Average PM10 Mass Concentration Research Articles

Pollution characteristics, source apportionment, and health risk assessment of PM10 and PM2.5 in rooftop and kerbside environment of Lanzhou, NW China.

To investigate air pollution in the kerbside environment and its associated human health risks, a study was conducted in Lanzhou during December 2018, as well as in April, June, and September 2019. The research aimed to characterize the composition of PM10 and PM2.5, including elements, ions, and carbonaceous components, at both rooftop and kerbside locations. Additionally, source apportionment and health risk assessment were conducted. The results showed that the average mass concentrations of PM10 on the rooftop were 176.01 ± 83.23μg/m3, and for PM2.5, it was 94.07 ± 64.89μg/m3. The PM10 and PM2.5 levels at the kerbside are 2.21 times and 1.79 times, respectively, greater than those on the rooftop. Moreover, the concentrations of elements, ions, and carbonaceous components in kerbside PM were higher than those at the rooftop location. Chemical mass closure analysis identified various sources, including organic matter, mineral dust, secondary ions, other ions, elements, and other components. In comparison to rooftop particulate matter (PM), mineral dust makes a more substantial contribution to kerbside PM. Secondary ions show an opposite trend, making a greater contribution to rooftop PM. The contribution of organic components within PM of the same particle size remains relatively consistent. The outcome of the health risk assessment indicates that Co, Cd, and As in PM within the kerbside and rooftop environments do not pose a notable carcinogenic risk. However, Al and Mn do present specific non-carcinogenic risks, particularly in the kerbside environment. Furthermore, children experience elevated non-carcinogenic risk compared to adults. These findings can serve as a scientific foundation for formulating policies within the local health department.

In-depth characterization of particulate matter in a highly polluted urban environment at the foothills of Himalaya-Karakorum Region.

In recent years, the rising levels of atmospheric particulate matter (PM) have an impact on the earth's system, leading to undesirable consequences on various aspects like human health, visibility, and climate. The present work is carried out over an insufficiently studied but polluted urban area of Peshawar, which lies at the foothills of the famous Himalaya and Karakorum area, Northern Pakistan. The particulate matter with an aerodynamic diameter of less than 10µm, i.e., PM10 are collected and analyzed for mineralogical, morphological, and chemical properties. Diverse techniques were used to examine the PM10 samples, for instance, Fourier transform infrared spectroscopy, x-ray diffraction, and scanning electron microscopy along with energy-dispersive x-ray spectroscopy, proton-induced x-ray emission, and an OC/EC carbon analyzer. The 24h average PM10 mass concentration along with standard deviation was investigated to be 586.83 ± 217.70µg/m3, which was around 13 times greater than the permissible limit of the world health organization (45µg/m3) and 4 times the Pakistan national environmental quality standards for ambient PM10 (150µg/m3). Minerals such as crystalline silicate, carbonate, asbestiform minerals, sulfate, and clay minerals were found using FTIR and XRD investigations. Microscopic examination revealed particles of various shapes, including angular, flaky, rod-like, crystalline, irregular, rounded, porous, chain, spherical, and agglomeration structures. This proved that the particles had geogenic, anthropogenic, and biological origins. The average value of organic carbon, elemental carbon, and total carbon is found to be 91.56 ± 43.17, 6.72 ± 1.99, and 102.41 ± 44.90µg/m3, respectively. Water-soluble ions K+ and OC show a substantial association (R = 0.71). Prominent sources identified using Principle component analysis (PCA) are anthropogenic, crustal, industrial, and electronic combustion. This research paper identified the potential sources of PM10, which are vital for preparing an air quality management plan in the urban environment of Peshawar.

