Microbiological Aerosol, Particulate Matter Concentrations and Antibiotic Resistant Staphylococcus spp. in the Premises of Poland’s Oldest Agricultural School

Bioaerosol, particulate matter concentration and antibiotic resistance of airborne Staphylococcus was assessed in animal and public premises (classroom, sports hall, horse stable, cowshed, newborn calf shed and outdoor background control site) of Poland’s oldest agricultural school. The concentration and size distribution of bacteria, fungi, actinomycetes and staphylococci were assessed with a six stage Andersen impactor. Particulate matter (PM10, PM4, PM2.5 and PM1) was determined using the DustTrak aerosol monitor. The Staphylococcus species were determined with MALDI-TOF mass spectrometry and antimicrobial resistance was assessed using disk diffusion. Bioaerosol concentrations differed significantly between sampling points, with the highest levels of all microorganisms occurring in the newborn calf shed. The proportion of respirable fraction exceeded 60% in all sites, indicating potential harmfulness to exposed people. Mean concentrations of particulate matter were the smallest in school rooms and the highest in the newborn calf shed. Neither particulate matter nor microbial aerosol exceeded threshold values for workplaces. Among thirty-four isolated staphylococcal strains, S. equorum (35%), S. succinus (26%) and S. xylosus (15%) were the most prevalent. Resistance to macrolides (erythromycin) and lincosamides (clindamycin) was the most frequent. One strain was methicillin-resistant. Farm animals are significant sources of bioaerosol and therefore attention should be paid with respect to maintaining appropriate sanitary conditions and hygiene of premises and animals.

Numerical Simulation of Container Breach and Airborne Release of Solids Due to Mechanical Insults

Throughout U.S. Department of Energy (DOE) complexes, safety engineers employ the five-factor formula to calculate the source term (ST) that includes parameters of airborne release fraction (ARF), respirable fraction (RF) and damage ratio (DR). Limited experimental data on fragmentation of solids, such as ceramic pellets (i.e., PuO2), and container breach due to mechanical insults (i.e., drop and forklift impact), can be supplemented by modeling and simulation using high fidelity computational tools to estimate these parameters. This paper presents the use of Sandia National Laboratories' SIERRA solid mechanics (SM) finite element code to investigate the behavior of the widely utilized waste container (such as 7A Drum) subject to a range of free fall impact and puncture scenarios. The resulting behavior of the container is assessed, and the estimates are presented for bounding DRs from calculated breach areas for the various accident conditions considered. This paper also describes a novel multiscale constitutive model recently implemented in SIERRA/SM that simulates the fracture of brittle materials such as PuO2 and determines ARF during the fracture process. Comparisons are made between model predictions and simple bench-top experiments.

Influence of Grit Size and Wood Species on the Granularity of Dust Particles during Sanding

Wood dust poses a threat to the health of employees and the risk of explosion and fire, accelerates the wear of machines, worsens the quality of processing, and requires large financial outlays for its removal. The aim of this study was to investigate the extent to which the grit size of sandpaper influences the size of the wood dust particles and the proportion of the finest particles which, when dispersed in the air, may constitute the respirable fraction. Six species of hardwood (beech, oak, ash, hornbeam, alder, and walnut), and three species of softwood (larch, pine, and spruce) were used in the research. While sanding the samples under the established laboratory conditions, the following were measured for two types of sandpapers (grit sizes P60 and P180): mean arithmetic particle size of dust and finest dust particles content (<10 µm). Based on the obtained results, we found that the largest dust particle sizes were obtained for alder, pine, and spruce; the smallest size of dust particles during sanding with both sandpapers was obtained for beech, hornbeam, oak, ash, larch, and walnut. The mean arithmetic particle sizes ranged from 327.98 µm for pine to 104.23 µm for hornbeam. The mean particle size of the dust obtained with P60 granulation paper was 1.4 times larger than that of the dust obtained with P180 granulation sandpaper. The content of the finest dust particles ranged from 0.21% for pine (P60 sandpaper) to 12.58% for beech (P180 sandpaper).The type of wood (hardwood or softwood) has a significant influence on the particle size and the content of the finest dust fraction.

