Respirable Particles Research Articles

Neuron-Specific Enolase as a Biological Marker for Welders' Pneumoconiosis.

The aim of the study is to investigate the relationship between serum neuron-specific enolase (NSE) and welders' pneumoconiosis, through chest x-ray and serum NSE. The exposed group included 37 welders. The nonexposed group included 38 administrative workers. Both groups underwent history taking, clinical examination, chest x-ray, serum chromium, and serum neuron-specific enolase. Air sampling was done for total suspended particles, respirable particles, and welding fumes. All the air samples were within the national threshold limit values. Chest x-ray abnormalities were found in eight welders (21.6%), and included reticular opacities, scattered nodules or ground-glass opacities. Serum chromium and NSE were significantly higher among welders. Serum NSE correlated positively with the duration of exposure and serum chromium level among welders. Serum NSE can be used as a biomarker for early detection of welders' pneumoconiosis.

The emission and physicochemical properties of airborne microplastics and nanoplastics generated during the mechanical recycling of plastic via shredding

This study examined the emission and physicochemical properties of microplastics and nanoplastics (MPs/NPs) generated during shredding, which is regularly used in mechanical recycling. Waste and new polyethylene terephthalate, polypropylene, and high-density polyethylene were investigated herein for a total of six categories. The concentration and size distribution of particles were measured using two spectrometer instruments, and morphology and elemental composition of emitted particles were analyzed with microscopy and spectroscopy. This study found that number concentrations in both submicron and micron sizes of respirable particles were 3–2910× higher during periods of shredding than pre-shredding background concentrations. Maximum concentrations of particles within 10–420 nm, across all six categories, ranged from 22,000- to 1,300,000-particles/cm3 during shredding, compared to average background levels of 700 particles/cm3. Maximum concentrations of particles within 0.3 to 10 μm, across all six categories, ranged from 24- to 2000-particles/cm3 during shredding, compared to average background levels of 2 particles/cm3. Waste plastics consistently generated higher emissions than their new counterparts, which is attributed to the labels, adhesives, and increased additives incorporated into the waste plastic. Morphology varied drastically between particles and an elemental composition analysis found that the samples consisted primarily of C and O, representing the polymer material, as well as Na, Mg, Al, Si, Cu, Cl, K, Ca, Ti, Fe, Rb, and Br representing additives, label, and other contaminates. The shredding of plastic has the potential to expose workers to elevated concentrations of airborne MPs/NPs, especially those between 10 and 100 nm.

Inhaler personalisation based on peak inspiratory flow (PIF) among dry powder inhaler users: a pilot randomised control trial (RCT) in COPD.

Dry powder inhalers (DPIs) are commonly used among patients with Chronic Obstructive Pulmonary Disease (COPD). These inhalers are breath-actuated, and require patients to generate sufficient peak inspiratory flow (PIF) to disaggregate the drug powder into respirable fine particles and deliver it to the lower airway tracts. Inhaler personalisation based on PIF among DPI users has not been studied in Malaysia, thus we conducted the present pilot study to determine the feasibility of conducting such research among COPD patients. This was an open-label pilot randomised control trial, conducted from June 2021-January 2022 at the respiratory clinic of Hospital Canselor Tuanku Muhriz, Universiti Kebangsaan Malaysia. Measurement of PIF was performed with In-Check DIAL G16 among adult COPD patients treated with DPI and had suboptimal PIF. Eligible subjects were randomised using block randomisation into two groups, either the interventional group or the control group. Twenty-two COPD patients fulfilled the study criteria and were randomised to intervention (n = 11) and control (n = 11) groups. For the interventional group, there were statistically significant improvements between baseline and at 12 weeks for both FEV1 and CAT scores. The mean (% predicted) FEV1 were 54.6 ± 20.4% and 56.6 ± 19.8% (p = 0.026), pre-and post-intervention. The mean CAT score at baseline was 24.4 ± 5.8 and reduced to 19.6 ± 4.4 at 12 weeks (p = 0.012). For the control group, the mean (% predicted) FEV1 at baseline was 58.0 ± 21.9% and 56.5 ± 20.7% at 12 weeks, with no statistical significance difference (p = 0.143). However, there was a statistically significant difference in CAT scores at baseline and 12 weeks, with a mean of 26.5 ± 6.1 and 23.3 ± 5.6, respectively (p = 0.010). The findings from the present pilot RCT highlighted that inhaler personalisation based on PIF among COPD patients was feasible and practical.