The composition of the bacterial communities collected from the PM10 samples inside the Seoul subway and railway station

Health implications of indoor air quality (IAQ) have drawn more attention since the COVID epidemic. There are many different kinds of studies done on how IAQ affects people’s well-being. There hasn’t been much research that looks at the microbiological composition of the aerosol in subway transit systems. In this work, for the first time, we examined the aerosol bacterial abundance, diversity, and composition in the microbiome of the Seoul subway and train stations using DNA isolated from the PM10 samples from each station (three subway and two KTX stations). The average PM10 mass concentration collected on the respective platform was 41.862 µg/m3, with the highest average value of 45.95 µg/m3 and the lowest of 39.25 µg/m3. The bacterial microbiomes mainly constituted bacterial species of soil and environmental origin (e.g., Acinetobacter, Brevundimonas, Lysinibacillus, Clostridiodes) with fewer from human sources (Flaviflexus, Staphylococcus). This study highlights the relationship between microbiome diversity and PM10 mass concentration contributed by outdoor air and commuters in South Korea’s subway and train stations. This study gives insights into the microbiome diversity, the source, and the susceptibility of public transports in disease spreading.

Physicochemical characteristics of atmospheric particles in south western (Pune) region of India: Elemental size distribution, source analysis and risk assessment

Chemical characteristics of size-resolved particulate matter (PM) and bound elemental species were investigated under an intensive measurement campaign during winter of 2021 in urban dwelling of south western (Pune) region of India. During the study period, average mass concentrations of PM10, PM4, PM2.5 and PM1 were 182.4 ± 48.7 μgm−3, 76.2 ± 26.2 μgm−3, 63.5 ± 22.4 μgm−3, 17.7 ± 6.9 μgm−3 respectively. Diurnal variability indicated significant high concentration during night and early morning hours attributed to the high volume of heavy-duty vehicles. Bimodal distributions of PM mass concentrations in coarse fraction (Mass Median Aerodynamic Diameter (MMAD) ± Geometric Standard Deviation (GSD) = 4.32 ± 1.27) was noted while accumulation of elements was found higher in fine(0.43–2.1 μm) > coarse(2.1–5.8 μm) > large mode(5.8–10 μm) particles. As per size distribution characteristics, Mn, Pb, Cu, Sn, Zn, Mo were concentrated in coarse mode; As, Cr, Fe, Ni was concentrated in both large and coarse mode while Al, Si depicted multimodal distribution across coarse and fine range. High MMAD (≥1.8) and GSD (>1.2) of all elements pointed towards significance of coarse particles in this study region. Ni and Cr (VI) via inhalation exposure pathway pose highest hazard quotient (HQ) and excess lifetime cancer risk (ELCR) respectively within respirable size range(2.1–3.3 μm) while children were subject to potential health risk than adults mainly through ingestion mode of exposure. Principal Component Analysis (PCA) suggested crustal origin, resuspended road dust along with vehicular traffic and industrial emissions as major sources.

PM10 Element Distribution and Environmental-Sanitary Risk Analysis in Two Italian Industrial Cities

In this work, an evaluation of the air of two Italian industrial cities, Turin and Biella, has been performed to identify the main sources affecting its quality and to evaluate its evolution along 15 years. These two cities are placed at the border of the Po valley, one of the most polluted areas of Europe, and the automotive and textile industries have been their main economic sectors. The elemental analysis of the PM10 collected there in 2007 has been performed by ICP-MS and ICP-AES. The results identify the urban activities and the soil/road dust resuspension as the main sources of metals. Biella was overall less polluted in PM10 than Turin, probably because of its smaller size, its smaller traffic volume, and the lower number of industries. However, the limit value imposed by the European legislation for daily average PM10 mass concentration (50 μg m−3) was frequently exceeded in the collected samples: 22% and 50%, respectively for Biella and Turin. The concentration of specific toxic metals regulated by Italian legislation was never higher than the limit value for Cd (4 ng m−3) and Pb (0.5 μg m−3), whereas it was exceeded for Ni (20 ng m−3) in 22% of the samples from Turin and only in the 5% of those from Biella. In the same way, the risk analysis, performed using the target hazard quotient (THQ), calculated for children and adult populations, did not reveal warning values. Only for Cd in children were concerning values found (median THQ = 4.9). Element concentrations showed a seasonal trend, with higher values in November and December due to a combination of stable atmospheric conditions and strengthening of anthropic sources (e.g., combustion for heat generation). Finally, data concerning the amount of Cd, Ni, and Pb in the atmosphere provided by the regional agency for environmental protection (ARPA Piedmont) have been used to follow the evolution of these elements from 2007 to 2021 in the two cities. The data reveal a significant reduction of the concentrations of all considered metals in all the sites (higher than 50%), however maintaining the seasonal variability observed in PM10 samples of 2007, with higher concentrations during the cold months and lower concentrations during the summer.

