Ambient UFP Measurements – Options & Limitations of current measurement techniques

Air pollution due to particulate matter, especially ultrafine particles, and the related negative effects (health problems, economic damage) has become one of the major problems our society is faced with today. In order to be able to investigate and to assess the real exposition of the general public in a comprehensive way, the performance of precise and accurate measurements of particulate matter is an essential part of air pollution control. For the monitoring of ultrafine and engineered nanoparticles, typically Condensation Particle Counters and Differential Electric Mobility Sprectrometers are used. Depending on the aim of research the requirements on the monitoring instruments might be significantly different. Whereas for a general approach a low time resolution and higher detection limit might be acceptable, a more detailed analysis and source appointment desire detection limits down to 1nm, 1s time resolution or differentiation between volatile and non-volatile components. This presentation will show and discuss the possibilities and limitations of currently available instruments based on the examples from airport measurements or ship emissions

Reducing infection risk and optimization of airing concepts for indoor air quality by accurate aerosol and CO2 measurement

Since the outbreak of the SARS-CoV-2 pandemic and the findings about the virus transmission route through aerosols, indoor air quality is a major topic when it comes to efforts to contain the spread of SARSCoV- 2 in the population. Most calculations of infection risk, however, still rely on CO2 as a proxy for exhaled aerosols. This assumption is no longer valid when air filtration devices are used, arising the need to include actual measured aerosol concentration into the calculation of indoor infection risk. To close this gab, a version of Wells-Riley equation, extended to include the effect of air filtration into determination of reproductive number, is introduced and applied to measurement data from indoor air quality during school lessons. The results show, that taking only CO2 into account will overestimate the real infection risk from aerosols by 20% in the cases without air filtration and by 60% in the cases with air filtration. Furthermore, measurement results varied strongly between different classrooms. This indicates that general airing recommendation, as applied during these tests, are not enough to assure a healthy environment and more individual measurements are necessary.publishedVersio

Film growth rates and activation energies for core-shell nanoparticles derived from a CVD based aerosol process

Silica core-shell nanoparticles of about 60–120 nm with a closed outer layer of bismuth or molybdenum oxide of 1–10 nm were synthesized by an integrated chemical vapor synthesis/chemical vapor deposition process at atmospheric pressure. Film growth rates and activation energies were derived from transmission electron microscopy (TEM) images for a deposition process based on molybdenum hexacarbonyl and triphenyl bismuth as respective coating precursors. Respective activation energies of 123 ± 10 and 155 ± 10 kJ/mol are in good agreement with the literature and support a deposition mechanism based on surface-induced removal of the precursor ligands. Clean substrate surfaces are thus prerequisite for conformal coatings. Integrated aerosol processes are solvent-free and intrinsically clean. In contrast, commercial silica substrate particles were found to suffer from organic residues which hinder shell formation, and require an additional calcination step to clean the surface prior to coating. Dual layer core-shell structures with molybdenum oxide on bismuth oxide were synthesized with two coating reactors in series and showed similar film growth rates

The Aerosol Deposition Method: A Modified Aerosol Generation Unit to Improve Coating Quality

Owing to its ability to produce dense thick-films at room temperature directly from a ceramic powder, the Aerosol Deposition Method (AD) possesses a unique feature in ceramics processing. For this technology, the aerosol generation of particles is a decisive part of reliable process control. However, there has only been a small amount of work published addressing this topic. In this work, we compare the aerosolization and deposition behavior of a fluidized bed generator with an aerosol generator with the rotary brush principle. While film properties very much depend on deposition time for the fluidized bed generator, films produced with the brush generator show a constant film profile, and their film thickness correlates with the controllable aerosol concentration and the duration of deposition. This type of aerosol generation may improve the setup towards a more reliable AD process