Exposure to respirable silica contributes to lower airway inflammation in asthmatic horses.

Respirable mineral particles can induce lower airway inflammation, but the role they play in asthma of horses is unknown. Respirable mineral particles, particularly respirable silica, are an overlooked determinant of chronic lung inflammation (asthma) in horses. Twenty-three horses from an equine hospital population: 11 moderately affected (MEA), 7 severely asthmatic (SEA), and 5 control horses free from respiratory clinical signs. Prospective observational study. The quantity and quality of mineral particles found in bronchoalveolar lavage fluid (BALF) were characterized, with particular attention to silica content. Polarized light microscopy performed on cytospin slides identified intracellular birefringent particles as silica. Spectrometry-based analysis performed on whole BALF determined total mineral and silica percentage and concentration. Group-related differences in BALF mineral and silica load were investigated as well as associations with BALF cytology. Intracellular birefringent particles were increased in SEA vs MEA (median [interquartile range, IQR]), 12 [7] vs 4 [5] particles/30 high power fields [hpf], respectively; P = .01) and vs controls (4 [2] particles/30 hpf; P = .02). Total mineral concentration in BALF was similar between the groups studied, whereas silica concentration and percentage were increased in SEA vs MEA (1758 [887] particles/mL and 20 [10]% vs 867 [662] particles/mL and 8 [6]%; P = .009 and P = .001) and control group (355 [330] particles/mL and 6 [3]%; P = .0003 and P = .002). Silica load in BALF was associated with BALF neutrophilia in MEA and SEA. Respirable silica is associated with neutrophilic lower airway inflammation in horses and might contribute to asthma development.

Numerical simulation of particles distribution of environmental tobacco smoke (ETS) and its concentration in a closed environment

Humans are frequently exposed to various chemical hazards, with smoking being a significant source of indoor air pollution. This pollution is particularly pronounced in environments such as smoking rooms, conference halls, cafes, and coffee houses. This study focuses on analyzing the concentration, distribution, and behavior of emitted particles from both mainstream and sidestream smoke in a controlled smoking room environment. A critical aspect of the research is the consideration of the thermal plume generated by the smoker's body, particularly around the breathing zone, which plays a crucial role in the dispersion and inhalation of pollutants. To conduct this analysis, a computational fluid dynamics approach was employed, incorporating a displacement ventilation (DV) system integrated with a detailed surface mesh model of a standing manikin. A Lagrangian approach was utilized to track the particle paths, considering factors such as particle size, density, and initial velocity. This approach was complemented by an Eulerian method to simulate the complex airflow patterns within the smoking room, accounting for turbulent flow and temperature variations. The integration of these methods provides a comprehensive understanding of both the macroscopic and microscopic behaviors of smoke particles. The motion equations governing the particles incorporated several forces, including inertial drag force, viscous drag force, buoyancy force, and gravitational force. Additionally, the study examined the interaction between thermal plumes and smoke particles, particularly how temperature gradients around the body affect particle dispersion and concentration. The study meticulously evaluated the distribution and volume average of respirable suspended particles (RSPs) and nicotine by analyzing a plane opposite to the breathing zone of both heated and unheated manikins. It was observed that the thermal plume generated by the temperature gradient around the body could significantly alter the flow field of both sidestream and mainstream smoke between puff periods. The simulation results demonstrated that the thermal plume increased the concentration of RSPs in the breathing zone, highlighting a critical exposure pathway for smokers and nonsmokers alike. A significant increase of approximately 70% in the nicotine concentration is due to the thermal plume. The concentration of nicotine peaks at approximately 0.003 mg/m3 by the third second in smoker#1's (6 smokers' position) breathing zone. Specific configurations of the DV system showed varying efficiencies in reducing pollutant concentrations, emphasizing the need for targeted ventilation strategies. In a chamber with six smokers, researchers found that the time required for suspended particles to reach a cleaning ratio, considering the dynamics of particle movement due to smoking activity, was approximately 184 s per puff.

