Air Dust Research Articles

Dust Concentration in Air during the MDF Boards and Polystyrene Milling Operations on CNC Milling Machine

During the material milling an amount of dust which can significantly influence surroundings is generated. Mainly workers are exposed to a dust pollution. The aim of this paper is to present results of a microclimatic research focused on the dust pollution in a workshop during the milling of MDF boards (Medium Density Fibreboards) and Polystyrene workpieces on CNC milling machine. The concentration of air dust was measured by the DustTRAK II Model 8530 aerosol monitor. Using the special impactors the PM1, PM2.5, PM4, PM10 size fractions were also measured. Obtained results of measurements and concentrations of different size of dust particles were analysed. The conclusion of the research is that it is necessary to watch the optimization of the milling process as well as secondary effects of the technological operations and the inner environment of workshops which can be contaminated by dust particles. A natural ventilation of the large space in which the CNC milling machine is installed is not sufficient. A recommendable solution for an improvement of the current situation is the installation of a local exhausting equipment.

Experimental investigation of limiting oxygen concentration of hybrid mixtures

An investigation into the limiting oxygen concentration (LOC) of fifteen combustible dusts and methane, ethanol and isopropanol hybrid mixtures in the standard 20 L explosion chamber was performed. Three ignition energies (10 J, 2 kJ and 10 kJ) were used. The results show that a 10 J electrical spark ignition leads to significantly higher limiting oxygen concentration values than either 2 kJ or 10 kJ pyrotechnic igniters. This could be due to the “overdriving” effect of the chemical igniters, which produce a hot flame that virtually covers the entire explosion chamber during combustion. With respect to hybrid mixture investigation, the 20 L sphere was modified to allow the input of methane gas and flammable solvents. The limiting oxygen concentrations of the hybrid mixtures were found to be considerably lower than those of dust air mixtures when the relatively weaker spark igniter was used. There was no significant change in limiting oxygen concentration when the higher energy chemical igniters were used.

Hygienic assessment of handicapped adolescents vocational training conditions: problems and optimization opportunities

In a number of occupations, there is a shortage of labor force that can be filled with economically active part of the population, including people with disabilities (handicapped, HC). Unfortunately, observance of hygienic requirements in the context of HP adolescents vocational training has not been studied sufficiently: most scholars have researched only the conditions of teaching healthy adolescents. This study aimed to examine the HC adolescents vocational training conditions and develop measures to improve their working conditions with pathologies factored in. We examined adaptation potential, anxiety level, mental efficiency, sick rate and personal well-being assessment in HC adolescents (n = 120) aged 16–18, not impaired intellectually, studying sewing equipment operation, shoe repairs in the boarding scool. In the context of the study, we applied Smirnov hygiene criteria, Giessen Symptom Questionnaire, Spielberger's Test Anxiety Questionnaire, Sivkov scale, correction tables, Baevsky adaptation index. For the purposes of statistical analysis, we used parametric (Student t-test) and non- parametric (Mann–Whitney) criteria. The Spearman's correlation coefficient helped determine interrelationship of the studied parameters. We identified the following key adverse hygienic factors that have a significant impact on the students' health: intense character of labor performed, insufficient artificial lighting, noise level above the norm, high content of organic solvents and dust in the workshop's air. The timetable of the boarding school was also found to be inefficient. The results of this study allowed developing and introducing a software program to automatically compile the school's timetable with the aim to improve psychosomatic health of the students and halve the number of health-related complaints.