Determination of phthalates in particulate matter and gaseous phase emitted in indoor air of offices

Phthalate esters (PAEs) are endocrine disrupters and can disrupt the functioning of different hormones, causing adverse effects on human health. Due to the potential exposure to phthalates in office rooms, their concentrations in the air of these premises after their renovation and furnishing were determined. The aim of the study was to determine the content of these compounds in the gas phase and adsorbed on the particles. Thus, the combined sampler with filters and adsorption tube was used for air sampling. Samples were analyzed by GC-MS. The gas fraction was dominated by dimethyl phthalate (DMP), diethyl phthalate (DEP), and the inhalable fraction by dibutyl phthalate (DBP) and 2-(diethylhexyl) phthalate (DEHP). The total concentration of phthalates in the respirable fraction in the furnished rooms was as much as 92% of the phthalates determined in the inhalable fraction. In the rooms immediately after renovation and those arranged and used by employees for 7 months, their concentration in the respirable fraction did not exceed 25% of the phthalates in the inhalable fraction. Phthalate concentration in the renovated rooms after 7 months of their usage dropped by 84% in relation to PAEs concentration in newly arranged rooms and by 68% in relation to the phthalate concentration in empty rooms.

Microbiological Air Quality in a Highschool Gym Located in an Urban Area of Southern Poland—Preliminary Research

The benefits of regular exercise include improved physical and mental health. The school gym is a particular micro-environment where students perform intensive physical training. The question is if there is an increased risk of microbiological contamination. This preliminary work studied the exposure of students to bacterial aerosol (BA) in a highschool gym located in an urban area of Southern Poland. A sampling of BA was undertaken with an Andersen six-stage impactor (ANDI). BA was identified using API (analytical profile index) tests. The BA concentrations were expressed as Colony Forming Units (CFU) per cubic metre of air. The results showed that before gym classes (BGC), the concentration of BA was 4.20 × 102 ± 49.19 CFU/m3, while during gym classes (DGC), the level of BA more than doubled (8.75 × 102 ± 121.39 CFU/m3). There was also an increase in the respirable fraction of BA (particles less than 3.3 µm). Before the start of the sports activities, respirable fraction accounted for 30% of the BA, while during physical education classes, this share increased to over 80%. Identification of BA species showed that the dominant group of bacteria in the indoor air of the gym BGC was Gram-positive rods (61%) and for DGC it was Gram-positive cocci (81%). We detected that one bacteria strain (Corynebacterium striatum) was classified into risk group 2 (RG2) according to Directive 2000/54/EC. Additionally, multi-antibiotic resistance (MAR) showed that among the isolated airborne bacteria, the highest antibiotic resistance was demonstrated by Staphylococcus epidermis (isolated DGC) and Pseudomonas sp. (isolated BGC). The quantitative and qualitative information on microbiological air quality (MIAQ) in the school gym indicates that the actions to improve indoor physical activity spaces are recommended.

Proposal for the risk analysis for silica exposure based on the respirable fraction dust

Crystalline silica is a natural chemical compound present in rocks, sand and soil. In industry, it is found in chemical products: cement, bricks, concrete... To measure the amount of silica a worker breathes, a dust sample must be taken from the respirable fraction. Due to the cost of chemical analysis of this fraction against silica, whose proportion is approximately 1:25, it is important to establish a methodology that allows an approximation of the risk calculation related to silica exposure, in order to reduce it. According to this, 63 data (2016-2019) were analysed, corresponding to measurements of the aforementioned dust with emphasis on silica belonging to industrial processes. The data were then analysed, and a statistically acceptable relationship was found for different industrial processes, resulting in a mathematical equation to determine the amount of silica, as a function of the amount of respirable fraction, with a statistical acceptance level.

Exposure Dose of Bacteria and Fungi in a Public Primary School in Beni Suef, Upper Egypt

Potential health risk due to the exposure of bacteria and fungi is mainly related to the concentration of respirable airborne bacteria and fungi in indoor environments. Schools buildings represent an important category of indoor environments. This study aimed to evaluate the concentration and size distribution of bacteria and fungi in classrooms of a public primary school in Beni Suef, Egypt. In addition, the indoor exposure dose (IED) of bacteria and fungi were estimated for children and teachers. A six-stage Andersen impactor was used for collecting the bacterial and fungal particles. Indoor average concentration of bacteria was 1120±458 CFU/m3 while the corresponding fungal concentration was 291±89 CFU/m3. Bacterial level is almost twice the World Health Organization guideline value of 500 CFU/m3 while the fungal level is underestimated. Respirable fraction (<5 µm), that can reach to the lower airways of the lung, of bacteria was 79% while the corresponding respirable fraction of fungi was 90% of the total concentration. The size distribution of bacteria was bimodal in nature and the fungal size distribution was unimodal with lower dispersion than bacteria. IED of bacteria was 211 CFU/kg and 70 CFU/kg for children and teachers, respectively. While the fungal IED was 55 CFU/kg and 18.2 CFU/kg for children and teachers, respectively.