Dust Loading Research Articles

Physical, mechanical and sliding wear behaviour of epoxy composites filled with micro-sized marble dust composites

The main purpose of this paper is to establish the utilization of waste material i.e. marble dust for the preparation of polymeric composites. Here, epoxy/marble stone dust composites are prepared for different content of marble stone dust using the hand lay-up method and their physical, mechanical and sliding wear properties are evaluated. In the present investigation, it is observed that the addition of micro-sized marble stone dust increases the density as well as the void content of the epoxy composites. The addition of filler in epoxy results in low absorption of water i.e. 1.15 % for maximum filler loading of 40 wt% and immersed in water for a duration of 168 h. The tensile strength and flexural strength show decreasing trends with filler loading, whereas, the tensile modulus, flexural modulus, compressive strength and hardness are increasing with marble stone dust loading. The tensile strength and flexural strength of the composite marginally decrease to 28.5 MPa and 37.2 MPa respectively for a marble dust loading of 40 wt%. The maximum compressive strength and hardness obtained in the work are 94 MPa and 86.2 Shore-D number respectively which is an appreciable increment over the properties of neat epoxy. Taguchi’s experimental design was used to obtain the optimal parameter setting to minimize a specific wear rate. From the analysis, it was found that the content of marble dust is the most noteworthy factor in minimizing the material loss of the composite body.

Impacts of the Aerosol Representation in WRF-Solar Clear-Sky Irradiance Forecasts over CONUS

Abstract Aerosol optical depth (AOD) is a primary source of solar irradiance forecast error in clear-sky conditions. Improving the accuracy of AOD in NWP models like WRF will thus reduce error in both direct normal irradiance (DNI) and global horizontal irradiance (GHI), which should improve solar power forecast errors, at least in cloud-free conditions. In this study clear-sky GHI and DNI was analyzed from four configurations of the WRF-Solar model with different aerosol representations: 1) the default Tegen climatology, 2) imposing AOD forecasts from the GEOS-5 model, 3) imposing AOD forecasts from the Copernicus Atmosphere Monitoring Service (CAMS) model, and 4) the Thompson–Eidhammer aerosol-aware water/ice-friendly aerosol climatology. More than 8 months of these 15-min output forecasts are compared with high-quality irradiance observations at NOAA SURFRAD and Solar Radiation (SOLRAD) stations located across CONUS. In general, WRF-Solar with GEOS-5 AOD had the lowest errors in clear-sky DNI, while WRF-Solar with CAMS AOD had the highest errors, higher even than the two aerosol climatologies, which is consistent with validation of the four AOD550 datasets against AERONET stations. For clear-sky GHI, the statistics differed little between the four models, as expected because of the lesser sensitivity of GHI to aerosol loading. Hourly average clear-sky DNI and GHI were also analyzed, and they were additionally compared with CAMS model output directly. CAMS irradiance performed competitively with the best WRF-Solar configuration (with GEOS-5 AOD). The markedly different performance of CAMS versus WRF-Solar with CAMS AOD indicates that CAMS is apparently less sensitive to AOD550 than WRF-Solar is. Significance Statement Particles in the atmosphere called aerosols, which can include dust, smoke, sea salt, sulfates, black carbon, and organic carbon, absorb and scatter incoming sunlight. Improving the representation of aerosols in numerical weather prediction models reduces forecast errors in solar irradiance at ground level, particularly direct normal irradiance, during cloud-free conditions. This in turn should result in improved accuracy of solar power forecasts, especially for concentrated solar power (CSP) plants. CSP plants tend to be built in more arid, less cloudy regions that are also prone to dust loading, so accurate aerosol forecasts are particularly relevant. Comparing four representations of aerosols in the WRF-Solar model over eight months of forecasts across the United States reveals substantial differences in clear-sky irradiance forecast skill.