Exploring the Mass Concentration of Particulate Matter and Its Relationship with Meteorological Parameters in the Hindu-Kush Range

Particulate matter (PM) is among the deadliest air pollutants due to its negative health impacts and environmental harm. This study reports on monthly and seasonal concentrations of PM10, PM2.5, and PM1, along with their ratios. Twelve-day samples were collected once a month in Mingora city (Swat, Pakistan) from January to December 2019 using a low volume sampler. Maximum average mass concentrations of PM10, PM2.5, and PM1 were recorded in December having values of 78, 56, and 32 μg m−3, respectively. Minimum average values for PM10 (44 μg m−3) and PM2.5 (25.1 μg m−3) were recorded in April, while the lowest PM1 (11 μg m−3) was recorded in August. In comparison to other months, the maximum average mass concentrations were 1.77 times (PM10), 2.23 times (PM2.5), and 2.9 times (PM1) higher in December. During the winter season, average mass concentrations remained high. Substantial correlation coefficients of 0.92, 0.79, and 0.75 were recorded between PM10 and PM2.5, PM2.5 and PM1, and PM2.5 and PM1, respectively. The overall average ratios PM2.5: PM10, PM1: PM2.5, and PM1: PM10 were 68.3, 52.6, and 35.4%, respectively. A moderate negative correlation of PM10, PM2.5, and PM1 with wind speed (−0.34, −0.39, and −0.41), a strong negative correlation with temperature (−0.69, −0.71, and −0.74) and rainfall (−0.63, −0.61, and −0.59), and a weak relationship with relative humidity (−0.32, −0.1, and −0.02) were recorded.

Elucidating the Chemical Compositions and Source Apportionment of Multi-Size Atmospheric Particulate (PM10, PM2.5 and PM1) in 2019–2020 Winter in Xinxiang, North China

The pollution characteristics of multi-size atmospheric particulates in Xinxiang, which was one of the most polluted cities across China, are still unclear even through air quality in Xinxiang has been improved in recent years. PM10, PM2.5, and PM1 samples were synchronously collected from 21 December 2019 to 17 January 2020 to explore pollution levels and reveal sources of PM in Xinxiang. The average mass concentrations of PM10, PM2.5, and PM1 were as high as 155.53 μg m−3, 120.07 μg m−3, and 85.64 μg m−3 during the observation period, respectively. Almost all of the chemical compositions in PM10, PM2.5 and PM1 increased continuously and obviously with the aggravation of the pollution level. Compared with the clean period, the enhancement of sulfate (23–27%) in PM was obvious higher than nitrate (19–22%) during the pollution period, which demonstrated that sulfate was the main contributor to the high concentration of PM in this study. Similar source distributions for PM10, PM2.5, and PM1 were also found, including traffic source, combustion source, secondary aerosols, industrial source, and fugitive dust, by using the positive matrix factorization (PMF) model. Furthermore, the contributions of the combustion source and secondary aerosol were found to be higher in smaller particles (PM2.5 and PM1), while the contribution of fugitive dust was higher in PM10. Moreover, dust and sand were entrained by air masses from the northwest that increased the contribution of dust in PM at the observation site. The potential source contribution function (PSCF) analysis illustrated that regional emission sources in northern and eastern Xinxiang might be important potential contributors to PM pollution in Xinxiang.

Variation in Coarse Particulate Matter (PM10) and Its Characterization at Multiple Locations in the Semiarid Region