Novel inhalable nano-based/microparticles for enhanced sustained pulmonary delivery of remdesivir - A patient malleable treatment for coronaviruses infection: In vitro aerosolization, cytotoxicity assays and antiviral activity studies

Remdesivir (RDV) is an antiviral used in potential treatment of SARS-COV-2 infection during the COVID-19 pandemic worldwide. However, it is still limited to IV administration for hospitalized patients. Therefore, we report herein successful development of RDV-loaded nanosuspensions (NS) using polycaprolactone and pluronic® F127, for the first time. The optimized RDV-NS was further loaded into inhalable nano-based/microparticles (OLN-microparticles) via co-spray drying with hyaluronic acid and mannitol. OLN-microparticles exhibited high yield value ∼80.56 %, with satisfactory entrapment efficiency and drug loading percent ∼97.27 ± 1.84 % and 3.92 ± 0.07 %, respectively. Carr's index was equal to 22.7 ± 11.67 % indicating good flowability properties. Scanning electron microscopic analysis showed spherical-shaped particles. Transmission electron microscope demonstrated grape-shaped clumps surface porosity. OLN-microparticles exhibited excellent aerodynamic features including; emitted fraction ∼97.46 ± 1.70 %, respirable particle fraction 53.77 ± 0.2 %, effective inhalation index 72.39 ± 1.40 %, and mass median aerodynamic diameter 2.25 ± 0.01 μm. Compared to plain RDV, OLN-microparticles showed significantly enhanced sustained release (p < 0.0001) with 1.5 and 1.9 fold increase at 24 and 48 h, respectively in Gamble's solution. OLN-microparticles also showed favorable cytotoxic profile with CC50 ∼ 252.0 μg/mL, inhibitory concentration (IC50) 13.08 μg/mL, and safety index (SI) 19.26 which is 1.3 fold higher compared to plain RDV. The Optimal release profile of OLN-microparticles enabled controlled and sustained release with enhanced cellular uptake. Hence, OLN-microparticles represented an efficient alternative form of dry powder for inhalation for deep and targeted pulmonary delivery of RDV, outweighing limitations accompanied with IV administration. It can provide self-administered and malleable access of treatment for SARS-COV-2 infected patients.

Sterile inflammation induced by respirable micro and nano polystyrene particles in the pathogenesis of pulmonary diseases.

Sterile inflammation is involved in the lung pathogenesis induced by respirable particles, including micro- and nanoplastics. Their increasing amounts in the ambient and in indoor air pose a risk to human health. In two human cell lines (A549 and THP-1) we assessed the proinflammatory behavior of polystyrene nanoplastics (nPS) and microplastics (mPS) (Ø 0.1 and 1μm). Reproducing environmental aging, in addition to virgin, the cells were exposed to oxidized nPS/mPS. To study the response of the monocytes to the inflammatory signal transmitted by the A549 through the release of soluble factors (e.g. alarmins and cytokines), THP-1 cells were also exposed to the supernatants of previously nPS/mPS-treated A549. After dynamic-light-scattering (DLS) analysis and protein measurements for the assessment of protein corona in nPS/mPS, real-time PCR and enzyme-linked-immunosorbent (ELISA) assays were performed in exposed cells. The pro-inflammatory effects of v- and ox-nPS/mPS were attested by the imbalance of the Bax/Bcl-2 ratio in A549, which was able to trigger the inflammatory cascade, inhibiting the immunologically silent apoptosis. The involvement of NFkB was confirmed by the overexpression of p65 after exposure to ox-nPS and v- and ox-mPS. The fast and higher levels of IL-1β, only in THP-1 cells, underlined the NLPR3 inflammasome activation.