Sensitivity of the Tropical Dust Cycle to Glacial Abrupt Climate Changes

AbstractDuring abrupt climate changes of the last glacial period paleorecords show large amplitude changes in the dust cycle. We use Earth System model simulations to evaluate processes operating across these events. Idealized Heinrich stadial‐like simulations show a southwards migration of tropical rainfall that dries the Sahel and reduces wet deposition causing a widespread enhancement of tropical dust loading. However, several discrepancies with marine core dust deposition reconstructions are evident. Simulations with a more limited freshwater forcing (0.4 Sv instead of 1.0 Sv) and weaker cooling over the North Atlantic (less than 3°C) show a switch in sign of the stadial dust deposition anomaly in several regions, improving agreement with paleorecords. The simulated dust cycle therefore displays in places a non‐linear response to abrupt change. The global‐mean stadial dust radiative forcing in the more realistic simulations is around −0.2 to −0.6 W m−2 and so could represent an amplifying feedback during these events.

Mineral dust aerosols over the Himalayas from polarization-resolved satellite lidar observations

Mineral dust aerosols over the Himalayas are assessed using polarization-resolved observations of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite over 11 years (2006–2018). The extinction coefficient due to dust aerosols is retrieved using observations of the depolarization ratio which gives the relative contribution of dust aerosols in the scattering volume. Dust extinction coefficients show significant regional and seasonal variation over the Himalayas. High dust loading is observed during the pre-monsoon season (March–May) whereas dust loading is low during the summer monsoon season (June–September). This is due to the reduced dust transport associated with the weak westerlies that prevailed over the Himalayas. Regionally, the mid-Himalayas is characterized by the highest dust extinction coefficient with a 10-fold increase as the season changes from winter (December–February) to pre-monsoon (March–May). Polluted dust (dust combined with anthropogenic aerosols) contributes to 64–74% of total aerosols over the Himalayas. Dry deposition causes a substantial amount of dust aerosols (1–31 mg m−2 day−1) to be deposited over the Himalayas, reducing the albedo by 0.3% on fresh snow and up to 2.7% on aged snow, causing a radiative forcing of 0.38–23.7 Wm-2 at the top of the atmosphere. The Himalayan cryosphere may therefore experience large warming leading to snow melting and enhanced reduction in snow cover.

Features of early diagnosis of the upper airways pathology affected by dust load

Features of early diagnosis of the upper airways pathology affected by dust load

Analysis of Air Supply Air Flow Rate Decrease by Accelerated Dust Load Experiments on Heat-Recovery Ventilator Air Filter

Purpose: Recently, owing to the high concentration of fine dust, air filters have become essential in heat-recovery ventilators. In Korea, air filter performance is evaluated by the standard, “KS B 6141 Air Filter Units for Ventilation.” However, filter lifetime has not been examined. In this study, an accelerated test method for air filters was developed. In addition, the change in the supply air flow rate was analyzed under filter conditions. Method: The filter accelerated test conditions were identified, and the annual average concentration of fine dust in the atmosphere was determined. A vertical wind tunnel was built to evaluate the air filter lifetime. The ISO A2 dust was dosed to an air filter. In addition, the supply air flow rates were measured for the three products that the accelerated air filter used. Result: Under the lab test conditions, the supply air flow rate changed with the filter usage time and the air resistance. In the experiments, only ISO A2 dust was used. Subsequently, the effects of various particles were tested on the development of the acceleration test method for filters.

Dust radiation effect on the weather and dust transport over the Taklimakan Desert, China

