and industrial settings for gross exposures, where they reduce facial contamination by intercepting droplets greater than 100 micrometers, though efficacy diminishes with visor fogging or gaps at the edges.[2] Unlike sealed goggles, face shields offer no defense against chemical vapors, mists, or gases, which can bypass the open design; thus, they complement but do not replace respiratory apparatus or vapor-tight eyewear for airborne hazards.[82] Real-world assessments underscore their utility in preventing direct splash injuries but emphasize the need for immediate decontamination protocols, as residual liquids on the exterior pose secondary risks.[83]Empirical Evidence on Respiratory and Aerosol Filtration
Empirical studies demonstrate that face shields primarily block large respiratory droplets (>100 μm) expelled during coughing or sneezing, reducing short-term exposure for the wearer by deflecting particles away from the face. In a 2016 manikin-based experiment simulating cough aerosols, face shields decreased inhaled particle counts by up to 96% for large droplets when positioned 30 cm from the source, with efficacy dropping at greater distances due to dispersion.[7] However, protection diminishes rapidly beyond 45 cm, as smaller particles disperse laterally.[7] For smaller aerosols (1-5 μm, relevant to SARS-CoV-2 transmission), face shields exhibit substantial leakage due to their open perimeter, allowing airflow around the sides, bottom, and top. High-speed imaging and laser-based visualizations from 2020 revealed that aerosols from exhalation or speech curve around the shield's edges, bypassing filtration entirely and potentially contaminating nearby individuals.[84] A 2021 study using particle counters found face shields reduced inward aerosol penetration by only 23-52% for submicron particles, inferior to surgical masks (68-89%) owing to poor seal integrity.[85] As source control devices, face shields limit forward projection of cough-generated aerosols but fail to contain lateral or upward leakage effectively. Schlieren imaging experiments indicated shields trap <20% of expelled aerosols compared to masks, with particles escaping via gaps and traveling up to 1 meter sideways.[59] Combined with masks, shields add marginal aerosol filtration benefits, but standalone use yields total outward leakage efficiencies below 50% for viral-sized particles.[86] One countervailing study reported shields outperforming masks in blocking inhaled submicron particles (<1 μm) by 10-30% in static airflows, attributed to deflection rather than true filtration, though real-world movement exacerbates leaks.[10]| Particle Size Range | Face Shield Efficacy (Inward Protection) | Comparison to Surgical Mask | Key Limitation |
|---|---|---|---|
| >100 μm (large droplets) | 80-96% reduction in exposure | Comparable or slightly better for deflection | Distance-dependent; ineffective >45 cm[7] |
| 1-5 μm (aerosols) | 23-52% reduction | Inferior (masks: 68-89%) | Side/bottom leakage from poor fit[85] [84] |
| <1 μm (submicron) | Variable; up to 30% better deflection in controlled tests | Mixed; masks superior in dynamic scenarios | Airflow bypass, not filtration[10] [59] |