Evaluation of environmental emissions from glo heated tobacco products and combustible Cigarettes

Compared to cigarette smoke, heated tobacco product (HTP) aerosol contains significantly fewer and lower levels of harmful and potentially harmful constituents (HPHCs). However, the impact on environmental air is relatively unexplored. Therefore, this study compared levels of secondhand aerosol (SHA) constituents in air following glo HTP use with secondhand smoke (SHS) constituents following cigarette smoking in an environmental test chamber (ETC). Extracted ETC air samples following product use sessions were analyzed for 27 SHS/SHA constituents, including HPHCs. The use of glo HTPs resulted in significantly lower SHA HPHC levels in the ETC air relative to SHS HPHC levels from cigarette smoking. Some aerosol constituents (benzene, CO, formaldehyde, nicotine, respirable suspended particles, toluene, ethylbenzene, fine particulate matter, m- and p-cresol, o-cresol, pyridine, styrene, and ultraviolet particulate matter) were either below the limit of detection in ETC air or at significantly low levels following glo HTP use relative to cigarette smoking. Mean concentrations of the assessed constituents were at least 90 % lower following use of glo HTPs compared to smoking combustible cigarettes. These results suggest that glo HTP use would not contribute significantly to indoor air contamination and would reduce non-user exposure to HPHCs and other harmful constituents relative to combustible cigarettes. Such reductions in non-user exposure should be considered when assessing the tobacco harm reduction potential of glo HTPs.

Steamed hay and alfalfa pellets for the management of severe equine asthma.

Steaming hay significantly reduces respirable particles and provides a palatable alternative to dry hay for horses with asthma, but there are few prospective studies demonstrating the clinical efficacy of steamed hay. To compare the efficacy of alfalfa pellets and steamed hay in improving lung function and inflammation of horses with severe asthma (SEA). Controlled crossover study. Ten horses with SEA were enrolled and nine completed the study. Horses were housed indoors and fed hay. Once in exacerbation, they were fed pellets and steamed hay for 4 weeks, in a crossover design. Weighted clinical scores and lung function were recorded weekly. Bronchoalveolar lavage fluid (BALF) cytology and mucus scores were recorded before and after each diet. Based on linear mixed model (LMM) analysis, weighted clinical scores significantly improved over time (p < 0.001, no diet effect or time-diet interactions). With pellets, weighted clinical scores decreased from (median (interquartile range)) 13 (5.5) to 2 (1.5), while with steamed hay, they decreased from 10 (9.5) to 6 (8.5). With pellets, lung resistance decreased significantly from a baseline of (mean (SD)) 2.62 (0.77) cmH2O/L/s to 1.17 (0.66), 0.79 (0.54), 0.70 (0.20), 0.62 (0.18) on Weeks 1-4, respectively (LMM with post hoc tests, p < 0.001). With steamed hay, the resistance decreased significantly from a baseline of 2.34 (0.93) cmH2O/L/s to 1.38 (0.49) and 1.51 (0.66) on Weeks 1 and 2, respectively (p < 0.03). Neutrophils BALF decreased significantly with both diets (pellets: 40.2 (24.4) to 20.1 (11.0) %; steamed hay 30.9 (20.2) to 25.7 (17.6) %; LMM, p = 0.006). A small number of horses in a research setting. Dust was not measured in the stalls. Clinical scores, lung function and BALF inflammation of horses with SEA improved with steamed hay and pellets, but the effect on lung function was more pronounced with pellets.

Pulmonary osteoclast-like cells in silica induced pulmonary fibrosis.

