Quantification of Airborne Concentrations of Nano And Micro Scale Phosphor Particles In The Manufacturing environment by Spectrofluorometric Method

In this work, nanoscale luminescent materials dispersed in the air were collected and quantified by the fluorescence spectroscopy. A well-known phosphor; LuAG:Ce3+ was chosen as the model particle due to its strong, measurable and repeatable signal which can easily be excited by the blue light and emits at yellow wavelengths. The ionic liquid modified polymethylmethacrylate based filters were fabricated by electrospinning technique. Samples were collected by means of a vacuum pump from the laboratory environment during the grinding, weighing, transfer, washing, drying and packaging of the phosphorus particles, for different time intervals. The spectrofluorometric method was used for the quantification of the airborne concentration of the nano and microscale dusts. Presented method was also tested in terms of precision, LOD, LOQ, and stability. To the best of our knowledge, this is the first attempt to measure the airborne concentrations of the nano-scale luminescent phosphor particles and can easily be adopted for the quantification of other nanoscale- emitting particles in workplaces. Additionally, the offered design allows miniaturization since it is possible to excite the particles with cost-effective LED based light sources, integrate the system with fiber optics and detect the received optical response by photodiodes.

Airborne toxic exposure and pulmonary outcomes among petrochemical complex workers

Background Petrochemical workers are exposed to a variety of airborne toxic compounds which have been associated with increased risk for respiratory outcomes. However, long-term exposure to SO2, NO2, O3, H2S and NH3 in relation to spirometric parameters and self-reported respiratory problems is largely unknown. Methods Airborne concentration levels of SO2, NO2, O3, H2S and NH3 were collected from two fixed stations over a 3-year period in a petrochemical complex. We assessed spirometric parameters and respiratory symptoms in the petrochemical workers (n = 200) and in an unexposed group (n = 200). We calculated β-coefficients (β) and odds ratios (ORs) with 95% confidence intervals (CIs) before and after adjustment for covariates. Results The mean airborne pollution levels were 159 µg/m3 for SO2, 43 µg/m3 for NO2, 66 µg/m3 for O3, 6 µg/m3 for H2S, and 24 µg/m3 for NH3. We found a significant reduction in spirometric parameters among petrochemical workers compared to the unexposed: FEV1 (forced expiratory volume in 1s) (adjusted β -12; 95%CI -16, -7.64), FEV1/ FVC (forced vital capacity) (β -7.26; 95%CI -9.23, -5.28), and PEF (peak expiratory flow) (β -6.61; 95%CI -12, -0.76). Additionally, we observed higher adjusted risks for any respiratory symptom (OR 4.69; 95%CI 1.76, 12), mucus (OR 4.36; 95%CI 1.70, 11) and shortness of breath (OR 15; 4.95, 46) among petrochemical workers compared to the unexposed group. Conclusions Most measured airborne pollution levels were within the ambient recommendation levels. Still, long-term exposure to low level airborne pollutants, reduced FEV1, FEV1/FVC and PEF, and increased respiratory symptoms in Iranian petrochemical workers compared to unexposed controls.

Contribution of Visible Surface Mold to Airborne Fungal Concentration as Assessed by Digital Image Quantification

The rapid monitoring of total fungi, including air and surface fungal profiling, is an important issue. Here, we applied air and surface sampling, combined with digital image quantification of surface mold spots, to evaluate the contribution of surface fungi to airborne fungal concentrations. Cladosporium, Penicillium, Aspergillus, and yeast often appeared in the air or on wall surfaces during sampling. The indoor/outdoor concentration ratios (I/O ratios) demonstrated that the airborne concentrations of commonly found fungal genera outdoors were higher than those indoors (median I/O ratio = 0.65–0.91), excluding those of Penicillium and yeast. Additionally, the surface density (fungal concentration/area) of individual fungi showed no significant correlation with the airborne concentration, excluding that of Geotrichum. However, if a higher surface ratio (>0.00031) of mold spots appeared in the total area of an indoor environment, then the concentrations of Aspergillus and Geotrichum in the air increased significantly. Our results demonstrated that the airborne concentration of indoor fungi is significantly correlated with the outdoor concentration. A higher density of surface fungi does not necessarily contribute to a high fungal concentration in the air. In contrast to fungal density, quantification of the surface fungal area is recommended to assess the risk of surface fungi propelling into the air.