Ischemic Heart Disease in Chronic Hepatitis B: A Danish Nationwide Cohort Study

OBJECTIVE: Data on the risk of ischemic heart disease (IHD) in patients with chronic hepatitis B virus (CHB) are conflicting. Our objective was to address the rate of IHD in patients with CHB compared with individuals without CHB (control-persons) from the general population. STUDY DESIGN AND SETTING: We conducted a cohort study of prospectively obtained data from Danish nationwide registries. We produced cumulative incidence curves and calculated the unadjusted incidence rate ratio (IRR) of IHD in persons with and without CHB. The adjusted association between having CHB and developing IHD was examined using a cause-specific Cox regression model. RESULTS: In total, 6472 persons with CHB and 62,251 age- and sex-matched individuals from the general population were followed for 48,840 and 567,456 person-years, respectively, during which 103 (1,59%) with CHB and 1058 (1,70%) control-persons developed IHD. The crude IRR was 1.13 (95% CI: 0.91–1.39). CHB did not have a statistically significant effect on the rate of IHD after adjusting for several confounding factors (adjusted hazard ratio: 0.96, 95% CI: 0.76–1.21). CONCLUSION: In this nationwide cohort study, we did not find any difference between rate of IHD in persons with CHB in comparison with the general population

Impact of Nanocomposite Combustion Aerosols on A549 Cells and a 3D Airway Model

The use of nanomaterials incorporated into plastic products is increasing steadily. By using nano-scaled filling materials, thermoplastics, such as polyethylene (PE), take advantage of the unique properties of nanomaterials (NM). The life cycle of these so-called nanocomposites (NC) usually ends with energetic recovery. However, the toxicity of these aerosols, which may consist of released NM as well as combustion-generated volatile compounds, is not fully understood. Within this study, model nanocomposites consisting of a PE matrix and nano-scaled filling material (TiO$_{2}$, CuO, carbon nano tubes (CNT)) were produced and subsequently incinerated using a lab-scale model burner. The combustion-generated aerosols were characterized with regard to particle release as well as compound composition. Subsequently, A549 cells and a reconstituted 3D lung cell culture model (MucilAir™, Epithelix) were exposed for 4 h to the respective aerosols. This approach enabled the parallel application of a complete aerosol, an aerosol under conditions of enhanced particle deposition using high voltage, and a filtered aerosol resulting in the sole gaseous phase. After 20 h post-incubation, cytotoxicity, inflammatory response (IL-8), transcriptional toxicity profiling, and genotoxicity were determined. Only the exposure toward combustion aerosols originated from PE-based materials induced cytotoxicity, genotoxicity, and transcriptional alterations in both cell models. In contrast, an inflammatory response in A549 cells was more evident after exposure toward aerosols of nano-scaled filler combustion, whereas the thermal decomposition of PE-based materials revealed an impaired IL-8 secretion. MucilAir™ tissue showed a pronounced inflammatory response after exposure to either combustion aerosols, except for nanocomposite combustion. In conclusion, this study supports the present knowledge on the release of nanomaterials after incineration of nano-enabled thermoplastics. Since in the case of PE-based combustion aerosols no major differences were evident between exposure to the complete aerosol and to the gaseous phase, adverse cellular effects could be deduced to the volatile organic compounds that are generated during incomplete combustion of NC

Comparing the Toxicological Responses of Pulmonary Air–Liquid Interface Models upon Exposure to Differentially Treated Carbon Fibers

In recent years, the use of carbon fibers (CFs) in various sectors of industry has been increasing. Despite the similarity of CF degradation products to other toxicologically relevant materials such as asbestos fibers and carbon nanotubes, a detailed toxicological evaluation of this class of material has yet to be performed. In this work, we exposed advanced air–liquid interface cell culture models of the human lung to CF. To simulate different stresses applied to CF throughout their life cycle, they were either mechanically (mCF) or thermo-mechanically pre-treated (tmCF). Different aspects of inhalation toxicity as well as their possible time-dependency were monitored. mCFs were found to induce a moderate inflammatory response, whereas tmCF elicited stronger inflammatory as well as apoptotic effects. Furthermore, thermal treatment changed the surface properties of the CF resulting in a presumed adhesion of the cells to the fiber fragments and subsequent cell loss. Triple-cultures encompassing epithelial, macrophage, and fibroblast cells stood out with an exceptionally high inflammatory response. Only a weak genotoxic effect was detected in the form of DNA strand breaks in mono- and co-cultures, with triple-cultures presenting a possible secondary genotoxicity. This work establishes CF fragments as a potentially harmful material and emphasizes the necessity of further toxicological assessment of existing and upcoming advanced CF-containing materials

Impact of the 2021 La Palma volcanic eruption on air quality: Insights from a multidisciplinary approach