The pathophysiology of silicosis is poorly understood, limiting development of therapies for those who have been exposed to the respirable particle. We explored mechanisms of silica-induced pulmonary fibrosis in human lung samples collected from patients with occupational exposure to silica and in a longitudinal mouse model of silicosis using multiple modalities including whole-lung single-cell RNA sequencing and histological, biochemical, and physiologic assessments. In addition to pulmonary inflammation and fibrosis, intratracheal silica challenge induced osteoclast-like differentiation of alveolar macrophages and recruited monocytes, driven by induction of the osteoclastogenic cytokine, receptor activator of nuclear factor κΒ ligand (RANKL) in pulmonary lymphocytes, and alveolar type II cells. Anti-RANKL monoclonal antibody treatment suppressed silica-induced osteoclast-like differentiation in the lung and attenuated pulmonary fibrosis. We conclude that silica induces differentiation of pulmonary osteoclast-like cells leading to progressive lung injury, likely due to sustained elaboration of bone-resorbing proteases and hydrochloric acid. Interrupting osteoclast-like differentiation may therefore constitute a promising avenue for moderating lung damage in silicosis.

Longitudinal changes in cardiovascular disease–related proteins in welders

ObjectiveOccupational exposure to welding fumes is linked to a higher risk of cardiovascular disease; however, the threshold exposure level is unknown. Here, we aimed to identify changes in proteins associated with cardiovascular disease in relation to exposure to welding fumes.MethodsData were obtained from two timepoints six years apart for 338 non-smoking men (171 welders, 167 controls); of these, 174 (78 welders, 96 controls) had measurements available at both timepoints. Exposure was measured as personal respirable dust (adjusted for personal protective equipment), welding years, and cumulative exposure. Proximity extension assays were used to measure a panel of 92 proteins involved in cardiovascular processes in serum samples. Linear mixed models were used for longitudinal analysis. The biological functions and diseases related to the identified proteins were explored using the Ingenuity Pathway Analysis software.ResultsAt both timepoints, the median respirable dust exposure was 0.7 mg/m3 for the welders. Seven proteins were differentially abundant between the welders and controls and increased incrementally with respirable dust: FGF23, CEACAM8, CD40L, PGF, CXCL1, CD84, and HO1. CD84 was significant after adjusting for multiple comparisons. These proteins have been linked to disorders of blood pressure, damage related to clogged blood vessels, and chronic inflammatory disorders.ConclusionExposure to mild steel welding fumes below current occupational exposure limits for respirable particles and welding fumes in Europe and the US (1–5 mg/m3) was associated with changes in the abundance of proteins related to cardiovascular disease. Further research should evaluate the utility of these proteins as prospective biomarkers of occupational cardiovascular disease.

Respiratory Effects and Pulmonary Functions Related to Wood Dust Exposure among Workers in a Rubber Wood Factory

This study aimed to determine the effects of wood dust exposure on respiratory symptoms and pulmonary functions in wood dust factory workers and the association between wood dust exposure and pulmonary functions. This cross-sectional study comprised of one hundred workers who answered a self-reported questionnaire. Two factory areas, the production department and the back office, were explored using stationary air sampling. The wood dust concentration was collected using NIOSH Method 0600. Pulmonary function parameters were evaluated through spirometry. A descriptive statistics analysis was done for personal information. Binary logistic regression determined the association between wood dust exposure and respiratory symptoms. The prevalence of respiratory symptoms related to wood dust exposure at work was 49.00 percent. Three major symptoms in the exposed group includes chest pain, shortness of breath, and asthma. The average amount of PM10 in the saw mill area was significantly higher than in the back office (7.23 vs. 1.60 mg/m3). There was a significant difference in forced expiratory capacity between the reference and exposure groups (mean difference = -4.03, p-value = 0.011). The adjusted odd ratio showed that the high wood dust-exposed group had a lower runny nose and dry cough than the reference group. All workers need to consider using personal protective equipment with appropriate specifications in the sawmill area and also the other areas where wood dust levels are high. To control the concentration of respirable particles, resource and pathway control must be applied to reduce the concentration of respirable particles in the workplace.