Source identification of total petroleum hydrocarbons and polycyclic aromatic hydrocarbons in PM10 and street dust of a hot spot for petrochemical production: Asaluyeh County, Iran

Total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) are important pollutants that affect public health in urban areas, especially in developing and oil-rich countries such as Iran. This assesses the relationship between TPH and PAHs in street dust and suspended dust, and investigates toxicity level in the urban environment of the most important petrochemical center in Iran. For this purpose, 21 and 48 street dust samples were collected for TPH analysis and PAH analysis, respectively, in Asaluyeh County. Moreover, seven air dust samples were taken for PAH analysis. TPH concentrations ranged between 240 and 4400 mg kg−1, with a mean of 1371.43 mg kg−1. The maximum ∑PAH concentration (6016.3 mg kg−1) was detected in a petrochemical complex while the minimum ∑PAHs content (16.93 mg kg−1) was measured in an urban area. The mean concentrations of total PAHs in street dust particles were 491.35 mg kg−1 in summer and 304.04 mg kg−1 in winter. The results indicated that PAH concentration in summer was higher. PAH sources were identified using both PAHs ratios and robust statistical methods such as Generalized Estimating Equations (GEE), backward GEE, logistic regression, principal components analysis (PCA) in conjunction with multiple linear regression (MLR) and positive matrix factorization (PMF). The results showed that PAH species generally originate from pyrogenic sources and about 0.08% of TPH was typically PAHs. However, petrogenic sources of PAHs in the industrial areas were 11.2 times more abundant than in urban areas. Also, backward GEE model demonstrated that TPH is more influenced by HMW PAHs, particularly indene. Estimated incremental lifetime cancer risk (ILCR) was higher than 10-4, showing that Asaluyeh inhabitants (especially children and indoor workers) are probably exposed to cancer risk, particularly through dermal contact and dust ingestion.

Numerical Simulation of Particulate Matter 2.5 Distribution in a Roadway

Large amounts of dust particles pose serious hazards to the health and safety of China’s coal miners during roadway blasting processes. It is known that among these dust particles, Particulate Matter 2.5 (PM2.5) does the greatest amount of harm. In order to study the distributions of the PM2.5 in roadway blasting processes, a mathematical model of the gas-solid two-phase flow was established in this study, which was based on a Direct Simulation Monte Carlo Method (DSMC). Then, a multiphase flow program was developed. This study’s results indicated that following the blasting processes, fine dust particles gradually floated up and were suspended for long durations in the underground roadway space. The medium-sized dust particles slowly sink to the ground and were eventually expelled before settling to the floor of the roadway. The coarse particles were rapidly settled to the roadway floor. It was determined that the PM2.5 particles in the front end of the dust group could not be quickly diluted, and the concentrations were high until it is expelled from the roadway, whereas the PM2.5 dust particles in the back end of the underground roadway were found to be gradually diluted. Eventually, the PM2.5 concentrations exhibited an alternating thin to dense phase distribution. When compared with the Particulate Matter 5 (PM5), it was found that the PM2.5 was more difficult to discharge, and easily formed serious PM2.5 dust air pollution. This study’s results were determined to be conductive to the future control of PM2.5 in the underground roadway blasting processes.

Investigation of Thermal Explosion Formation in Heterogeneous Systems

The analysis and necessity for studying of burning processes of systems formed by coal dust and methane for the purpose of development the effective activities on the enterprises of coal branch were shown. The results demonstrate the role of nonflammable components in the combustion processes of air suspension in heterogeneous systems. Also the dependence of the critical conditions creation for flame propagation in air suspension of sucrose from the average particle diameter at different temperatures of the ignition source is presented. The necessity of taking into account the experimental and methodological experience of other industries for the study of air suspension sensitivity to the initiating influence of the ignition source is explored. The requirements to the installation and methodology for studying the sensitivity of coal dust air suspension as one of the main factors preventing explosions of heterogeneous systems in the coal industry are formulated.

Dust Air Pollution in Delhi: Creation of Artificial Huge Lakes for A Holistic Solution

Dust Air Pollution in Delhi: Creation of Artificial Huge Lakes for A Holistic Solution

Nano-porous aluminum oxide membrane as filtration interface for optical gas sensor packaging

Packaging and filtration is critical for photonic gas sensors as they are vulnerable to contaminations of dust and moisture in the ambient air. In this work, we present a prototype of packaging using nano-porous anodized aluminum oxide (AAO) as filtration interface for an optical CO2 gas sensor based on evanescent fields of silicon waveguides. An acrylate-type package housing for the AAO membrane was designed, manufactured and assembled via implementing additive manufacturing technologies including 3D-printing and inkjet printing. Simulation and experimental results for the corresponding package shows a minimal influence of response time while providing a significant filtration performance.