The regional and longer-duration dust weather in the Taklimakan Desert (TD) is mostly caused by the east-pathway dust events, which bring large amounts of dust aerosol to impact the local weather and air quality, but the dust-induced radiation feedback on meteorological processes and the dust cycle in TD is still unclear. Both dust absorption and scattering of shortwave (SW) and longwave (LW) radiation are important for dust radiation feedback (DRF), while most numerical simulations neglect the dust LW scattering effect. In this paper, we modify WRF-Chem v3.8.1 (Weather Research and Forecasting model coupled with chemistry) to include the full dust radiation effect in an only-dust simulation. Three east-pathway TD dust events were simulated by this modified WRF-Chem. For each dust event, four sensitive experiments were conducted: with SW + LW DRF, with only SW DRF, with only LW DRF, and without DRF. The modified WRF-Chem can reproduce the dust evolution and reasonably simulate the DRF. DRF enhances the mean 2-m air temperature (T2m) field by ∼1 °C in the TD and lowers the daily T2m range in the southern TD by 1.9–4.3 °C. The positive feedback of mean T2m owns mostly to two equally important contributors, i.e., the dust LW radiation impact and the synergistic impact between dust SW and LW radiation quantified by the factor separation technique. For these dust events, DRF enhances both dust loading (10–20%) and dust deposition in most TD areas, but with different impacts on the dust emission in the hinter (increasing) and the southern edge (decreasing) of the TD area. With a dynamic lift caused by mountain forcing and the DRF, the dust plume could be lifted higher in the southern TD.

Effect of dust formation on the fate of indoor phthalates: Model analysis

Phthalate esters (PAEs) are widely used in indoor environments and exist in the air, on airborne particles, in settled dust, and on material surfaces. To explore the effect of dust formation on the fate of indoor phthalates, a long-term mass transfer model of PAEs was proposed in this study, accounting for the change in dust loading caused by particle dynamics in the dust formation process as well as the porous properties of the dust layer. In addition, the model was evaluated by comparing it with experimental data from previous studies. By analyzing the simulation results, the following conclusions were drawn: (1) in the process of dust formation, phthalates in the dust boundary layer on the source surface reach the steady-state faster and the steady-state dust-phase concentration (value of 35,843 μg/g) is 10 times higher compared to a non-source surface (value of 3202 μg/g); (2) the particle size has an effect on the concentration of phthalates in the dust. Specifically, the dust-phase concentration of di(2-ethylhexyl) phthalate increases with the increase in particle size on both source and non-source surfaces; (3) gas and particle-phase transfers have different influences on the dust-phase concentration of phthalates on different surfaces; and (4) cleaning activities can effectively reduce the indoor phthalate concentration.

Artisanal stone-mining impacts on leaf microstructures and biochemical parameters of some plants at Eziani, Nsukka, Nigeria

Plants are determinant of air quality and are useful in mitigating air pollution and biomonitoring of the pollution stresses. Present study assessed the effect of stone-mining dust accumulation on foliar parameters and air pollution tolerance index (APTI) of five plants (Annona senegalensis, Bridelia ferruginea, Ficus capensis, Nauclea latifolia and Protea madiensis) commonly growing around an artisanal stone-mining site at Eziani Nsukka and Botanic Garden of the University of Nigeria, Nsukka, the control. Dust load was estimated gravimetrically. The foliar analysis carried out on the epidermises was obtained by clearing method and studied under microscope and all photomicrographs were taken with Moticam Camera 2.0 attached to the microscope. Biochemical parameters and APTI were determine following standard methods. Dust accumulated on polluted plant leaves was high and resulted in distortion and deformation of the epidermal and guard cells. The cells appeared stretched and broken compared to the control plants. Quantitative stomatal indices such as length, width, size and density were also significantly affected by dust pollution. Polluted plants showed increase in ascorbic acid, reduction in pH values, relative water content and total chlorophyll content, and produced low tolerance index than the controls. Highest and lowest APTI were found in A. senegalensis and B. ferruginea. At polluted site, A. senegalensis had APTI (17.14 ± 0.24) and B. ferruginea had (11.38 ± 0.07) which differed significantly from the APTI of A. senegalensis (18.92 ± 0.24) and B. ferruginea (13.49 ±0.28) at the control site. A. senegalensis was the most tolerant to air pollution while other plants were intermediate tolerant plants. The abnormalities in artisanal stone-mining plants may be due to prolonged exposure to dust. However, ability of the plants to tolerate air pollution makes them potential good environmental cleaners and as such, are recommended as choice plants around stone-mining and dust-polluted sites for safer environments and better health of both miners and the inhabitants.

