Particulate Matter Size Research Articles

Geometric configurations of particulate matter in terrestrial solutions of a temperate beech forest

The heterogeneous nature of the size and shape of particulate matter (PM) deposited onto forest canopies is acknowledged. However, it is uncertain how PM interacts with the forest canopy and how it is transported and cycled via the hydrological processes of throughfall and stemflow. To improve our understanding of particulate cycling in forested watersheds, this study quantifies the geometric configuration of PM in bulk precipitation, throughfall, stemflow, and upper soil (Oa horizon) solution in both leafed and leafless periods in a European beech (Fagus sylvatica L.) forest in Germany. Circular equivalence diameter, circularity, elongation ratio, perimeter-to-area ratio, and fractal dimension were calculated for all 43,278 individual particulates in bulk precipitation, throughfall, stemflow, and Oa solutions. Loss on ignition measurements were also conducted to determine the organic matter content of the particulates. From a physical point of view, the opposite trends for circular equivalence diameter and perimeter-to-area ratio of PM between stemflow or throughfall and bulk precipitation during both leafless and leafed periods were the most striking. For bulk precipitation, the PM's mean circular equivalence diameter was significantly larger in the leafless period than the leafed period, with the reverse observed for throughfall and stemflow. Mean perimeter-to-area ratios (μm−1) of PM of both stemflow and throughfall were significantly larger in the leafless period than the leafed period. The opposite trend was observed for bulk precipitation and Oa solution. The percent organic matter of PM was not statistically significantly different across solutions or canopy state. Our results indicate that the differential routing of PM through the canopy indeed influences the geometry of PM among solution types as compared to the bulk precipitation. The effects of these changes on the chemistry of the PM and its impact of particulate cycling, and the impacts of shifting seasonality with climate change, warrants further investigation.

Concept Development and Field Testing of Wireless Outdoor Indicator System for Use in Monitoring Exposures at Work among Malaysian Traffic Police.

Real-time exposure air monitoring is essential to protect the respiratory health of the Malaysian traffic police. However, the data from monitoring stations have been inadequate to provide accurate information about their exposure. This report describes the conceptual design of a wireless exposure indicator system, and then evaluates the field performance of the system by collocation. The study tested the accuracy of particulate matter size 2.5 (PM2.5), carbon monoxide (CO), and nitrogen dioxide (NO2) by comparing the measurements from the prototype with the measurements from reference instruments. The field testing found that the data tested were significantly correlated with each other (PM2.5-rs = 0.207, p = 0.019; NO2-rs = 0.576, p = 0.02 and CO-rs = 0.545, p = 0.04). The prototype proved to be successful as it can compute and transmit real-time monitoring data on the level of exposure to harmful air.

Measurement of Fine/Ultrafine Dust Using Lenticular Fiber-Based Particulate Measurement Devices

Measurement of particulate matter (PM), i.e., fine/ultrafine dust, is important for monitoring our surrounding environment. We demonstrate the fabrication of lenticular fiber-based fine/ultrafine dust measurement devices for monitoring the density and size of dust. The plano-convex lenticular fibers were fabricated by the CO2 laser polishing technique. The optical lens, used in the conventional light scattering-based fine/ultrafine dust measurement devices, was replaced by a plano-convex lenticular optical fiber to reduce the size and complexity of the dust measurement device. We utilized a light-emitting diode as the light source of the fine/ultrafine dust density measurement device. The fabricated device could indicate the dust density level (good, normal, bad, and very bad) according to the Korean standard. To estimate the size of the dust particulates, we fabricated a dust size measurement device that consists of a compact laser diode, a lenticular fiber, and a photodetector. We are successful in estimating the size of both fine and ultrafine PMs by detecting the power of the scattered light coming from the dust particulates. The dust size down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.9 \mu \text{m}$ </tex-math></inline-formula> was detected using our dust measurement device. Our proposed dust measurement devices are simple, small, and cost-effective and can be considered as a candidate for portable applications.