Introduction: The elemental composition and morphological study of particulate matter are very important to understand the nature of particles influencing the environment, climate, soil, and health.Methods: The PM10 samples were collected during the winter season (2018) in Nowshera city, KPK, Pakistan, in three locations, namely, urban, industrial, and suburban. Scanning electron microscopy (SEM) and electron-dispersive X-ray (EDX) spectroscopy were used to examine the PM samples for morphological examination and elemental composition.Results: The average mass concentrations of particulate matter (PM10) at the urban, industrial, and suburban locations were 238.5, 505.1, and 255.0 μg m−3, respectively. The average PM10 mass concentration was higher than the WHO and National Ambient Air Quality Standards (NAAQS). The results of EDX showed that samples contained variable amounts of thirteen elements, such as oxygen, carbon, silicon, magnesium, sodium, calcium, iron, aluminum, potassium, sulfur, titanium, gold, and chlorine. The probable sources of PM were biogenic like plant debris, pollen, and diatoms; geogenic like road dust and resuspended soil dust; and anthropogenic like carbonaceous particles and fly ash, as confirmed by SEM–EDX. The carbonaceous species, that is, OC and EC, had average values of 55.8 ± 13.1 and 4.6 ± 0.6, 5.2 ± 3.2, and 36.4 ± 10.4, 40.0 ± 2.6 and, 6.3 ± 0.2 in industrial, urban, and suburban locations, respectively. Similarly, OC/EC had average values of 12.0 ± 1.2, 8.0 ± 3.0, and 6.3 ± 0.2 in industrial, urban, and suburban locations, respectively. Highly significant correlations among water-soluble ions (K+), OC, and EC were found in each location.Conclusions: The examined PM10 mass concentration in Nowshera city was above the thresholds of National Ambient Air Quality Standards (NAAQS) set by the U.S. Environmental Protection Agency (EPA). In addition, the concentration of pollutants was the highest at the industrial site compared to the other sites. The HYSPLIT model showed that the air mass originated from local sources like cement industries, brick kiln industries, and others.

Bioaerosols in the Athens Metro: Metagenetic insights into the PM10 microbiome in a naturally ventilated subway station

To date, few studies have examined the aerosol microbial content in Metro transportation systems. Here we characterised the aerosol microbial abundance, diversity and composition in the Athens underground railway system. PM10 filter samples were collected from the naturally ventilated Athens Metro Line 3 station “Nomismatokopio”. Quantitative PCR of the 16S rRNA gene and high throughput amplicon sequencing of the 16S rRNA gene and internal transcribed spacer (ITS) region was performed on DNA extracted from PM10 samples. Results showed that, despite the bacterial abundance (mean = 2.82 × 105 16S rRNA genes/m3 of air) being, on average, higher during day-time and weekdays, compared to night-time and weekends, respectively, the differences were not statistically significant. The average PM10 mass concentration on the platform was 107 μg/m3. However, there was no significant correlation between 16S rRNA gene abundance and overall PM10 levels. The Athens Metro air microbiome was mostly dominated by bacterial and fungal taxa of environmental origin (e.g. Paracoccus, Sphingomonas, Cladosporium, Mycosphaerella, Antrodia) with a lower contribution of human commensal bacteria (e.g. Corynebacterium, Staphylococcus). This study highlights the importance of both outdoor air and commuters as sources in shaping aerosol microbial communities. To our knowledge, this is the first study to characterise the mycobiome diversity in the air of a Metro environment based on amplicon sequencing of the ITS region. In conclusion, this study presents the first microbial characterisation of PM10 in the Athens Metro, contributing to the growing body of microbiome exploration within urban transit networks. Moreover, this study shows the vulnerability of public transport to airborne disease transmission.

The influence of a viaduct on PM dispersion in a typical street: Field experiment and numerical simulations

To investigate the effects of a viaduct on particle diffusion below the viaduct, field measurements for particulate matter (PM) concentration along roadsides with and without viaducts were conducted in this study. Air flow and particle (PM2.5) distribution around a viaduct were simulated by Computational Fluid Dynamic (CFD) equipped with the Discrete Phase Model in a Lagrange coordinate system. Experimental results of this case study indicate that the average mass concentrations of PM10 (156.7 μg m−3), PM2.5 (77.3 μg m−3) and PM1 (56.5 μg m−3) on an elevated highway exceeded those on the ground–level expressway by 15%, 10% and 12%, respectively. Simulation found that two main vortices as well as two or three secondary vortices are generated in the canyon when both a viaduct and a barrier are added, while there was only one main vortex in the street canyon without a viaduct. A viaduct causes the particulate matter to be distributed unevenly, and the concentration on the leeward side near the ground is the highest. The vortex center is elevated as the value of ΔT (ground–level air temperature) increases, but the concentrations are basically maintained. We concluded that a viaduct increases the concentration of particulate matter in the street canyons and greatly affects the airflow field. Both ΔT and a sound barrier on a viaduct reduce the PM concentrations, but the effects are limited.