Effects of various humid environments on the filtration and dust cleaning performance of filter media

The filtration technology is gaining popularity in underground projects which are characterized by a poor working environment. However, the influence of various humid environments on the filtration performance of filter media (FM) has not been clarified yet. This study is the influence of humid environments on the performances of common mechanical filter media (MFM) and polytetrafluoroethylene coated filter media (CFM). First, the methods to control the dust moisture content, relative humidity and spray rate were determined. Then, the influences of dust loading on the pressure drop, filtration velocity and dust cleaning performance in various humid environments were explored. The results indicate that the maximum pressure drops of MFM and CFM both grow first and then decline with the increase in dust moisture content. The different is that the maximum pressure drops of MFM and CFM both decrease with the rise of relative humidity. In addition, the maximum pressure drops of MFM and CFM both decline first and then rise with the acceleration of the spray. Under the same humid environment, MFM correspond to a larger maximum value and a greater variation of pressure drop than CFM. When the dust moisture content, relative humidity or spray rate increases, the residual pressure drops of both FM grow after dust cleaning, but the latter corresponds to a smaller growth.

Case Study of the Saharan Dust Effects on PM10 and PM2.5 Concentrations in Budapest in March 2022

The Earth's climatic system is greatly dependent on atmospheric mineral dust. Dust particles are regarded as one of the less well-known contributors to recent climatic changes, much like other aerosol constituents. Fifty to seventy percent of the world's budget for mineral dust comes from the Sahara Desert areas. These sources can produce dust-loaded air masses that can travel great distances and affect many parts of the world including Europe, the Middle East, North and South America. In March 2022 Europe faced two Saharan Dust storms (14-19 and 28-31), that affected many countries including Hungary. We used registered measurements of PM10 and PM2.5 concentrations from urban background air quality station in Budapest and MONARCH model to assess the effects of the two Saharan Dust storms on Budapest. As measured by daily average concentrations, PM10 and PM2.5 concentrations rose by 12 µg/m3 and 10 µg/m3 respectively during the first Saharan Dust event (SDE1), and by 14 µg/m3 and 5 µg/m3 during the Second Saharan Dust event (SDE2). While the effects of both SDEs on PM10 were nearly identical, SDE1 had a greater impact on PM2.5 concentrations than SDE2. Moreover, the dust load arriving to Budapest as estimated by the MONARCH model was higher in the SDE1 (1.26 g/m3), and that was associated with high values of dust surface concentration and Dust optical depth (243.1 µg/m3 and 0.71).

Depositional conditions of the Upper Younger Loess during the Last Glacial Maximum in central and eastern Europe

This paper is a summary of the results of research on the accumulation conditions of the Upper Younger Loess (LMg) in Poland and Bug loess (bg) in Ukraine from the maximum stage (MIS 2) of the Vistulian (Weichselian) Glaciation in central and eastern Europe. These studies included an analysis of the morphological (topographic) situation of the loess cover, its grain size and heavy mineral composition, the preserved structures of loess sedimentation as well as mollusc and pollen analyses of this loess. They revealed that the accumulation of Upper Younger Loess (UYL) might have been more dependent on the prevailing moisture conditions than previously thought. These conditions could have been caused by cold air masses from an ice sheet and warm air masses from the Mediterranean Sea and Atlantic coming together in the Carpathians and the Holy Cross Mountains and favouring the formation of dust storms and precipitation. In this process, a loading of loess dust (formed from local rocks weathering in periglacial conditions) by atmospheric moisture particles was especially significant. The moist substrate not only favoured the periodic development of vegetation and molluscs but also enabled the interception of dust and the accumulation of an increasingly thick loess cover. Westerly and south-westerly winds predominated in the UYL as indicated by the topographic position of loess patches and the mineral composition of the studied loess. Periodically an increased air circulation from the east and northeast occurred.