Air pollution associated with hospital visits for mental and behavioral disorders in Northeast China.

Related studies have found that air pollution is an important factor affecting mental and behavioral disorders. Thus, we performed this time-series study to evaluate the relationship between short-term exposure to ambient air pollutants and visits to hospital by patients with mental and behavioral disorders in northeastern China. We used quasi-Poisson regression models and generalized additive models to probe the links between air pollution and mental and behavioral disorders. The possible influences were also explored stratified by season, age and gender. We found that sulfur dioxide (SO2) had a cumulative effect on mental and behavioral disorders at lag04-lag07 and had the greatest effect at lag07 [Relative risk (RR) = 1.068, 95%CI = 1.021-1.117]. Particulate matter of size 2.5 μm (PM2.5) and SO2 had a cumulative effect on depression and both had the largest effect at lag07 (RR = 1.021, 95%CI = 1.002-1.041; RR = 1.103, 95%CI = 1.032-1.178); SO2 also had a cumulative effect on anxiety disorders, with the largest effect at lag06 (RR = 1.058, 95%CI = 1.009-1.110). In the stratified analysis, people are more susceptible in the cold season compared to the warm season and females and the 18-60-year age group are more sensitive to air pollutants. It is suggested to strengthen management and preventive measures to decrease air pollution exposure. This study found an association between increased concentrations of air pollutants and increased outpatient visits for mental and behavioral disorders. We recommend that preventive and protective measures should be strengthened in an effort to reduce exposure to air pollution in order to maintain physical and mental health.

Simultaneous Quantification of Real-World Elemental Contributions from the Exhaust and Non-Exhaust Vehicular Emissions Using Road Dust Enrichment Factor-Elemental Carbon Tracer Method (EFECT)

Emission control regulations have been essential in reducing vehicular exhaust emissions. However, the contribution of exhaust and non-exhaust emissions to ambient particulate matter (PM) has not yet been accurately quantified due to the lack of standardized sampling and measurement methods to set regulations. The identified sources and the source profiles generated have not been comparable as none of the emission data collection techniques and the receptor models applied in the literature have produced a standard or reference method to simultaneously identify and quantify the non-exhaust emission sources. This study utilized and thoroughly characterized PM samples including 32 major and trace elements from a mixed fleet in a mountain highway tunnel atmosphere in Bolu, Türkiye. This work proposed a two-stage, simple, and robust method based on road dust enrichment factor (EF) and elemental carbon (EC) tracer methods (EFECT) for the identification and prediction of the exhaust (exh), and non-exhaust (n-exh) emissions in PM. The indicated method revealed that road dust resuspension emissions are the most significant contributor to the concentrations of crustal elements. This method was used successfully to determine the real-world elemental contributions of road dust resuspension (rdrs), emissions (em), exhaust (exh), and non-exhaust (n-exh) emission sources to the elemental concentrations in PM samples. This study provided significant insights into generating actual source profiles, source-specific emission factors, and the source apportionment results for vehicular emission sources worldwide. Considering this, PM data of any particle size fraction (PM10, PM10-2.5, and PM2.5, for example) can be used as input for the EFECT, provided that the data include the analytical results of elemental carbon in both the atmospheric PM and road dust samples having similar PM sizes.

The oxidative potential of airborne particulate matter in two urban areas of Chile: More than meets the eye

Oxidative potential (OP) has gained attention as a parameter that can reveal the ability of different properties of particulate matter (PM) to generate reactive oxygen species (ROS) as one single value. Moreover, OP is also believed to be a predictor of toxicity and hence the health effects of PM. This study evaluated the OP of PM10, PM2.5,and PM1.0samples using dithiothreitol assays in two cities of Chile (Santiago and Chillán). The results showed that the OP was different between cities, PM size fractions, and seasons. Additionally, OP was strongly correlated with certain metals and meteorological variables. Higher mass-normalized OP was observed during cold periods in Chillán and warm periods in Santiago and was associated with PM2.5 and PM1. On the other hand, volume-normalized OP was higher during winter in both cities and for PM10. Additionally, we compared the OP values to the Air Quality Index (AQI) scale and found cases of days that were classified as having “good” air quality (supposed to be less harmful to health) showing extremely high OP values that were similar to those on days that were classified as “unhealthy”. Based on these results,we suggest using the OP as a complementary measure to the PM mass concentration because it includes important new information related to PM properties and compositions that could help improvecurrent air quality management tools.