How safe are 3D-printed skull models for neurosurgical simulation? Measurement of airborne particles and VOCs while burr hole drilling

PurposeThree-dimensional (3D)printed skulls for neurosurgical training are increasingly being used due to the widespread access to 3D printing technology, their low cost and accuracy, as well as limitations and ethical concerns associated with using human cadavers. However, little is known about the risks of airborne particles or volatile organic compounds (VOCs) released while drilling into 3D-printed plastic models. The aim of this study is to assess the level of exposure to airborne contaminants while burr hole drilling.Design/methodology/approach3D-printed skull samples were produced using three different materials (polyethylene terephthalate glycol [PETG], white resin and BoneSTN) across three different 3D print processes (fused filament fabrication, stereolithography [SLA] and material jetting). A neurosurgeon performed extended burr hole drilling for 10 min on each sample. Spot measurements of particulate matter (PM2.5 and PM10) were recorded, and air samples were analysed for approximately 90 VOCs.FindingsThe particulate matter for PETG was found to be below the threshold value for respirable particles. However, the particulate matter for white resin and BoneSTN was found to be above the threshold value at PM10, which could be harmful for long periods of exposure without personal protective equipment (PPE). The VOC measurements for all materials were found to be below safety thresholds, and therefore not harmful.Originality/valueTo the best of the authors’ knowledge, this is the first study to evaluate the safety of 3D-printed materials for burr hole surgical drilling. It recommends PETG as a safe material requiring minimal respiratory control measures, whereas resin-based materials will require safety controls to deal with airborne particles.

Effects of dust controls on respirable coal mine dust composition and particle sizes: case studies on auxiliary scrubbers and canopy air curtain

Control of dust in underground coal mines is critical for mitigating both safety and health hazards. For decades, the National Institute of Occupational Safety and Health (NIOSH) has led research to evaluate the effectiveness of various dust control technologies in coal mines. Recent studies have included the evaluation of auxiliary scrubbers to reduce respirable dust downstream of active mining and the use of canopy air curtains (CACs) to reduce respirable dust in key operator positions. While detailed dust characterization was not a focus of such studies, this is a growing area of interest. Using preserved filter samples from three previous NIOSH studies, the current work aims to explore the effect of two different scrubbers (one wet and one dry) and a roof bolter CAC on respirable dust composition and particle size distribution. For this, the preserved filter samples were analyzed by thermogravimetric analysis and/or scanning electron microscopy with energy dispersive X-ray. Results indicate that dust composition was not appreciably affected by either scrubber or the CAC. However, the wet scrubber and CAC appeared to decrease the overall particle size distribution. Such an effect of the dry scrubber was not consistently observed, but this is probably related to the particular sampling location downstream of the scrubber which allowed for significant mixing of the scrubber exhaust and other return air. Aside from the insights gained with respect to the three specific dust control case studies revisited here, this work demonstrates the value of preserved dust samples for follow-up investigation more broadly.

A Portable Infrared System for Identification of Particulate Matter.

Occupational exposure to airborne dust is responsible for numerous respiratory and cardiovascular diseases. Because of these hazards, air samples are regularly collected on filters and sent for laboratory analysis to ensure compliance with regulations. Unfortunately, this approach often takes weeks to provide a result, which makes it impossible to identify dust sources or protect workers in real time. To address these challenges, we developed a system that characterizes airborne dust by its spectro-chemical profile. In this device, a micro-cyclone concentrates particles from the air and introduces them into a hollow waveguide where an infrared signature is obtained. An algorithm is then used to quantitate the composition of respirable particles by incorporating the infrared features of the most relevant chemical groups and compensating for Mie scattering. With this approach, the system can successfully differentiate mixtures of inorganic materials associated with construction sites in near-real time. The use of a free-space optic assembly improves the light throughput significantly, which enables detection limits of approximately 10 µg/m3 with a 10 minute sampling time. While respirable crystalline silica was the focus of this work, it is hoped that the flexibility of the platform will enable different aerosols to be detected in other occupational settings.