Atypically Intense and Delayed Response of the Martian Ionosphere to the Regional Dust Storm of 2016: A Study Using MAVEN Observations and Models

AbstractDuring Mars dust storms, atmospheric heating and expansion moves the ionospheric peak upward. Typically, peak altitude increases by no more than 10 km, and this increase occurs simultaneously with the expansion of the dust storm. However, Felici et al. (2020), https://doi.org/10.1029/2019JA027083, using the Mars Atmosphere Volatile EvolutioN (MAVEN) Radio Occultation Science Experiment (ROSE), reported an unusually large increase of ∼20 km at southern latitudes in early October 2016 during a modest dust storm. Here, we investigate why the ionospheric peak altitude increased so much in these observations. We extend the time series of ionospheric peak altitude values beyond the limited extent of the ROSE observations by applying a one‐dimensional photochemical model, in which neutral atmospheric conditions are based on in situ MAVEN Neutral Gas Ion Mass Spectrometer observations at similar latitudes and solar zenith angles to those observed by ROSE. We find that the ionospheric peak altitude was highest throughout October 2016 yet both the local and global atmospheric dust loading were greatest 1 month earlier. We hypothesize that (a) a portion of the unusually large 20 km enhancement in peak altitude and (b) the unusual delay between the greatest dust loading and the highest peak altitude were both associated with the occurrence of perihelion, which maximizes solar heating of the atmosphere, in late October 2016.

Investigation of Two Severe Shamal Dust Storms and the Highest Dust Frequencies in the South and Southwest of Iran

Dust storms create some of the most critical air quality problems in the world; the Middle East, located in the dust belt, suffers substantially from dust storms. Iran, as a country in the Middle East, is affected by dust storms from multiple internal and external sources that mostly originate from deserts in Iraq and Syria (especially the Mesopotamia region). To determine the highest dust loadings in the south and west of Iran, dust frequencies were investigated in the eight most polluted stations in the west, southwest, and southern Iran for a period of 21 years from 2000 to 2021. During the study’s duration, the dust frequency was much higher from 2008 to 2012, which coincided with severe droughts reported in Iraq and Syria; from which, we investigated two severe dust storms (as well as the dust sources and weather condition effects) that took place on 15–17 September 2008 and 1–3 June 2012; we used secondary data from ground measurement stations, and satellite and modeling products. In both cases, horizontal visibility was reduced to less than 1 km at most weather stations in Iran. The measured PM10 in the first case reached 834 μg m−3 at Ilam station in west Iran and the Iran–Iraq borders while the measured PM10 in the second case reached 4947 μg m−3 at Bushehr station in the northern shore of the Persian Gulf. The MODIS true color images and MODIS AOD detected the dust mass over Iraq, southern Iran, and Saudi Arabia in both cases; the AOD value reached 4 in the first case and 1.8 in the second case over the Persian Gulf. During these two severe dust storms, low-level jets were observed at 930 hPa atmospheric levels in north Iraq (2008 case) and south Iraq (2012 case). The output of the NAPPS model and CALIPSO satellite images show that the dust rose to higher than 5 km in these dust storm cases, confirming the influence of Shamal wind on the dust storm occurrences.

Influence of pleated geometry on the pressure drop of filters during dust loading process: experimental and modelling study

In this study, a pressure drop model was developed through numerical simulation and experimentation for optimizing the design of the pleated structure of the filter media to extend the service life of the filter and reduce the ventilation energy consumption. The effect of the Stokes number on the dust deposition on the pleated filter media was revealed through numerical simulation. On this basis, a pressure drop model during dust loading was developed. The model suggests that under the same mass of dust deposition per unit area (W), the greater the pleat ratio (α), the greater the dust cake thickness and the effective filtration velocity in the effective filtration area. In addition, for V-shaped and U-shaped filters, the relative mean deviations between experimental and modeling total pressure drops are 3.68% and 4.82%, respectively. In other words, the proposed model accurately predicts pressure drop during dust loading. Furthermore, under the same α and W, the total pressure drop of the U-shaped filter is lower than that of the V-shaped filter, demonstrating the superior filtration performance of the U-shaped filter.