Health effects of air pollution on maternal preeclampsia in a rural area of China: A population-based cohort study

Few studies have focused on the effects of air pollutants on maternal preeclampsia and sub-types in rural areas. In this study, a time-dependent Cox proportional hazards model was used to explore trimester-specific and entire pregnancy concentrations of pollutants and preeclampsia in Liuyang rural area of China from 2017 to 2019, and to examine whether season and parity could modify the effects. 36,776 participants were included, of whom 968 (2.63%) were diagnosed with preeclampsia (mild 448; severe 520). Exposure to PM2.5 was significantly associated with mild preeclampsia (HR 1.12–1.90) in the adjusted models for the overall pregnancy. Exposure to ozone had the opposite effect. SO2 exposure in the third trimester was positively associated with mild preeclampsia (HR 1.14–1.35). Exposure to PM10 was associated with a 2% risk of severe preeclampsia in the adjusted models for the first trimester. Mild preeclampsia was positively associated with exposure to NO2 and SO2 in the third trimester in the summer conception, and both sizes of particulate matter in the first trimester in the winter. The risk of preeclampsia was increased by exposure to SO2 in the third trimester for nulliparous women (HR 1.30, 95% CI: 1.12–1.52), PM10 in the first trimester for primiparous women (HR 1.03, 95% CI: 1.01–1.04), and both sizes of particulate matter in the second trimester for multiparous women (HR 1.09, 95% CI: 1.02–1.17; HR 1.07, 95% CI: 1.02–1.13). The study adds to evidence on the association between maternal exposure to air pollutants and different types of preeclampsia.

Size-Resolved Field Performance of Low-Cost Sensors for Particulate Matter Air Pollution.

Particulate matter (PM) air pollution is a major health hazard. The health effects of PM are closely linked to particle size, which governs its deposition in (and penetration through) the respiratory tract. In recent years, low-cost sensors that report particle concentrations for multiple-sized fractions (PM1.0, PM2.5, PM10) have proliferated in everyday use and scientific research. However, knowledge of how well these sensors perform across the full range of reported particle size fractions is limited. Unfortunately, erroneous particle size data can lead to spurious conclusions about exposure, misguided interventions, and ineffectual policy decisions. We assessed the linearity, bias, and precision of three low-cost sensor models, as a function of PM size fraction, in an urban setting. Contrary to manufacturers' claims, sensors are only accurate for the smallest size fraction (PM1). The PM1.0-2.5 and PM2.5-10 size fractions had large bias, noise, and uncertainty. These results demonstrate that low-cost aerosol sensors (1) cannot discriminate particle size accurately and (2) only report linear and precise measures of aerosol concentration in the accumulation mode size range (i.e., between 0.1 and 1 μm). We recommend that crowdsourced air quality monitoring networks stop reporting coarse (PM2.5-10) mode and PM10 mass concentrations from these sensors.

Removal, migration, and distribution of naphthalene in bioretention facilities: the influences of particulate matter.

Particulate matter (PM), as an important carrier of carrying and transporting runoff pollutants, can significantly affect the behavior and removal efficiency of pollutants in bioretention facilities. In order to control the pollution caused by naphthalene in bioretention facilities, the removal efficiency and migration characteristics of naphthalene were systematically investigated under the influences of PM. The results showed that the removal efficiency of naphthalene was 74 ~ 97% in bioretention facilities under the influences of PM. With the higher concentration, the lower rainfall return period, and the longer antecedent drying period, the removal efficiency of naphthalene in each medium layer were higher. Furthermore, the PM could increase the naphthalene adsorption capacity onto medium in the first 10cm depth, which showed more than 80% removal efficiency and lower mobility of naphthalene. The removal efficiency of naphthalene was significantly higher (90 ~ 97%), when the particle size and concentration of PM were 0 ~ 45μm and 500mg/L, respectively. This study investigated the important role of PM for naphthalene removal in bioretention facilities, and provided effective guidelines for runoff pollution control, design of stormwater facilities, and assessment risk of naphthalene.