Distributions of mass concentrations and metal compositions of fine and ultrafine particles in lower socio-economic areas in a metropolitan city of Korea

TPS 642: Environmental justice and impacts, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background: Socio-economic status (SES) would be a major risk factor of pollutant exposure. This study was conducted to reveal different concentrations and patterns of fine and ultrafine particle exposure in lower SES areas. Methods: Study was performed from August 2015 to July 2016 in three lower SES areas, A (heavily industrialized area), B (port area), C (beach area), in a metropolitan city (Busan) Korea. Mini Volume Air Sampler with 47 mm QMA Filter of flow rate of 5.0 L/min were used to sample PM10 and PM2.5 for 24 hours in three roof tops in centers of those areas during a weekday and weekend of each month. ICP/OES and ICP/MS were used to check 8 elements and 14 metals. Results: Average mass concentrations of PM10 and PM2.5 of area A were highest of 53.1 μg/m3 and 36.4 μg/m3, which excesed Korean annual limit (PM10 50 μg/m3, PM2.5 25 μg/m3). Those of area C were lowest (PM10 (37.9 μg/m3), PM2.5 (22.1 μg/m3)). Mass concentrations of PM10 and PM2.5 of spring exceeded 1.16 times and 1.26 times of Korean limits. Artificial origin elements (Cd, Cr, Cu, Mn, Ni, Pb, Zn) of PM10 and PM2.5 were highest in area A. Annual average contribution rate of soil was 13.9%. Regional and seasonal contribution rate of soil of PM2.5 were different with PM10. Elements with over 100 of enrichment factor were S, Cd, Pb, Mo, As, Zn, Cu, Cr, V, Ni in order (higher PM2.5 than PM10). Elements such as As, Cd, Na, S, V were higher in area B. Conclusions: Fine and ultrafine particle concentrations in three different area showed different patterns according to exposure source and season. This might be contributed by atmospheric difference such as wind speed and direction, which causes different effects of artificial origin from neighbor or remote area.

Pollution Characteristics of Ambient Fine Particulate Matters at Mt. Halla-1100 and Gosan Sites in Jeju Island

Ambient fine particulate matters of PM10 and PM2.5 were collected at the Mt. Halla-1100 site (a site at an altitude of 1100 meters on Mt. Halla) and the Gosan site, which comprise a typical mountainous site and coastal background site, respectively, on Jeju Island. The major water-soluble ionic species of these sites were analyzed. The average mass concentrations of PM10 and PM2.5 at the Mt. Halla-1100 site were 0.59 times lower and 0.78 times lower, respectively, than those at the Gosan site. The composition ratios of the major secondary air pollutants (nss-SO42-, NO3-, and NH4+) of PM10 and PM2.5 were 86.2% and 93.2%, respectively, at the Mt. Halla-1100 site, while those at the Gosan site were 67.7% and 87.2%, respectively. These results show the comparatively larger contributions at the Mt. Halla-1100 site. The principal component analysis reveals that the main affecting factors for the ionic compositions of PM10 and PM2.5 particles at both sites are the anthropogenic emission sources, especially the comparative influence of organic acids at the Mt. Halla-1100 site, and the marine sources at the Gosan site. Based on the neutralization factors, the fine particulate matters were acidified mainly by sulfuric and nitric acids, and the neutralization was relatively caused by calcium carbonate in PM10 particles and ammonia in PM2.5 particles. The clustered back trajectory analyses indicated that the major ionic concentrations of PM10 and PM2.5 comparatively increased when the airflow moved from continental China and the Korean Peninsula. The polluting influence from China was apparent in the upper planetary boundary layer (PBL) compared with that at ground level. Key Words: PM10, PM2.5, Mt. Halla-1100 site, Gosan site, Planetary Boundary Layer (PBL)

Brominated flame retardants in a computer technical service: Indoor air gas phase, submicron (PM1) and coarse (PM10) particles, associated inhalation exposure, and settled dust

