High-volume evacuation mitigates viral aerosol spread in dental procedures.

Dental healthcare personnel (DHCP) are subjected to microbe-containing aerosols and splatters in their everyday work. Safer work conditions must be developed to ensure the functioning of the healthcare system. By simulating dental procedures, we aimed to compare the virus-containing aerosol generation of four common dental instruments, and high-volume evacuation (HVE) in their mitigation. Moreover, we combined the detection of infectious viruses with RT-qPCR to form a fuller view of virus-containing aerosol spread in dental procedures. The air-water syringe produced the highest number of aerosols. HVE greatly reduced aerosol concentrations during procedures. The air-water syringe spread infectious virus-containing aerosols throughout the room, while other instruments only did so to close proximity. Additionally, infectious viruses were detected on the face shields of DHCP. Virus genomes were detected throughout the room with all instruments, indicating that more resilient viruses might remain infectious and pose a health hazard. HVE reduced the spread of both infectious viruses and viral genomes, however, it did not fully prevent them. We recommend meticulous use of HVE, a well-fitting mask and face shields in dental procedures. We advise particular caution when operating with the air-water syringe. Due to limited repetitions, this study should be considered a proof-of-concept report.

Elemental analysis of single ambient aerosol particles using laser-induced breakdown spectroscopy.

Analysing the composition of aerosol particles is essential when studying their health effects, sources and atmospheric impacts. In many environments the relevant particles occur in very low concentrations, meaning that their analysis requires efficient single particle techniques. Here we introduce a novel method to analyse the elemental composition of single aerosol particles sampled directly from the aerosol phase using size amplification aided aerosol charging (SAAC), linear electrodynamic quadrupole (LEQ) and laser-induced breakdown spectroscopy. We present results of the charging and focusing efficiencies of the SAAC and of the LEQ, and a proof-of-concept of the analysis method. The proof-of-concept test series was conducted with particle diameters down to 300 nm, sampled directly from the aerosol phase. The method shows unprecedented performance for spectroscopic submicron particle analysis from arbitrarily low concentrations and has exceptional potential for a portable analysis platform for various applications in the field of aerosol research.

Traffic is a major source of atmospheric nanocluster aerosol.

In densely populated areas, traffic is a significant source of atmospheric aerosol particles. Owing to their small size and complicated chemical and physical characteristics, atmospheric particles resulting from traffic emissions pose a significant risk to human health and also contribute to anthropogenic forcing of climate. Previous research has established that vehicles directly emit primary aerosol particles and also contribute to secondary aerosol particle formation by emitting aerosol precursors. Here, we extend the urban atmospheric aerosol characterization to cover nanocluster aerosol (NCA) particles and show that a major fraction of particles emitted by road transportation are in a previously unmeasured size range of 1.3-3.0 nm. For instance, in a semiurban roadside environment, the NCA represented 20-54% of the total particle concentration in ambient air. The observed NCA concentrations varied significantly depending on the traffic rate and wind direction. The emission factors of NCA for traffic were 2.4·1015 (kgfuel)-1 in a roadside environment, 2.6·1015 (kgfuel)-1 in a street canyon, and 2.9·1015 (kgfuel)-1 in an on-road study throughout Europe. Interestingly, these emissions were not associated with all vehicles. In engine laboratory experiments, the emission factor of exhaust NCA varied from a relatively low value of 1.6·1012 (kgfuel)-1 to a high value of 4.3·1015 (kgfuel)-1 These NCA emissions directly affect particle concentrations and human exposure to nanosized aerosol in urban areas, and potentially may act as nanosized condensation nuclei for the condensation of atmospheric low-volatile organic compounds.

Fluorescence cross sections of bioaerosols and suspended biological agents.

Laser-induced fluorescence is used to investigate fluorescence properties of unwashed Bacillus thuringiensis and Bacillus subtilis spores, ovalbumin, and washed bacteriophage MS2. A fluorescence detector is calibrated to obtain absolute fluorescence cross sections. Fluorescence maps of biological aerosols and suspensions are measured at a wide excitation range from 210 to 419 nm and a wide detection range from 315 to 650 nm. The dominant features of the measured spectra are the amino acid peaks, having excitation maxima at 220 and 280 nm. The peaks are similar for the bacterial spores, both for aerosols and suspensions, whereas the peaks are shifted toward the shorter emission wavelengths for the suspended ovalbumin and MS2. Moreover, the fluorescence emission, excited above 320 nm is more intensive for the aerosols than the suspensions.