Kinetics-based wetting properties of microdroplets impacting respirable coal dust particles

The removal of respirable coal dust particles has been the focus of domestic and foreign research, and the spray dust suppression technology has been adopted for the prevention and control process; it is based on the mechanism whereby liquid droplets impact dust particles. To further study the wetting properties of microdroplets impacting respirable coal dust particles based on kinetics, this study focused on the droplet morphology, and mathematical and physical models of a microdroplet impacting a respirable coal dust particle were established to explore the variation laws of the droplet spreading and wetting under central and non-central impacts, for which the CLSVOF numerical simulation approach was adopted. The results showed the occurrence of gas retention at the phase interface, which affected the droplet wetting characteristics on the coal dust surface, after the contact between the liquid and dust particles. The influence of the impact velocity, particle size ratio, contact angle, and offset distance on the droplet spreading behavior was investigated by comparative analysis of 12 working conditions with different parameters. The droplets can completely wrap the coal dust particles under only one working condition parameter (V = 5m/s,Φ = 2,θ = 90°,L = 0 μm). The microdroplets are extremely difficult to wet respirable coal dust particles and the spreading behavior of the final droplet could be divided into three states: static adsorption, complete encapsulation and permanent escape. Our results can help better understand the wetting relationship between microdroplets and respirable coal dust particles, serving as a basis for dust prevention and control.

Evaluating silicosis risk: Assessing dust constitution and influence of water as a primary prevention measure in cutting and polishing of silica agglomerates, granite and marble

An increasing number of silicosis cases have been reported related to the use of silica agglomerates. Many studies agree on the severity of this disease, which often presents with severe clinical forms in young workers and after a short latency period.Are there differences in the composition of dust generated by cutting and polishing with silica agglomerates versus granite and marble? Does the use of water injection reduce the risk associated with the use of these materials?We carried out a comparative observational-analytical study, measuring the concentration of dust generated during different machining operations on three different materials: granite, marble, and silica agglomerates. The effect of water injection on dust generation was evaluated.Personal sampling pumps were used, connected to a cyclone with polyvinyl chloride filters. The flow rate of the pumps was adjusted using a piston flowmeter. Measurements with a cascade impactor were made to assess the size distribution of respirable crystalline silica particles within the respirable fraction. In addition, environmental measurements with a spectrometer were made.10 tests were carried out on granite and silica agglomerates for each procedure. In the case of marble, with very low silica content, only 2 tests of each type were carried out. Duration of each measurement was between 6 and 25 min. Cleaning times were set for each of the operations.The amount of dust collected in the respirable fraction was 70.85, 32.50 and 35.78 mg/m3 for dry cutting; 6.50, 3.75 and 3.95 mg/m3 for wet cutting; and 21.35, 13.68 and 17.50 mg/m3 for dry polishing, for granite, marble, and silica agglomerates respectively.Dry procedures in marble, silica agglomerates and granite showed higher dust concentration of particles smaller than 0.5 μm. Silica agglomerates showed higher concentrations of respirable crystalline silica particles than granite and marble, mainly with dry procedures. The greater production of small particles in dry and wet procedures with silica agglomerates shows that water injection is an insufficient preventive measure.

Aerosol deposition and emission from a United States Pharmacopeia‐induction port when using a pressurized metered‐dose inhaler with and without a valved holding chamber