Quantifying the Tradeoff Between Energy Consumption and the Risk of Airborne Disease Transmission for Building HVAC Systems

Since the advent of the COVID-19 pandemic, there has been renewed interest in determining how the operation of building HVAC systems influences the risk of airborne transmission of disease. It has been established that combinations of increased ventilation, improved filtration, and other disinfection techniques can reduce the likelihood of transmission by removing or deactivating the airborne particles that potentially contain infectious material. However, when such guidance is general and qualitative in nature, it is extremely difficult for building managers to make informed decisions, as there is no quantitative information about how much risk reduction is provided. Furthermore, the actions that could be taken almost always require additional energy consumption by the HVAC system, and so in the absence of building-specific analysis, it is possible that chosen strategies might simply be wasting energy without providing meaningful reduction in transmission risk. To address this knowledge gap, we propose simplified steady-state models that can be used to quantify both the expected infection rate and the associated HVAC energy consumption that result from baseline operation and hypothetical changes. The transmission rate is modeled by considering the airborne concentration of infectious particles that would result from the activity-dependent respiration of an infector in the space, the physical dimensions of the space, and operation of the HVAC system. By formulating all disinfection mechanisms in terms of "equivalent outdoor air", a common basis is established for comparing and combining different strategies. Energy consumption can then be estimated by considering the change in HVAC variables (e.g., flow rates and temperatures) and applying standard models. To illustrate the insights provided by these models, we present examples of how the proposed analysis can be applied to specific spaces, highlighting the fact that underlying transmission risk (and thus also the energy-optimal disinfection strategies) can vary significantly from building to building and even from space to space within the same building. The overall goal is to empower building managers to fully assess the tradeoff between energy consumption and infection risk so that they can more effectively target their disinfection efforts and take actions that are consistent with current health and sustainability priorities.

Alternaria spores in the air of selected Polish cities in 2020

The study compares the course of the spore season of Alternaria in Bialystok, Cracow, Olsztyn, Piotrkow Trybunalski, Sosnowiec, Szczecin, Warsaw, and Wroclaw in 2020. The investigations were conducted using the volumetric method. Alternaria spore season was defined as the period in which 90% of the annual total catch occurred. The Alternaria season started first in Bialystok on May 19 and lasted on June 28 in Wroclaw. The highest airborne concentration of 1052 Alternaria spores/m3 was noted in Wroclaw on July 30. The highest annual sum of Alternaria spores (SPI) was observed in Warsaw (19 390 spores) and the lowest in Bialystok (5769 spores). Most days, the threshold concentration inducing symptoms in allergic persons occurred in Piotrków Trybunalski, Szczecin, and Warsaw.

Airborne Transmission of Virus-Laden Aerosols inside a Music Classroom: Effects of Portable Purifiers and Aerosol Injection Rates

The ongoing COVID-19 pandemic has shifted attention to the airborne transmission of exhaled droplet nuclei within indoor environments. The spread of aerosols through singing and musical instruments in music performances has necessitated precautionary methods such as masks and portable purifiers. This study investigates the effects of placing portable air purifiers at different locations inside a classroom, as well as the effects of different aerosol injection rates (e.g., with and without masks, different musical instruments and different injection modes). Aerosol deposition, airborne concentration and removal are analyzed in this study. It was found that using purifiers could help in achieving ventilation rates close to the prescribed values by the World Health Organization (WHO), while also achieving aerosol removal times within the Center of Disease Control and Prevention (CDC) recommended guidelines. This could help in deciding break periods between classroom sessions, which was around 25 minutes through this study. Moreover, proper placement of purifiers could offer significant advantages in reducing airborne aerosol numbers (offering orders of magnitude higher aerosol removal when compared to nearly zero removal when having no purifiers), and improper placement of the purifiers could worsen the situation. The study suggests the purifier to be placed close to the injector to yield a benefit, and away from the people to be protected. The injection rate was found to have an almost linear correlation with the average airborne aerosol suspension rate and deposition rate, which could be used to predict the trends for scenarios with other injection rates.