The effect of air dust pollution on semen quality and sperm parameters among infertile men in west of Iran

Background: Pollutants during haze and Asian dust storms are transported out of the Asian continent, affecting the regional climate and the hydrological and biogeochemical cycles. Nonetheless, no specific studies evaluated the dust particles influence on semen quality in a specific geographical area.Objective: In this article, we investigated the effect of dust particles on semen quality and sperm parameters among infertile men.Methods: A descriptive-analytic study was conducted among 850 infertile men between 2011 and 2015 years. Semen quality was assessed according to the WHO 2010 guidelines, including sperm concentration, progressive motility, and morphology. Four-year average dust particle concentrations were estimated at each participant’s address using the Air Pollution Monitoring Station affiliated with the Department of Environment of Kermanshah city were gathered.Results: Dust particle levels were highest in the summer months, in Kermanshah province. Our results show that, dust pollution was found to be significantly negatively correlated with sperm morphology and sperm concentration before and after lab-processing, but sperm progressive motility is low sensitive to dust particles.Conclusions: Our findings showed that exposures to dust particle may influence sperm quantity in infertile men, consistent with the knowledge that sperm morphology and concentration are the most sensitive parameters of dust pollution.

On the effect of initial pressure on the minimum explosive concentration of dust in air

Standard explosion tests were performed in the 20 l sphere to measure the minimum explosion concentration (MEC) of nicotinic acid in air at different initial pressures. CFD simulations were also run in order to gain insight into the experimental results particularly in terms of effects of initial pressure on turbulent flow field, and dust dispersion and feeding efficiency.According to the literature results, it has been found that MEC increases with increasing initial pressure. This trend has been attributed to the decrease of the burning velocity with pressure.It has been shown, via CFD simulations, that the actual dust concentration in the whole vessel and at the center of the vessel, where ignition is provided, is much lower than the nominal dust concentration. Thus, the MEC values measured in the sphere on the basis of the nominal dust concentration are misleading. We computed a scale factor to correct the “nominal” MEC, MECNominal, to the “actual” MEC, MECActual. In particular, we may suggest that, when measuring the MEC in the standard 20 l apparatus, MECActual may be obtained by multiplying MECNominal by the ratio, γ, between the dust concentration in the center of the vessel (@ t = 60 ms) and the nominal dust concentration: MECActual = γ MECNominal. MECActual is much less sensitive to variations in initial pressure than MECNominal.

Inhalation of House Dust and Ozone Alters Systemic Levels of Endothelial Progenitor Cells, Oxidative Stress, and Inflammation in Elderly Subjects.

Ambient air pollution including ozone and especially particulate matter represents important causes of cardiovascular disease. However, there is limited knowledge on indoor air dust with respect to this risk and the potential interactions between dust and ozone. Here, we exposed 23 healthy elderly subjects for 5.5 h, to either clean air, house dust at 275 µg/m3 (diameter < 2.5 µm), ozone at 100 ppb or combined house dust and ozone in a double-blinded randomized cross-over study. The combined house dust and ozone exposure was associated with a 48% (95% CI 24%-65%) decrease as compared with the clean air exposure, in CD34+KDR+ late endothelial progenitor cells (EPCs) per leukocyte in the blood shortly after exposure, whereas none of the single exposures resulted in a significant effect. The combined exposure also increased reactive oxygen species production capacity in granulocytes and monocytes as well as an up-regulation of interleukin-8 mRNA levels in leukocytes. Ozone alone reduced the gene expression of tumor necrosis factor and C-C motif chemokine ligand 2, while dust alone showed no effects. The combined exposure to house dust and ozone also reduced levels of oxidized purines in DNA consistent with concomitant up-regulation of mRNA of the repair enzyme 8-oxoguanine DNA glycosylase. The reduction in late EPCs can be an indicator of cardiovascular risk caused by the combination of pulmonary oxidative stress induced by ozone and the inflammatory potential of the house dust. These data were corroborated with in vitro findings from exposed human macrophages and endothelial cells.