Brominated flame retardants (BFRs) are found in multi-media indoors, therefore, may pose serious risks to human health. This study investigated the occurrence of BFRs in particulate matter (PM1 and PM10) and gas phase by active and passive sampling, and settled dust to estimate potential exposure in a computer technical service. Polybrominated diphenyl ethers (PBDEs) and their alternatives (novel BFRs, NBFRs) were studied. PM and gas phase were collected on glass fiber filters and polyurethane foam plugs, respectively, and analyzed with a GC/MS after extraction, clean-up, and concentration. Inhalation exposure of the staff was estimated based on the measured concentrations using Monte Carlo simulation. BDE-209 was the dominating PBDE congener in all media while bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate and 1,2-bis(2,4,6-tribromophenoxy)ethane were those of NBFRs. Submicron particulate matter (PM1) BFR levels constituted about one half of the PM10-associated concentrations, while average PM10 mass concentration (69.9 μg m−3) was nine times that of PM1 (7.73 μg m−3). Calculated log10 dust-gas and PM-gas partitioning coefficients ranged from −5.03 to −2.10, −2.21 to −0.55, and −2.26 to −1.04 for settled dust, PM10, and PM1, respectively. The indoor/outdoor concentration ratios were >1 for all compounds indicating the strength of indoor sources in the service. The estimated potential inhalation exposures, for future chronic-toxic and carcinogenic risk assessments, indicated that the levels of gas-phase and PM1-associated exposures were similar at approximately one half of PM10-associated levels. Results of this study indicate that the occurrence of BFRs in all studied media should be taken into consideration for occupational health mitigation efforts.

Indoor-outdoor association of particulate matter and bounded elemental composition within coarse, quasi-accumulation and quasi-ultrafine ranges in residential areas of northern India

Attempts have been made to comprehend size distribution pattern of Particulate Matter (PM) and associated elemental concentration within coarse (2.5–10μm), quasi-accumulation (q-Acc) (0.25–2.5μm) and quasi-ultrafine (q-UF) (<0.25μm) ranges at indoors and outdoors of residential homes of Agra. Overall, the average mass concentrations of PM10 and PM2.5 in indoors were found to be 263.24±59.24 and 212.01±38.06μgm−3 while in outdoors the concentrations accounted to 194.28±15.25 and 152.88±16.31μgm−3 respectively; exceeding WHO standards. In view of geographical variation, significantly higher (t=2.461; P=0.044) PM mass was found in outdoor samples of roadside location when compared to homes located far away from busy traffic; whereas indoor concentration exhibited non-significant relationship (t=1.887; P=0.095) between the two categorized homes. Findings of size partitioning trend through deployment of Sioutas Cascade Impactor evidenced presence of high proportion of PM and elemental concentrations within q-Acc and q-UF modes with their distribution pattern and probable emission sources conferred upon. Absence of modal peak in coarse range indicated predominance of anthropogenic emissions with presumed wash-out of coarse particles during frequent precipitation coincidental with sampling event. Seeming modal shifts for some elements (K, Cd, Zn) from q-Acc to q-UF were perceived during infiltration process. Presence of high traffic emission in homes near busy road stemmed the shifting of particles (Cu, K, Co, Zn) towards finer size (preferably q-UF mode) thus exposing residents to adverse health effects through their penetration (Finf=0.14) into indoor environment. Flat slopes (0.11) and poor correlation (8.4%) for metals in coarser range obtained through regression model hypothesized their high deposition velocities and low penetration efficiency. Our findings suggest enhanced resident exposure to fine particles (81%) especially q-UF range (37%) through indoor and outdoor (through infiltration) sources along with complexity of size distribution of airborne particles that prerequisites surplus consideration to achieve a healthier environment within residential area.

Investigation into pedestrian exposure to traffic PM around grade separations: a case study in Xi’an, China