GEOCHEMISTRY AND MINERAL CONTENT OF ASH FLOW FROM THE MONTSERRAT SOUFRIERE HILLS VOLCANO

The Soufriere Hills Volcano of Montserrat has ancient origins and roared back to life in 1995 wreaking severe havoc and damage to the inhabitants, geography, and ecosystems of the Island. The pyroclastic ash flow reached temperatures of 1500 °F and progressed down the hillsides at speeds of 80 mph, causing incineration and virtual destruction of everything in its path, while the gaseous and particulate laden plume reached altitudes of 35,000 feet, impacting air quality and aircraft navigation. The local health authorities recommended masking and physical protection from any potentially harmful effects from the ash to all residents who remained on Island following the 1995 eruption. Volcanic ash can be an irritant to exposed skin and respiratory surfaces upon contact due in part to the sharp and jagged nature of the microcrystalline particulate matter. In addition, the minute size of the smallest particulate matter can impact deep into the unprotected respiratory tree in humans and animals, potentially causing severe respiratory injury. The composition and physicochemical nature of the ash was largely unknown in 1995 and subsequent years. The current study was designed to determine the geochemical composition of the ash. Samples of ash were collected from 7 locations and water samples from three free flowing creeks in Montserrat and indicated that the creek water was acidic in nature. The mean pH of water was 5.2, while the ash showed abundant levels of Iron, Phosphorus, Calcium, Magnesium, Sodium, Aluminum, and sulfur, in addition to lower concentrations of potassium, boron, copper and zinc and intermediate concentrations of Manganese and was devoid of toxic minerals including lead and mercury. The emergence of acute respiratory issues was not found to exceed similar events in other healthy populations including individuals relocated to the UK. In conclusion, direct human and animal exposure to Montserrat volcanic ash was deemed non-harmful to humans when adequate protective measures including masking and exposure precautions were undertaken, while the rich mineral content of the ash can provide a rich source of micronutrient mineralization to soils and surrounding seawaters and support vigorous revegetation and recovery of affected land and sea zones throughout the island community.

Accelerated settling velocity of airborne particulate matter on hairy plant leaves

Phytoremediation has emerged as an ecofriendly technique to reduce hazardous particulate matter (PM) in the air. Although previous studies have conducted statistical analyses to reveal PM removal capabilities of various plant species according to their leaf characteristics, the underlying physical mechanism of PM adsorption of plants remains unclear. Conventional methodologies for measuring PM accumulation usually require long-term field tests and provide limited understanding on PM removal effects of individual leaf traits of various plants. In this study, we propose a novel methodology which can compare the electrostatic interactions between PMs and plant leaves according to their trichome structures by using digital in-line holographic microscopy (DIHM). Surface characteristics of Perilla frutescens and Capsicum annuum leaves are measured to examine electrostatic effects according to the morphological features of trichomes. 3D settling motions of PMs near the microstructures of trichomes of the two plant species are compared in detail. To validate the PM removal effect of the hairy microstructures, a polydimethylsiloxane (PDMS) replica model of a P. frutescens leaf is fabricated to demonstrate accelerated settling velocities of PMs near trichome-like microstructures. The size and electric charge distributions of PMs with irregular shapes are analyzed using DIHM. Numerical simulation of the PM deposition near a trichome-like structure is conducted to verify the empirical results. As a result, the settling velocities of PMs on P. frutescens leaves and a PDMS replica sample are 12.11 ± 1.88% and 34.06 ± 4.19% faster than those on C. annuum leaves and a flat PDMS sample, respectively. These findings indicate that the curved microstructures of hairy trichomes of plant leaves increase the ability to capture PMs by enhancing the electric field intensity just near trichomes. Compared with conventional methods, the proposed methodology can quantitatively evaluate the settling velocity of PMs on various plant leaves according to the morphological structure and density of trichomes within a short period of time. The present research findings would be widely utilized in the selection of suitable air-purifying plants for sustainable removal of harmful air pollutants in urban and indoor environments.