AbstractThe testing of pharmaceutical aerosols includes measuring the aerodynamic particle size distribution, which is usually performed on cascade impactors. In the next generation impactor (NGI), the aerosol dose is introduced through an induction port (IP), being separated into different aerodynamic diameter ranges by seven stages and a micro‐orifice collector. The IP plays an important role in estimating the oropharyngeal deposition fraction. While the IP retains mainly large particles, it also tends to retain particles in the respirable range. In this work, the deposition of particles in the IP of an NGI is studied, both experimentally and through computational fluid dynamic (CFD) simulations. Experimental tests are conducted both with the pressurized metered‐dose inhaler (pMDI) alone and in conjunction with a cylindrical valved holding chamber (VHC). For each case, the total mass deposition that occurs in the VHC, IP, and NGI stages is measured, as well as the mass median aerodynamic diameter of the aerosol leaving the IP. The CFD simulations show minimal variations in results regardless of the injection method due to the relatively low velocity and spray angle of the pMDI‐generated aerosol. If the flap‐valve is removed from the VHC, significant particle deposition occurs upstream or within the valve region, with downstream air recirculation contributing to small particle deposition. Based on the CFD results, a correlation is proposed to accurately predict the particle escape fraction of the IP and VHC, which allows estimation of the tannin distribution of particles collected in the NGI stages, especially those corresponding to the range of respirable particles.

Characterization of airborne dust emissions from three types of crushed multi-walled carbon nanotube-enhanced concretes

Dispersing Multi-Walled Carbon Nanotubes (MWCNTs) into concrete at low (<1 wt% in cement) concentrations may improve concrete performance and properties and provide enhanced functionalities. When MWCNT-enhanced concrete is fragmented during remodelling or demolition, the stiff, fibrous and carcinogenic MWCNTs will, however, also be part of the respirable particulate matter released in the process. Consequently, systematic aerosolizing of crushed MWCNT-enhanced concretes in a controlled environment and measuring the properties of this aerosol can give valuable insights into the characteristics of the emissions such as concentrations, size range and morphology. These properties impact to which extent the emissions can be inhaled as well as where they are expected to deposit in the lung, which is critical to assess whether these materials might constitute a future health risk for construction and demolition workers. In this work, the impact from MWCNTs on aerosol characteristics was assessed for samples of three concrete types with various amounts of MWCNT, using a novel methodology based on the continuous drop method. MWCNT-enhanced concretes were crushed, aerosolized and the emitted particles were characterized with online and offline techniques. For light-weight porous concrete, the addition of MWCNT significantly reduced the respirable mass fraction (RESP) and particle number concentrations (PNC) across all size ranges (7 nm – 20 μm), indicating that MWCNTs dampened the fragmentation process by possibly reinforcing the microstructure of brittle concrete. For normal concrete, the opposite could be seen, where MWCNTs resulted in drastic increases in RESP and PNC, suggesting that the MWCNTs may be acting as defects in the concrete matrix, thus enhancing the fragmentation process. For the high strength concrete, the fragmentation decreased at the lowest MWCNT concentration, but increased again for the highest MWCNT concentration. All tested concrete types emitted <100 nm particles, regardless of CNT content. SEM imaging displayed CNTs protruding from concrete fragments, but no free fibres were detected.

Stone mining work and dust pollution in Birbhum district, West Bengal, India.

Dust pollution is common in Indian roads and several industrial settings (including mines) that affects human health. Identification and characterization of the dust particles in the mining area is essential for knowing the properties of the dust that effectively causes ailments to humans, particularly among workers those who are working in unorganized industrial settings. The present study aimed to determine the level of dust pollution and to know the size and characterize the dust particles in the Pachami-Hatgacha stone mine areas of Birbhum district, West Bengal, India. Dust samples were collected and analysed for Dynamic Light Scattering (DLS) to determine the size and shape of the particles, Fourier Transform Infrared Spectroscopy (FT-IR) to determine the free silica content, and X-ray Florence (XRF) analysis for quantitative estimation of components in the sample. All the analyses were done following standard instrumentation and techniques. The size of the dust particles was much less (ranges 101-298nm) than the size of respirable particles (2500nm). Those were mostly generated as well as precipitated during peak working hours of the day. Presence of considerable amounts of silica was confirmed by the FT-IR (strong and broad band at 1000cm-1) and XRF analysis (76.85% SiO2). Exposure to these dust particles may cause severe health impairments. Therefore, interventions like wet drilling and blasting, sprinkling of water during peak working hours, and awareness of use of personal protective devices among workers are required to reduce the risk and hazards associated with dust pollution to the health of miners and inhabitants around the mines.