To investigate the influence of grade separations on the concentration dynamics of particulate matter (PM) and pedestrian PM exposure rate, PM mass concentrations (PMCs) at and around a typical grade separation were measured. Using a statistical fitting method, the horizontal variation and frequency distributions for PMCs at the entrance and exit of a grade separation were investigated. The pedestrian exposure around the grade separation was quantified in terms of respiratory deposition dose (RDD) rates. The results of the case study showed that the average mass concentrations of PM10, PM2.5, and PM1 at the exit of the underpass were found to be about 19, 9, and 4% higher than those at the entrance, and the concentrations of PM10, PM2.5, and PM1 in the underpass were higher compared with those on the overpass. The average mass concentrations of PM10 (136 μg m−3), PM2.5 (67 μg m−3), and PM1 (44 μg m−3) in the underpass exceeded those on the overpass by about 14, 8, and 7%, respectively. Further analysis of the underpass revealed that all three types of PMCs decayed exponentially with increasing distance from the exit. However, for the entrance, as the distance from the entrance increased, PMCs began to drop slightly, and then rose to the maximum near the ramp. Based on the frequency histograms and corresponding fitted curves at the entrance and exit of the underpass, the rate of violation of ambient PM concentrations was assessed. The total respiratory deposition dose (RDD) rates of PM10, PM2.5, and PM1 around the grade separation were roughly 3.4, 2.8, and 2.5 times higher than those of the background, respectively. The findings of this study are a step toward understanding more environmentally friendly grade-separation design strategies.

Two notable features in PM10 data and analysis of their causes

Hourly PM10 mass concentrations were collected from 25 air quality monitoring stations in Seoul, Korea. Sixteen years of data, from 2000 to 2015, were analyzed. During that time, the annual average PM10 concentrations declined almost linearly at a rate of −1.98 μg m−3 year−1. The number of high PM10 days declined faster than did the number of low PM10 days. This indicates that the bulk of the annual average PM10 mass concentration reduction was high-level PM10 concentrations. Further analysis of this data revealed two interesting points. First, though the annual average PM10 concentrations clearly lowered for period 1 (from 2000 to 2012; −2.28 μg m−3 year−1), they remained almost unchanged at a virtually constant value for period 2 (from 2012 to 2015; −0.02 μg m−3 year−1). Second, annual average PM10 concentrations showed a large spatial concentration gradient among all monitoring stations in the early 2000s. However, the spatial concentration gradient got gradually smaller until reaching a nearly no-gradient, uniform concentration among all monitoring stations from 2010 onward. Clear PM10 concentration reduction in period 1 was driven by local emission reduction. However, its reduction was not enough in period 2. The reduction of local emissions was negated by the increase of local activities and transported particulates, as well as the formation of secondary aerosol in Seoul from emissions transported from upwind regional sources. This resulted in PM10 concentrations becoming stagnant in period 2. PM10 reduction rate in the downwind area was faster than that in the upwind area. For the first 5 years, the reduction rate in the downwind area was great. Between all the stations observed, nearly all of the concentration difference was a result of more reduction in secondary aerosol. After 2005, coarse particles and primary elemental carbon (EC) played a key role in reducing the PM10 concentration. Our findings on these two data features, and their causes, will help people to understand the most recent characteristics of particulate matters, in turn helping to update the control strategy for the continued improvement of particulate air quality in Seoul.

Predicting the frequency of extreme air quality events.

A new method for predicting the frequency of extreme air quality events is proposed. The method is based on knowing the number of times a pollutant is measured at different concentrations during a period of data collection and fitting this data to a Weibull-type function. Extrapolation of the function to higher concentrations then allows the frequency of extreme events that did not occur during the collection period to be predicted, albeit with an unspecified uncertainty. Prediction of the frequency of events over a given concentration, which was exceeded during the period of data collection, has also been performed assuming Poisson statistics. The assumption of Poisson statistics enables the provision of an uncertainty statement to accompany the prediction. The methods are trialled on a data set of daily average PM10 mass concentrations recorded at Marylebone Road in London between 2007 and 2016, inclusive. Using the method it was predicted that a daily average PM10 mass concentration of over 100 μg m-3, corresponding to the highest UK Daily Air Quality Index band, should be expected once in just over three years and this agreed well with real observations, demonstrating the utility of this new technique.