Factors determining the exposure of dairy farmers to thoracic organic dust

Bronchial respiratory diseases are more common in dairy farmers than in the general population, perhaps because the repeated inhalation of organic dust contributes to the development of these disorders. However, the factors determining the exposure of farmers to particles that can enter the lower bronchial tract and interact with it, i.e. the thoracic fraction of the inhalable dust, remain to be identified.We therefore measured the exposure of dairy farmers to thoracic organic dust and identified the farm features and tasks that increased exposure. We measured thoracic particles (n = 110) and farm characteristics and occupational tasks in 29 Brittany dairy farms. The mean (GM) (geometric standard deviation, GSD) concentration of thoracic dust in air inhaled by farmers was 0.24 mg/m3 (2.8) and the concentrations of endotoxins, Gram-positive bacteria and fungi in the thoracic fraction were 128 EU/m3 (4.0), 960 CFU/m3 (6.3) and 690 CFU/m3 (5.4), respectively. Model-based estimates of the association between exposure, farm features and tasks indicated that manual grain and feed handling and mechanical bedding spreading significantly increased exposure to thoracic dust, endotoxins, bacteria and fungi. Exposure to bacteria and fungi was reduced by cowsheds divided into cubicles, whereas using automatic muck scrappers in alleyway and automatic milking tended to increase exposure to bacteria and endotoxins. Finally, exposure to endotoxin and fungi were reduced by warmer farm buildings and well-ventilated buildings having walls with large openings.In conclusions, major occupational tasks and specific farm features determine the exposure of Breton dairy farmers to thoracic organic dust.

Numerical Simulation of Spark Ignition of a Coal Dust–Air Mixture

This paper describes the development of a physico-mathematical model of spark ignition of a coal dust–air mixture, which is based on a two-phase two-speed model of reacting gas-dispersion medium. There are the results of numerical solution on the problem of spark ignition of a coal dust–air mixture with allowance for its movement caused by gas expansion during heating. The relationships between the minimal energy of spark ignition of a coal dust–air mixture and the mass concentration and particle size of coal dust are obtained. The particle size increases along with the minimal energy of spark ignition. There is mass concentration of coal dust particles with which the energy of spark ignition is minimal. The comparison of the results of calculations of the minimal energy of spark ignition of coal dust with known experimental data yields their satisfactory agreement.

Aerodynamic Resistance of a Ball-Tube Mill During Transport of a Polydisperse Coal Gas Suspension

Analysis of experimental data on aerodynamic resistance of a ball-tube mill is given. It is shown that this resistance has two components brought about by the pressure losses resulting from the injection of dust particles into the main flow after coal grinding and from the transport of homogeneous gas suspension flow. A dimensionless equation has been obtained for the dependence of the pressure loss in flow of a homogeneous dust–air mixture on Reynolds number. Functional dependences of the mean-square velocity of the floating of coal particles and of their average diameter on the polydispersity parameters of coal dust have been found. An empirical dependence of pressure loss due to the injection of a polydisperse coal gas suspension into the main flow on the average velocity of floating of coal particles, their average size, and on the size of the mill has been obtained.

In vitro exposure of nasal epithelial cells to atmospheric dust.

Dust storms are common phenomena in many parts of the world, and significantly increase the level of atmospheric particulate matter (PM). The soil-derived dust is a mixture of organic and inorganic particles and even remnants of pesticides from agricultural areas nearby. The risk of human exposure to atmospheric dust is well documented, but very little is known on the impact of inhaled PM on the biological lining of the nasal cavity, which is the natural filter between the external environment and the respiratory tract. We developed a new system and methodology for in vitro exposure of cultured nasal epithelial cells (NEC) to atmospheric soil-dust pollutants under realistic and controlled laboratory simulations that mimic nasal breathing. We exposed cultured NEC to clean and dust-polluted airflows that mimic physiological conditions. The results revealed that the secretion of mucin and IL-8 from the NEC exposed to clean and dust-polluted airflows was less than the secretion at static conditions under clean air. The secretion of IL-8 from NEC exposed to dust-polluted air was larger than that of clean air, but not larger than in the static case. The experiments with dust air pollution that also contained agricultural pesticides did not reveal differences in the secretion of mucin and IL-8 as compared to the same pollution without pesticides.

