Field Evaluation of N95 Filtering Facepiece Respirators on Construction Jobsites for Protection against Airborne Ultrafine Particles

Abstract

Exposure to high concentrations of airborne ultrafine particles in construction jobsites may play an important role in the adverse health effects among construction workers, therefore adequate respiratory protection is required. The performance of particulate respirators has never been evaluated in field conditions against ultrafine particles on construction jobsites. In this study, respiratory protection levels against ultrafine particles of different size ranges were assessed during three common construction related jobs using a manikin-based set-up at 85 L/min air flow rate. Two NanoScan SMPS nanoparticle counters were utilized for measuring ultrafine particles in two sampling lines of the test filtering facepiece respirator—one from inside the respirator and one from outside the respirator. Particle size distributions were characterized using the NanoScan data collected from outside of the respirator. Two models of N95 respirators were tested—foldable and pleated. Collected data indicate that penetration of all categories of ultrafine particles can exceed 5% and smaller ultrafine particles of <36.5 nm size generally penetrated least. Foldable N95 filtering facepiece respirators were found to be less efficient than pleated N95 respirators in filtering nanoparticles mostly at the soil moving site and the wooden building frameworks construction site. Upon charge neutralization by isopropanol treatment, the ultrafine particles of larger sizes penetrated more compared to particles of smaller sizes. Our findings, therefore, indicate that N95 filtering facepiece respirators may not provide desirable 95% protection for most categories of ultrafine particles and generally, 95% protection is achievable for smaller particles of 11.5 to 20.5 nm sizes. We also conclude that foldable N95 respirators are less efficient than pleated N95 respirators in filtering ultrafine particles, mostly in the soil moving site and the wooden building framework construction site.

Mask Material Filtration Efficiency and Mask Fitting at the Crossroads: Implications during Pandemic Times

“…Whereas some studies use a manikin headform with the full mask (Balazy et al, 2006a,b;He et al, 2013;Bahloul et al, 2014;Shakya et al, 2016;Adhikari et al, 2018;Kumar et al, 2020), other studies cut a portion of the mask/fabric and place it in a filter holder (Eshbaugh et al, 2008;Lin et al, 2017;Konda et al, 2020;Pei et al, 2020;Wang et al, 2020). Many studies use salt, e.g., NaCl (Eshbaugh et al, 2008;He et al, 2014;Lin et al, 2017;Pei et al, 2020), or polystyrene latex (PSL) spherical particles of defined sizes (Qian et al, 1997;Lee et al, 2005;Eshbaugh et al, 2008) to simulate particulate contaminants.…”

“…Many studies use salt, e.g., NaCl (Eshbaugh et al, 2008;He et al, 2014;Lin et al, 2017;Pei et al, 2020), or polystyrene latex (PSL) spherical particles of defined sizes (Qian et al, 1997;Lee et al, 2005;Eshbaugh et al, 2008) to simulate particulate contaminants. The particle concentration used in these experiments varies from hundreds to several tens of thousands of particles per cm 3 (Balazy et al, 2006a,b;Eshbaugh et al, 2008;He et al, 2014;Adhikari et al, 2018). A variety of flow rates were used in these tests (Eshbaugh et al, 2008;He et al, 2013;Bahloul et al, 2014;Adhikari et al, 2018), yet the most…”

“…The particle concentration used in these experiments varies from hundreds to several tens of thousands of particles per cm 3 (Balazy et al, 2006a,b;Eshbaugh et al, 2008;He et al, 2014;Adhikari et al, 2018). A variety of flow rates were used in these tests (Eshbaugh et al, 2008;He et al, 2013;Bahloul et al, 2014;Adhikari et al, 2018), yet the most…”

Comparison of the Filtration Efficiency of Different Face Masks Against Aerosols

“…Interestingly, such a particle size corresponds to the 300 nm particulate size threshold used for grading the filtration efficiency of masks (5) and the most penetrating particle size of single-filter masks (6). Moreover, in field tests, investigators have reported poor performance of N95 masks (7). A key reason for such a finding may have been poor mask seal afforded by N95 masks which could be prevented by elastomeric linings.…”

Assess the Performance against ETS and PM1 and Evaluate the Users’ Experiences of Comfort of Nasal Filters

“…In todays' workplace, filtering facepiece respirators (FFR) are frequently used by indoor/outdoor workers to reduce exposure to airborne particulate pollution (Chen et al, 2016;Adhikari et al, 2018). An air-purifying respirator such as the N95 FFR or the P100 FFR collects 95-99.9% of the most penetrating size aerosol, so wearing them in indoor/outdoor working areas can minimize exposure to air pollution.…”