The simulation of mineral dust in the United Kingdom Earth System Model UKESM1

Abstract. Mineral dust plays an important role in Earth system models and is linked to many components, including atmospheric wind speed, precipitation and radiation, surface vegetation cover and soil properties and oceanic biogeochemical systems. In this paper, the dust scheme in the first configuration of the United Kingdom Earth System Model UKESM1 is described, and simulations of dust and its radiative effects are presented and compared with results from the parallel coupled atmosphere–ocean general circulation model (GCM) HadGEM3-GC3.1. Not only changes in the driving model fields but also changes in the dust size distribution are shown to lead to considerable differences to the present-day dust simulations and to projected future changes. UKESM1 simulations produce a present-day, top-of-the-atmosphere (ToA) dust direct radiative effect (DRE – defined as the change in downward net flux directly due to the presence of dust) of 0.086 W m−2 from a dust load of 19.5 Tg. Under climate change pathways these values decrease considerably. In the 2081–2100 mean of the Shared Socioeconomic Pathway SSP5–8.45 ToA DRE reaches 0.048 W m−2 from a load of 15.1 Tg. In contrast, in HadGEM3-GC3.1 the present-day values of −0.296 W m−2 and 15.0 Tg are almost unchanged at −0.289 W m−2 and 14.5 Tg in the 2081–2100 mean. The primary mechanism causing the differences in future dust projections is shown to be the vegetation response, which dominates over the direct effects of warming in our models. Though there are considerable uncertainties associated with any such estimates, the results presented demonstrate both the importance of the size distribution for dust modelling and also the necessity of including Earth system processes such as interactive vegetation in dust simulations for climate change studies.

Spatio-temporal changes of spring-summer dust AOD over the Eastern Mediterranean and the Middle East: Reversal of dust trends and associated meteorological effects

High dust concentrations in the Eastern Mediterranean - Middle East (EMME) region have serious effects on air quality, human health and climate. This study used long-term aerosol datasets during the main dusty season (April–July: AMJJ) over the EMME from 2000 to 2020, based on Moderate-Resolution Imaging Spectroradiometer (MODIS)/Terra-C6.1, Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2), and Copernicus Atmosphere Monitoring Service Reanalysis (CAMSRA) retrievals and analyzed the spatio-temporal variations and trends of dust, as well as the influencing factors. The dust aerosol optical depth (DAOD) experienced a significant upward trend during 2000–2010, followed by a significant decrease during 2010–2017. After 2017 and till 2020, the DAOD presented rather a stable trend. Aerosol Robotic Network (AERONET) data in the EMME region display trends compatible to those of both MERRA-2 and CAMSRA DAOD. The DAOD trends were linked to changes in regional meteorological parameters in the EMME. A significant downward trend in AMJJ sea-level pressure (SLP) during the early period (2000−2010) induced hot and dry winds from desert regions towards the EMME, which reduced relative humidity (RH) and raised temperature, thus favored soil drying and dust outbreaks through enhancing evaporation. In contrast, a significant increase in winter SLP during the late period (2010–2017), accompanying an increase in North Atlantic Oscillation index, induced cold, wet winds from northwest regions, which increased RH and lowered temperature, thus reducing dust loading in EMME. Positive anomalies in winter soil moisture persisted in the following AMJJ, and consequently suppressed dust activity. DAOD variability over the dust-prone regions was linked to various meteorological parameters via a multiple linear regression (MLR) model. The results show that climatic variability strongly affects the dust trends and contribute to better understanding of meteorological – dust dynamics in the EMME region.

Spatial variability and trend analysis of dust aerosols loading over Indian sub-continent using MERRA 2 & CALIPSO data

ABSTRACT This paper summarizes the spatial-temporal analysis of aerosol dust loading and aerosol dust extinction over the Indian subcontinent for identifying trends and patterns for a period of 40 years from 1980 to 2019. These analyses are based on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data using Modern-Era Retrospective Analysis for Research and Applications, Version 2. The high-resolution data of CALIPSO indicate a high concentration of dust column mass density over the northwestern part of India. It increases from central India to Rajasthan and Jammu & Kashmir regions. Mean dust aerosol optical depth also suggests an increase in the dust loading over northwestern part of the country.