Douglas-fir beetle (Coleoptera: Curculionidae) response to single-point-source 3-methylcyclohex-2-en-1-one (MCH) releasers

The Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) (Coleoptera: Curculionidae) antiaggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH), has been used since 2000 to protect high-value trees and stands throughout western North America. Operational treatments involve placing individual releasers on a 12 m × 12 m grid throughout the area to be protected. In this study, six widely spaced trap lines were established with aggregation attractant–baited traps located 1, 3, 9, 27, and 81 m from a location where an operational MCH release device was alternately either present or absent, and changes in catches caused by the MCH device were assessed at all distances. Trap catches were suppressed by about 70% at one and three metres, by 50% at nine metres, by 30% at 27 m, and not at all at 81 m. Inhibition by the MCH device varied with distance (m) from the source according to the function 0.79 − 0.092x0.51 (R 2 = 0.986). Decline of attractant inhibition with distance from the MCH device was much less steep than would have been expected if catch inhibition had varied directly with the average airborne concentration of MCH.

Goosefoot – a plant that likes drought. The goosefoot family pollen season in 2019 in Poland, Hungary and Slovakia

Almost all the species of the Chenopodiaceae family present in our flora flower from July–August to the autumn. Unfortunately, allergies do not take a vacation. Warm, dry July and August weather should limit pollen emissions. However, similarly to most plants in dry habitats, goosefoot are well adapted to such conditions and does not provide even a short reprieve to pollen allergic patients. However, goosefoot pollen does not have a very large allergenic significance; despite the long pollen season lasting about 3 months, pollen concentrations in the air are low and very rarely exceed the concentration of 30 grains/m3. This study compares Chenopodiaceae pollen seasons in Poland, Hungary and Slovakia in 2019. The investigations were carried out using the volumetric method (Hirst type pollen sampler). Seasonal pollen index was estimated as the sum of daily average pollen concentrations in the given season. The pollen season ranges from June to September, depending on the geographical latitude. In Hungary and Slovakia there are much longer pollen seasons than in Poland. Pollen of goosefoot family contains the panallergen profilins, which are responsible for cross-reactivity among pollen-sensitized patients. In 2019 the pollen season of goosefoot started first in Hungary, in Kaposvar on June 7th and in Slovakia, in Žilina, on June 8th; in Poland pollen season started much later, on June 14th in Szczecin and Opole. At the latest, a pollen season ended in Nitria (Slovakia) on October 16th; in Kecskemet (Hungary) on October 3rd. In Poland the season ended much earlier than in Hungary and Slovakia already on August 25th. The differences of pollen season durations are considerable, the number of days ranged from 72 to 128. The dynamics of the pollen seasons of goosefoot family show similarities within a given country and considerable differences between these countries. However, the differences of the highest airborne concentration between the countries are not considerable (25 pollen grains/m3 in Poland, 49 pollen grains/m3 in Hungary, and 30 pollen grains/m3 in Slovakia. The maximum values of seasonal pollen count in Polish cities occurred between July 26th and August 29th, in Hungarian cities between August 27th and 30th, and in Slovakian cities between August 7th and 28th. Pollen season was characterized by extremely different total annual pollen SPI, in Poland from 116 to 360; in Hungary and Slovakia within the limits 290 to 980. Droughts that occur more frequently during the summer facilitate the spread of species of the goosefoot family due to the possibility of these plants gaining new habitats.

Implementation of a Particle Resuspension Model in a CFD Code: Application to an Air Ingress Scenario in a Vacuum Toroidal Vessel

During a loss of vacuum accident (LOVA), dust particles that will be present in the future tokamak ITER are likely to be resuspended, inducing a risk for explosion and airborne contamination. Evaluating the particle resuspension/deposition and resulting airborne concentration in case of a LOVA is therefore a major issue and it can be investigated by using a CFD code. To this end, this article presents the implementation of a resuspension model in a CFD code (ANSYS CFX) and its application to an air ingress in a vacuum toroidal vessel with a volume comparable to ITER one. In the first part of the article, the Rock’n Roll model and its operational version with the Biasi’s correlation is presented. The second part of the article will be devoted to the implementation of the Rock’n’Roll model in ANSYS CFX for constant friction velocities and its adaptation to non-constant friction velocities. Finally, the paper presents the simulations obtained on the particle resuspension for an air ingress scenario in a large vacuum vessel. This case is particularly interesting and non-intuitive because as the initial pressure is reduced, the particle behavior is different from that at atmospheric pressure. Further, a competition between airflow forces and gravitational force occurs, due to the low pressure environment, potentially restricting the resuspension, and the pressure influence also has to be taken into account in the particle transport and deposition (Nerisson, 2011). Three particle diameters were studied allowing to show the evolution of the resuspension with this parameter and to calculate dust resuspension rates and airborne fractions during the air ingress.