Histology, prevalence, and environmental sources for pulmonary silicates depositions in domestic and wild animals.

The source and significance of pulmonary silicate crystals in animals and people are poorly understood. To estimate the prevalence and characterize the pulmonary crystalline material in animals from St. Kitts, tissue samples from dogs, horses, cattle, sheep, goats, pigs, chickens, mongooses, and monkeys were examined by light microscopy, scanning electron microscopy with energy-dispersive x-ray analysis (SEM/EDXA), and x-ray diffraction. Crystalline material was seen in 201 of 259 (77.6%) lung samples as perivascular and interstitial accumulations of heterogeneous crystalline particulate material, free or within macrophages (silicate-laden macrophages [SLMs]), mostly lacking evidence of chronic inflammation or fibrosis. The crystalline material was birefringent, basophilic on acid-fast, and composed of silicas on SEM/EDXA. Mongooses (100%) and monkeys (98%) had the highest prevalence of SLM, followed by cattle and chickens. Lesions were graded on a 3-point scale based on the histologic location and extent of silicates and SLM and were significantly more severe in mongooses (median = 3) than in monkeys (median = 2), dogs (median = 2), and chickens (median = 1). On EDXA, the crystalline material from lungs, air, and topsoil was composed of silicon, oxygen, aluminum, and iron, with a particulate matter size between 2.5 and 10 µm. We hypothesize Saharan dust, volcanic ash, topsoil, and rock quarry dust are potential sources of siliceous dust inhalation and SLM accumulations lacking chronic inflammation (silicosis); dust generation may be potentiated by road vehicle or wind suspension. Future investigations are warranted on the role of silicate inhalation and respiratory comorbidities in people, with monkeys, mongooses, or chickens serving as possible sentinels for exposure.

Factors affecting indoor environmental air quality of non-smoking residences in Perth, Western Australia

This study investigated associations between a range of indoor air pollutants with household characteristics in 111 non-smoking residences located in Perth, Western Australia. Overall, the mean 24-hour indoor concentrations for PM10 and PM2.5 were below and above the World Health Organisation (WHO) (ambient) guideline values (GV) of 45 µg/m3 and 15 µg/m3, respectively. Concentrations of measured gases were low, other than nitrogen dioxide (NO2) which recorded a mean 24-hour concentration above the WHO GV (0.013ppm). Higher concentrations of total volatile organic compounds (TVOC) and carbon dioxide (CO2) were observed as the number of household occupants increased. The type of heating and/or cooling appliances used was associated with higher concentrations of TVOC, CO2, carbon monoxide (CO), NO2 and all size fractions of particulate matter (PM). Households that were opened daily for fresh air recorded higher concentrations of all PM size fractions and NO2 when compared to those that were infrequently aired. These findings contribute to a better understanding of household characteristics that influence indoor air quality (IAQ) in homes where cigarette smoke, a significant contributor to residential air pollution, has been eliminated. These results are useful for modifying some behavioural choices by home occupants and can also inform meaningful risk mitigation strategies aimed at improving IAQ in residential settings.

Association between ambient cold exposure and mortality risk in Shandong Province, China: Modification effect of particulate matter size.