Seasonal and daily occurrence of microplastic pollution in urban road dust

In recent years, microplastic pollution and its potential ecological risks have attracted a lot of attention. The pollution level of microplastics (MPs) in urban road dust has already been demonstrated. However, the occurrence mechanism of MPs in road dust still remains to be understood, especially for the seasonal and daily occurrences. In this study, seasonal and daily pollution characteristics of MPs in the road dust of Ma'anshan city, China were investigated. On average, the abundances of MPs were 7.48 ± 10.56 n·m−2 in spring, 5.17 ± 5.18 n·m−2 in summer, 4.32 ± 5.54 n·m−2 in autumn and 8.58 ± 7.07 n·m−2 in winter. There was no significant difference in the abundances of MPs among various seasons (F = 1.448, p = 0.236). As the main polymers, the proportions of PP (Polypropylene), PE (Polyethylene) and PET (Polyethylene Terephthalate) were found to be 71.51%, 22.16% and 1.04% in spring, 48.63%, 16.13% and 24.56% in summer, 59.58%, 23.66% and 7.80% in autumn, and 59.53%, 23.47% and 8.33% in winter, respectively, wherein the abundances of PE and PET varied with seasons (p < 0.05). More specifically, based upon numbers, MPs were dominated by fragments (50.27%) in shape, <1000 μm (65.02%) in size and black (36.22%) in color. Moreover, the abundances of MPs had a significant correlation with the dust load (p < 0.05). The diversity integrated indices of MPs were 0.42 ± 0.14 in spring, 0.51 ± 0.10 in summer, 0.38 ± 0.17 in autumn, and 0.40 ± 0.13 in winter, indicating a seasonal difference (F = 3.46, p = 0.02). This suggests that even though the abundance of MPs did not vary with season, their polymers and apparent morphology did change. Particularly, there was no obvious accumulation of MPs with the increase in the antecedent dry days on urban road due to the frequent road-cleaning practice.

A risk of pulmonary diseases in miners while using dust respirators

Purpose. To determine magnitudes of the occupational risks of respiratory disease (pneumoconiosis) occurrence in miners while using filter respirators on the basis of an exposure dust dose with the consideration of work experience. Methodology. To assess occupational risks, a new approach proposed by the Research Institute of Complex Hygiene and Occupational Diseases is used. The approach is based on determining an exposure dose of a hazardous substance entering the workers lungs during their professional contact with it taking into account the volume of pulmonary ventilation, the number of shifts, and work experience. Findings. Use of dust respirators reduces the risk of occupational respiratory diseases but does not eliminate it completely. It has been established that with more than three-year work experience and coal dust concentrations of more than 50 mg/m3, use of dust filter respirators does not ensure a minimal degree of the occupational disease risks. At the same time, it has been identified that if work experience is less than 3 years with the use of filter respirators, the risk of occupational diseases will be minimal. It has been proved that the risk assessment should involve using the minimal value of a protection factor of a respirator, which is fixed in the production environment. It has been shown that working within the areas with dust concentrations higher than 100 mg/m3 is dangerous for miners; over time, with the accumulation of sufficient dust in the lungs it will lead to the development of silicosis. Originality. It consists in scientific substantiation of the magnitude of occupational risk of respiratory diseases in miners, taking into account a real protection factor of respirators, which is determined at the workplace based on the calculation of an exposure dose and time of professional contact with hazardous substances. Practical value. The experience of safe operation in mine workings with and without using filter respirators has been substantiated, basing on a safe value of coal dust concentration, at which a low level of occupational risk of respiratory diseases is recorded. Recommendations for determining the dust load taking into account a protection factor of respirators at the workplace have been developed.