Modelling of Dust Dispersion of Emissions from Expanded Clay Manufacturing in the Atmosphere

The manufacturing of expanded clay represents a certain hazard to the environment and human health. The emissions contain a significant amount of fine dust, and the enterprises are located in close proximity to residential areas. Fine dust particles can stay in the air for a long time, they are transported over long distances thereby increasing the contaminated zone. The OND-86 method (the Industry Regulatory Document) is used to calculate dust dispersion in the atmosphere, which does not take into account a series of factors that determine the dispersion parameters, for example, air humidity. The authors have obtained one-parameter regression equations between the concentration of expanded clay dust in atmospheric air and the influencing factors: air temperature, relative air humidity, distance from the source, wind speed. A strong correlation dependence between the concentration of expanded clay dust and the relative air humidity has been established. An adequate multiple correlation equation that establishes a relationship between the dust concentration and the factors listed has been obtained. The given equation was used in practice when performing dispersion calculations, including the forecasting ones. The authors give the forecast of pollution with expanded clay dust for 2018.

Fabrication of Simple Indoor Air Haze Purifier using Domestic Discarded Substances and Its Haze Removal Performance

Based on the concept of circular economy, discarded plastic bottles stuffed with discarded cotton, clothing and sofa cushion were used as pre-filter to remove big particles (dust and coal dust) in air and 4 L tap water in discarded plastic bottle was worked as an absorbing medium to dissolve the water soluble ions in air (SO42-, NO3-, NH4+, Cl- and Ca2+). Moreover, the internet control design was used in this homemade indoor air haze purifier to achieve the performance of remote control and intelligent management. The experimental results showed that this indoor air haze purifier can effectively reduce the level of indoor air haze and the air quality after 20 minutes treatment is higher than that of two commercial well-known air haze purifier

A state of the art regarding urban air quality prediction models

Urban pollution represents an increasing risk to residents of urban regions, particularly in large, over-industrialized cities knowing that the traffic is responsible for more than 25% of air gaseous pollutants and dust particles. Air quality modelling plays an important role in addressing air pollution control and management approaches by providing guidelines for better and more efficient air quality forecasting, along with smart monitoring sensor networks. The advances in technology regarding simulations, forecasting and monitoring are part of the new smart cities which offers a healthy environment for their occupants.

Analysis of granulometric dust accumulating in supply and exhaust ventilation filters

The research aim was to analyse and compare the composition of granulometric dust which accumulates in air filters located in central air handling units supporting the production rooms and at the same time the degree and a kind of contamination fraction of atmospheric air in a part of Wrocław situated outside the city centre. Samples were taken in different seasons of the year, such as March and October. The size of pollution particles extracted from ventilation filters was measured with the use of ANALYSETTE 22MicroTec plus laser particle sizer produced by FRITSCH. The results of measurements were generated with MaScontrol software for particle size analysis. In computing research results, the Fraunhofer diffraction theory was used. The comparison of the examined air particles’ size in an air supply canal allowed to determine the outside air dust size in Szczepin district on Długa street in Wrocław. Moreover, the influence of the year season on the size of contaminants accumulating in filters was also determined in the course of research works.

An experimental study on effect of dust on power loss in solar photovoltaic module

In the present study, a detailed investigation on air dust particles effect on photovoltaic (PV) model performance has been carried out. The scanning electron microscope analysis of the collected dust samples was being carried out, and the obtained images were being analyzed in order to observe the character and topography of the dust sample particles. The data for dust samples of different weights with change in power loss in a PV module at three solar irradiations levels of 650, 750 and 850 W/m2 have been collected. In present study, the effect of environmental dust particles on power loss in PV module has been evaluated by measuring the electrical performance index such as voltage, current and power. The minimum power value of 3.88 W has been observed during the accumulation of rice husk on PV module.