The La Palma 2021 volcanic eruption was the first subaerial eruption in a 50-year period in the Canary Islands (Spain), emitting ~1.8 Tg of sulphur dioxide (SO2) into the troposphere over nearly 3 months (19 September-13 December 2021), exceeding the total anthropogenic SO2 emitted from the 27 European Union countries in 2019. We conducted a comprehensive evaluation of the impact of the 2021 volcanic eruption on air quality (SO2, PM10 and PM2.5 concentrations) utilising a multidisciplinary approach, combining ground and satellite-based measurements with height-resolved aerosol and meteorological information. High concentrations of SO2, PM10 and PM2.5 were observed in La Palma (hourly mean SO2 up to ~2600 µg m-3 and also sporadically at ~140 km distance on the island of Tenerife (> 7700 µg m-3) in the free troposphere. PM10 and PM2.5 daily mean concentrations in La Palma peaked at ~380 and 60 µg m-3. Volcanic aerosols and desert dust both impacted the lower troposphere in a similar height range (~ 0–6 km) during the eruption, providing a unique opportunity to study the combined effect of both natural phenomena. The impact of the 2021 volcanic eruption on SO2 and PM concentrations was strongly influenced by the magnitude of the volcanic emissions, the injection height, the vertical stratification of the atmosphere and its seasonal dynamics. Mean daily SO2 concentrations increased during the eruption, from 38 µg m-3 (Phase I) to 92 µg m-3 (Phase II), showing an opposite temporal trend to mean daily SO2 emissions, which decreased from 34 kt (Phase I) to 7 kt (Phase II). The results of this study are relevant for emergency preparedness in all international areas at risk of volcanic eruptions; a multidisciplinary approach is key to understand the processes by which volcanic eruptions affect air quality and to mitigate and minimise impacts on the population.The authors also acknowledge the support from ACTRIS and ACTRIS-Spain, the Spanish Ministry of Science and Innovation and the support from the European Union H2020 program through the following projects (PID2019-104205GB-C21/AEI/10.13039/501100011033, EQC2018-004686-P, PID2019-103886RB-I00/AEI/10.13039/501100011033 and PID2020- 521-118793GA-I00) and programs (GA No. 654109, 778349, 871115, 101008004 and 101086690). Research activities of the CSIC staff during the eruption were funded by CSIC through the CSIC-PIE project with ID numbers PIE20223PAL009 and PIE20223PAL013 (Real Decreto 1078/2021, de 7 de diciembre). Part of this study was performed within the framework of the project AERO-EXTREME (PID2021-125669NBI00) funded by the Spanish State Research Agency (AEI) and ERDF funds.Peer ReviewedPostprint (published version

Exhaled Aerosols in SARS-CoV-2 Polymerase Chain Reaction-Positive Children and Age-Matched-Negative Controls

BackgroundChildren and adolescents seem to be less affected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease in terms of severity, especially until the increasing spread of the omicron variant in December 2021. Anatomical structures and lower number of exhaled aerosols may in part explain this phenomenon. In a cohort of healthy and SARS-CoV-2 infected children, we compared exhaled particle counts to gain further insights about the spreading of SARS-CoV-2.Materials and MethodsIn this single-center prospective observational trial, a total of 162 children and adolescents (age 6–17 years), of whom 39 were polymerase chain reaction (PCR)-positive for SARS-CoV-2 and 123 PCR-negative, were included. The 39 PCR-positive children were compared to 39 PCR-negative age-matched controls. The data of all PCR-negative children were analyzed to determine baseline exhaled particle counts in children. In addition, medical and clinical history was obtained and spirometry was measured.ResultsBaseline exhaled particle counts were low in healthy children. Exhaled particle counts were significantly increased in SARS-CoV-2 PCR-positive children (median 355.0/L; range 81–6955/L), compared to age-matched -negative children (median 157.0/L; range 1–533/L; p < 0.001).ConclusionSARS-CoV-2 PCR-positive children exhaled significantly higher levels of aerosols than healthy children. Overall children had low levels of exhaled particle counts, possibly indicating that children are not the major driver of the SARS-CoV-2 pandemic.Trial Registration[ClinicalTrials.gov], Identifier [NCT04739020]