Search

Consumer-level 3D printers emit ultrafine and fine particles, though little is known about their chemical composition or potential toxicity. We report chemical characteristics of the particles in comparison to raw filaments and assessments of particle toxicity. Particles emitted from polylactic acid (PLA) appeared to be largely composed of the bulk filament material with mass spectra similar to the PLA monomer spectra. Acrylonitrile butadiene styrene (ABS), extruded at a higher temperature than PLA, emitted vastly more particles and their composition differed from that of the bulk filament, suggesting that trace additives may control particle formation. In vitro cellular assays and in vivo mice exposure all showed toxic responses when exposed to PLA and ABS-emitted particles, where PLA-emitted particles elicited higher response levels than ABS-emitted particles at comparable mass doses. A chemical assay widely used in ambient air-quality studies showed that particles from various filament materials had comparable particle oxidative potentials, slightly lower than those of ambient particulate matter (PM2.5). However, particle emissions from ABS filaments are likely more detrimental when considering overall exposure due to much higher emissions. Our results suggest that 3D printer particle emissions are not benign and exposures should be minimized.

Dimethyl sulfide (DMS) is a major source of sulfur to the marine boundary layer (MBL), and methanesulfonic acid (MSA) is one of its two main final oxidation products. MSA can participate in the nucleation and growth of aerosol particles, thereby affecting clouds and climate, and is used as a tracer of biological sulfur inputs. Unlike MSA, the other major oxidation product of DMS, sulfate, has several other sources, including volcanic and anthropogenic inputs. As a result, MSA to non-sea-salt sulfate (nss-sulfate) ratios are often used as proxies for biological activity; i.e., the MSA to nss-sulfate ratio in aerosol particles is used to estimate the marine biological contribution to nss-sulfate in the MBL. We present here a determination of the reactive uptake coefficient, γ, for the heterogeneous oxidation of MSA by hydroxyl radicals within deliquesced ammonium sulfate aerosol particles with an MSA mass fraction of 0.16 (a typical marine value) at room temperature. We find γ = 0.05 ± 0.03. For high ambien...

Brown carbon (BrC) consists of those organic compounds in atmospheric aerosols that absorb solar radiation and may play an important role in planetary radiative forcing and climate. However, little is known about the production and loss mechanisms of BrC in the atmosphere. Here, we study how the light absorptivity of BrC from wood smoke and secondary BrC generated from the reaction of ammonium sulfate with methylglyoxal changes under photolytic aging by UVA radiation in the aqueous phase. Owing to its chemical complexity, BrC is separated by molecular weight using size exclusion chromatography, and the response of each molecular weight fraction to aging is studied. Photolytic aging induced significant changes in the light absorptivity of BrC for all molecular weight fractions; secondary BrC was rapidly photoblenched, whereas for wood smoke BrC, both photoenhancement and photobleaching were observed. Initially, large biomass burning BrC molecules were rapidly photoenhanced, followed by slow photolysis. As a result, large BrC molecules dominated the total light absorption of aged biomass burning BrC. These experimental results further support earlier observations that large molecular weight BrC compounds from biomass burning can be relatively long-lived components in atmospheric aerosols, thus more likely to have larger impacts on aerosol radiative forcing and could serve as biomass burning tracers.