Characterization and radiative impact of dust aerosols over northwestern part of India: a case study during a severe dust storm

The present study focused on examining the impact of a severe dust storm (DS) on aerosol properties over Patiala (30.33°N, 76.4°E), a site located in the northwestern part of India during 20th–23rd March, 2012. On 20th March, average PM10 mass concentration increased abruptly from 182 to 817 µg m−3 along with significant increase in the number density of coarser particles (diameter >0.45 µm). During DS, spectral aerosol optical depth (AOD) increases significantly with more increase at longer wavelengths resulting in weak wavelength dependence (AOD at 380 nm increases by ~210 % and at 870 nm by ~270 % on 20th March). Significant decrease in Angstrom exponent (AE; α 380–870) from 0.56 to 0.11 and fine-mode fraction (FMF; PM2.5/PM10) from 0.49 to 0.25 indicates dominance of coarser particles over the station. Net short wave (SW) radiation flux has been decreased by ~20 % and single scattering albedo (SSA675) has been increased from 0.86 (19th March) to 0.90 (20th March). This observation is attributed to additional loading of scattering type aerosols on arrival of DS. Wavelength dependence of SSA reverses during DS and it increases with wavelength due to dominance of coarse-mode particles. Atmospheric aerosol radiative forcing (ATM ARF) during DS ranged from +45 to +77 W m−2, consequently heating the lower atmosphere up to 2.2 K day−1. Significant atmospheric heating rate due to severe dust storm may affect the regional atmospheric dynamics and hence the climate system.

PM10 mass concentration and oxidative capacity of moxa smoke.

The burning of moxa floss in moxibustion releases moxa smoke containing a substantial amount of particulate matter (PM10) into the environment, which has generated safety concerns about its potential health impact. Plasmid scission assay was performed using PM10 collected from moxibustion clinics. PM10 was collected in winter 2012 by burning three types of moxa floss samples in moxibustion simulation clinics, and the resulting PM10 mass concentration was calculated. Oxidative capacity of the PM10 samples was measured by plasmid scission assay and the percentage of DNA damage at dosage 500 µg ml(-1) (D500) was calculated by linear regression analysis. The average PM10 mass concentration of samples A (3 years and 3:1 ratio), B (3 years and 8:1 ratio) and C (10 years and 3:1 ratio) was 273.33, 172.22 and 168.89 μg/m(3), respectively. The D500 oxidative capacity of PM10 was on average 24.25%, 27.83% and 28.07% for samples A, B and C, respectively. No significant difference was found in the PM10-induced oxidative damage by moxa smoke produced from the three types of moxa floss. PM10 mass concentrations from the three types of moxa floss combustion exceeded internationally recommended levels. Despite so, PM10 mass concentration of moxa smoke was much lower than biomass and coal combustion and similar to that of gas combustion. The oxidative DNA damage induced by individual PM10 in moxibustion environment was lower than that reported in other environments, indicating that moxibustion-derived PM10 might not be as injurious to human health as generally assumed.

Variations in PM10, PM2.5 and PM1.0 in an Urban Area of the Sichuan Basin and Their Relation to Meteorological Factors

Daily average monitoring data for PM10, PM2.5 and PM1.0 and meteorological parameters at Chengdu from 2009 to 2011 are analyzed using statistical methods to replicate the effect of urban air pollution in Chengdu metropolitan region of the Sichuan Basin. The temporal distribution of, and correlation between, PM10, PM2.5 and PM1.0 particles are analyzed. Additionally, the relationships between particulate matter (PM) and certain meteorological parameters are studied. The results show that variations in the average mass concentrations of PM10, PM2.5 and PM1.0 generally have the same V-shaped distributions (except for April), with peak/trough values for PM average mass concentrations appearing in January/September, respectively. From 2009 to 2011, the inter-annual average mass concentrations of PM10, PM2.5 and PM1.0 fall year on year. The correlation coefficients of daily concentrations of PM10 with PM2.5, PM10 with PM1.0, and PM2.5 with PM1.0 were high, reaching 0.91, 0.83 and 0.98, respectively. In addition, the average ratios of PM2.5/PM10, PM1.0/PM10 and PM1.0/PM2.5 were 85%, 78% and 92%, respectively. From this, fine PM is determined to be the principal pollutant in the Chengdu region. Except for averaged air pressure values, negative correlations exist between other meteorological parameters and PM. Temperature and air pressure influenced the transport and accumulation of PM by affecting convection. Winds promoted PM dispersion. Precipitation not only accelerated the deposition of wet PM, but also inhibited surface dust transport. There was an obvious correlation between PM and visibility; the most important cause of visibility degradation was due to the light extinction of aerosol particles.