The National Institute for Occupational Safety and Health (NIOSH) Nanotechnology Research Center (NTRC) has reached its 20-year milestone, marking sustained progress in protecting workers from engineered nanoparticles and biological aerosol particles. Among its ten critical nanotechnology topic areas, Engineering Controls and Personal Protective Equipment (PPE) has played a central role in advancing both scientific understanding and practical application of protective measures. PPE in this context encompasses respirators, gloves, and chemical protective clothing, all aimed at reducing occupational exposure to potentially hazardous nanomaterials.
The rapid commercialization of nanotechnology-based products has expanded global markets and intensified workplace use of engineered nanomaterials. This growth has heightened concerns about health risks associated with occupational exposure, prompting NIOSH researchers to develop laboratory and field-based guidance rooted in scientific evidence. Their work has produced national recommendations for respiratory protection and other PPE, ensuring that safety measures keep pace with evolving materials and manufacturing techniques.
Early investigations between 2005 and 2008 concentrated on evaluating respirator performance in the nano-sized particle range. This period saw increased attention to how respirators performed when challenged by particles far smaller than those typically encountered in industrial settings. Such research laid the groundwork for understanding filtration efficiency against nanoscale hazards.
From 2012 to 2015, studies progressed to testing respirators with human subjects under simulated workplace conditions. As noted in NIOSH’s 2013 Current Intelligence Bulletin 65, animal toxicological evidence indicated a broad spectrum of potential human health effects from engineered nanoparticle exposure. In response, researchers measured simulated workplace protection factors for N95® and P100® filtering facepiece respirators, as well as elastomeric half mask respirators, across particle sizes from 20 to 400 nanometers. This was the first effort to quantify respirator performance against nanoparticles in conditions mimicking actual work environments, and it revealed performance differences linked to filter series and efficiency levels. Vo et al. (2015) documented these findings, providing a benchmark for future respirator evaluations.
Advances in aerosol sampling technology from 2014 onward introduced portable instruments that were smaller and lighter than previous generations. NIOSH researchers developed a method, described by Vo et al. (2020), to test how these instruments could be carried during routine work and withstand the physical demands of occupational tasks, such as bending and reaching. This approach enabled direct measurement of respirator performance against aerosol particles in simulated workplace settings, expanding the practical toolkit for PPE assessment.
Respirator selection in many workplaces still relies on manufacturer recommendations or laboratory penetration data using spherical particles. However, elongated nanomaterials behave differently due to variations in rotation time, interception, and inertial impaction. Recognizing this, NIOSH researchers have outlined plans to develop a reliable aerosol testing method tailored to workplace nanomaterials, evaluate the effectiveness of NIOSH-approved® respirators under these conditions, and compare penetration results obtained through direct-reading instruments and elemental carbon analysis.
The body of work produced over two decades includes peer-reviewed publications that detail nanoparticle penetration through NIOSH-approved respirators, filtration performance against ultra-fine particles, and techniques for evaluating decontamination procedures for viral droplets on respirators. These studies have informed PPE guidelines and contributed to safer practices in industries where nanomaterial exposure is a concern.
Evanly Vo, PhD, DDS, Physical Scientist and NTRC-PPE Coordinator, Michael Bergman, MS, Biologist, and Ziqing Zhuang, PhD, General Engineer, have been among the key contributors driving this research forward. Their efforts underscore the importance of aligning PPE development with the unique challenges posed by advanced materials. As engineered nanomaterials continue to evolve in form and application, the work of the NTRC in engineering controls and PPE remains essential to safeguarding worker health.