Particle Concentrations in Occupational Settings Measured with a Nanoparticle Respiratory Deposition (NRD) Sampler

Abstract

There is an increasing need to evaluate concentrations of nanoparticles in occupational settings due to their potential negative health effects. The Nanoparticle Respiratory Deposition (NRD) personal sampler was developed to collect nanoparticles separately from larger particles in the breathing zone of workers, while simultaneously providing a measure of respirable mass concentration. This study compared concentrations measured with the NRD sampler to those measured with a nano Micro Orifice Uniform-Deposit Impactor (nanoMOUDI) and respirable samplers in three workplaces. The NRD sampler performed well at two out of three locations, where over 90% of metal particles by mass were submicrometer particle size (a heavy vehicle machining and assembly facility and a shooting range). At the heavy vehicle facility, the mean metal mass concentration of particles collected on the diffusion stage of the NRD was 42.5 ± 10.0 µg/m3, within 5% of the nanoMOUDI concentration of 44.4 ± 7.4 µg/m3. At the shooting range, the mass concentration for the diffusion stage of the NRD was 5.9 µg/m3, 28% above the nanoMOUDI concentration of 4.6 µg/m3. In contrast, less favorable results were obtained at an iron foundry, where 95% of metal particles by mass were larger than 1 µm. The accuracy of nanoparticle collection by NRD diffusion stage may have been compromised by high concentrations of coarse particles at the iron foundry, where the NRD collected almost 5-fold more nanoparticle mass compared to the nanoMOUDI on one sampling day and was more than 40% different on other sampling days. The respirable concentrations measured by NRD samplers agreed well with concentrations measured by respirable samplers at all sampling locations. Overall, the NRD sampler accurately measured concentrations of nanoparticles in industrial environments when concentrations of large, coarse mode, particles were low.

Nanoparticle exposure and hazard in the ceramic industry: an overview of potential sources, toxicity and health effects

“…In turn, personal equipment allows to monitor exposure levels in worker's breathing zone and are small and lightweight enough to be carried over an eight-hour shift, without compromising any activity carried out by the worker (Asbach et al, 2017;Tsai et al, 2012). Generally, personal sampling is considered the preferred method since it provides an accurate representation of the worker's exposure regarding inhalable, thoracic or respirable particle fractions (Stebounova et al, 2018). Table 2 presents a general overview of the existing methods and available instrumentation for ANP quantification.…”

Size, composition, morphology, and health implications of airborne incidental metal-containing nanoparticles

“…A heavy vehicle machining and assembly center and an iron foundry were selected based on the similarities in the composition of particulate matter: Fe, Cu and Mn that were detected in a preliminary study at both sites. (45) The machining center produces construction and forestry equipment. Metal and metal oxide PM including nanoparticles were generated by robotic and manual metal inert gas (MIG) welding as well as metal parts grinding at this site.…”

“…In both locations, sampling was performed during three days using a field sampling cart placed in multiple areas of interest as described in detail previously. (45) Size-resolved analysis of the INPs was carried out using the nano-MOUDI (Model 125-R, MSP Corporation, Shoreview, MN). The nano-MOUDI was operated at 10 L/min with 13 greased polycarbonate (PC) substrates (0.2 μm, 47 mm, Sterlitech Corporation, Kent, WA) as previously reported.…”

“…These sites were selected due to the significant concentration of Fe, Mn and Cu found during a recent assessment of INPs exposure levels. (45) A FP-XRF was employed for on-site chemical characterization of metal-containing aerosol. (43) An off-site single-particle analysis was then performed to characterize primary particle morphology, composition and agglomerate status of INPs found in these two settings.…”

Recent Advances in Occupational Exposure Assessment of Aerosols

“…The effective deposition to the foam was tested using sodium chloride aerosol, and up to 19 mg loading of metal fume was generated from welding rods using spark discharge. Field studies included testing against a device providing aerosol size distributions in three workplace situations [78]. Good correlations were found in the two workplaces (a heavy vehicle machining and assembly facility and a shooting range) where the aerosol was not dominated by large particles, but the correlation was not so good at an iron foundry where 95% of the particles were >1 µm aerodynamic equivalent diameter.…”