This alternative microplastic extraction method employs ultrapure water, ultrasonication, and identification using complementary optical microscopy, SEM/EDS, FTIR, and RMS techniques.

The composition of wildfire smoke particulate matter (PM) was investigated during a 2018 smoke episode in the San Francisco Bay Area and compared to non-wildfire periods. Scanning electron microscopy (SEM) of passive PM samples deployed at four sites exhibited a higher concentration of submicron, spherical, carbonaceous PM (“tar balls”) during the wildfire period compared to the non-wildfire period. Coarse ash aluminosilicates and potassium bearing particles were enhanced as well. Disproportionately more UV light was absorbed by PM during the wildfire period than during the non-wildfire period, indicating a higher organic content consistent with the observed tar balls. An indoor PM sample from a residence operating a medium-efficiency furnace filter during the smoke episode exhibited fine, carbonaceous PM comparable to outdoors, but reduced coarse ash PM. Indoor/outdoor ratios for PM_2.5, PM_10-2.5, and PM₁₀ were 0.6, 0.1, and 0.5 respectively. SEM of the wildfire furnace filter revealed a greater proportion of tar balls compared to a non-wildfire filter. Relatively rare particles enriched in Cu, Zn, Sn and Pb were observed in wildfire samples, but not in non-wildfire samples. Higher concentrations of Cu, Zn, and Pb during the wildfire were confirmed by inductively coupled plasma mass spectrometry (ICP-MS) of the furnace filter. The use of low-cost passive samplers enabled rapid deployment at multiple locations and indoors and outdoors during the wildfire episode. These measurements suggest smoke impacts were regional in scale and similar across sites, though local variations in PM_2.5 magnitudes, particle types, and confounding by local sources were observed. Copyright © 2021 American Association for Aerosol Research

We characterized flame retardant (FR) morphologies and spatial distributions in 7 consumer products and 7 environmental dusts to determine their implications for transfer mechanisms, human exposure, and the reproducibility of gas chromatography-mass spectrometry (GC-MS) dust measurements. We characterized individual particles using scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS). Samples were screened for the presence of 3 FR constituents (bromine, phosphorous, non-salt chlorine) and 2 metal synergists (antimony and bismuth). Subsequent analyses of select samples by RMS enabled molecular identification of the FR compounds and matrix materials. The consumer products and dust samples possessed FR elemental weight percents of up to 36% and 31%, respectively. We identified 24 FR-containing particles in the dust samples and classified them into 9 types based on morphology and composition. We observed a broad range of morphologies for these FR-containing particles, suggesting FR transfer to dust via multiple mechanisms. We developed an equation to describe the heterogeneity of FR-containing particles in environmental dust samples. The number of individual FR-containing particles expected in a 1-mg dust sample with a FR concentration of 100ppm ranged from 1000 particles. The presence of rare, high-concentration bromine particles was correlated with decabromodiphenyl ether concentrations obtained via GC-MS. When FRs are distributed heterogeneously in highly concentrated dust particles, human exposure to FRs may be characterized by high transient exposures interspersed by periods of low exposure, and GC-MS FR concentrations may exhibit large variability in replicate subsamples. Current limitations of this SEM/EDS technique include potential false negatives for volatile and chlorinated FRs and greater quantitation uncertainty for brominated FR in aluminum-rich matrices.

Identifying the functional materials inside vaping devices can help inform efforts to understand risk. While nicotine E-cigarette components and metals have been characterized in several previous studies, the internal component compositions of tetrahydrocannabinol (THC) cartridge designs are not as well known. The 2019–20 e-cigarette or vaping product use associated lung injury (EVALI) outbreak has been associated with THC devices containing vitamin E acetate (VEA), possibly mediated by chemical reactions with internal cartridge components and high filament temperatures. We investigate the composition and internal components of 2019 EVALI patient-associated THC vaping devices compared to other THC and nicotine devices from 2016–19, specifically the metal, ceramic, and polymer components likely to be exposed to heat. To do this, we have disassembled forty-eight components from eight used and unused vaping devices under a microscope and analyzed them using X-ray fluorescence, scanning electron microscopy, and Fourier-transform infrared micro-spectroscopy. The two THC cartridges used by EVALI patients exhibited evidence of localized high temperatures, including charring of the ceramic heating elements and damaged wire surfaces. The newer THC cartridges possessed more ceramic and polymer insulation than older THC or nicotine devices. The combination of ceramics, metals, and high temperatures in newer THC cartridges is consistent with conditions hypothesized to produce VEA reactions during vaping. Nickel and chromium components were detected in all devices, and others contained copper, lead, tin, gold, silicon-rich rubbers, or fluorinated microplastics. These components have the potential to thermally degrade and volatilize if heated sufficiently. These findings do not imply that harmful exposures would occur under all usage conditions, and are most relevant to harm reduction efforts based on avoiding higher internal temperatures. This study was limited to a small sample of cartridges obtained from investigations. Future work should test more device types and internal temperatures under controlled usage conditions.