Numerous studies have reported the modification of particulate matters (PMs) on the association between cold temperature and health. However, it remains uncertain whether the modification effect may vary by size of PMs, especially in Shandong Province, China where the disease burdens associated with cold temperature and PMs are both substantial. This study aimed to examine various interactive effects of cold exposure and ambient PMs with diameters ≤1/2.5 μm (PM1 and PM2.5) on premature deaths in Shandong Province, China. In the 2013-2018 cold seasons, data on daily mortality, PM1 and PM2.5, and weather conditions were collected from the 1822 sub-districts of Shandong Province. A time-stratified case-crossover study design was performed to quantify the cumulative association between ambient cold and mortality over lag 0-12 days, with a linear interactive term between temperature and PM1 and PM2.5 additionally added into the model. The mortality risk increased with temperature decline, with the cumulative OR of extreme cold (-16.9°C, the 1st percentile of temperature range) being 1.83 (95% CI: 1.66, 2.02), compared with the minimum mortality temperature. The cold-related mortality risk was 2.20 (95%CI: 1.83, 2.64) and 2.24 (95%CI: 1.78, 2.81) on high PM1 and PM2.5 days, which dropped to 1.60 (95%CI: 1.39, 1.84) and 1.60 (95%CI: 1.37, 1.88) on low PM1 and PM2.5 days. PM1 showed greater modification effect for per unit concentration increase than PM2.5. For example, for each 10?g/m3 increase in PM1 and PM2.5, the mortality risk associated with extreme cold temperature increased by 7.6% (95% CI: 1.3%, 14.2%) and 2.6% (95% CI: -0.7%, 5.9%), respectively. The increment of smaller PMs' modification effect varied by population subgroups, which was particularly strong in the elderly aged over 75 years and individuals with middle school education and below. Specific health promotion strategies should be developed towards the greater modification effect of smaller PMs on cold effect.

Effects of E-Cigarette Liquid Ratios on the Gravimetric Filter Correction Factors and Real-Time Measurements.

Electronic cigarettes (ECIGs) generate high concentrations of particulate matter (PM), impacting the air quality inhaled by humans through secondhand exposure. ECIG liquids are available commercially and some users create their own "do-it-yourself" liquids, and these liquids often vary in the amounts of their chemical ingredients, including propylene glycol (PG) and vegetable glycerin (VG). Previous studies have quantified PM concentrations in ECIG aerosol generated from liquids containing different PG/VG ratios. However, the effects of these ratios on aerosol instrument filter correction factors needed to measure PM concentrations accurately have not been assessed. Thus, ECIG aerosol filter correction factors for multiple aerosol instruments (SMPS + APS, MiniWRAS, pDR, and SidePak) were determined for five different PG/VG ratios 1) 0PG/100VG, 2) 15PG/85VG, 3) 50PG/50VG, 4) 72PG/28VG, and 5) 90PG/10VG and two different PM sizes, PM1 (1 μm and smaller) and PM2.5 (2.5 μm and smaller). ECIG aerosols were generated inside a controlled exposure chamber using a diaphragm pump and a refillable ECIG device for all the ratios. In addition, the aerosol size distribution and mass median diameter were measured for all five ECIG ratios. PM2.5 correction factors (5-7.6) for ratios 1, 2, 3, and 4 were similar for the SMPS + APS combined data, and ratios 1, 2, 3 were similar for the MiniWRAS (~2), pDR (~0.5), and SidePak (~0.24). These data suggest different correction factors may need to be developed for aerosol generated from ECIGs with high PG content. The higher correction factor values for the 90PG/10VG ratio may have resulted from greater PG volatility relative to VG and sensor losses. The correction factors (ratios 1-4) for PM2.5 were SMPS + APS data (4.96-7.62), MiniWRAS (2.02-3.64), pDR (0.50-1.07), and SidePak (0.22-0.40). These data can help improve ECIG aerosol measurement accuracy for different ECIG mixture ratios.

Characterizing metals in particulate pollution in communities at the fenceline of heavy industry: combining mobile monitoring and size-resolved filter measurements.

Exposures to metals from industrial emissions can pose important health risks. The Chester-Trainer-Marcus Hook area of southeastern Pennsylvania is home to multiple petrochemical plants, a refinery, and a waste incinerator, most abutting socio-economically disadvantaged residential communities. Existing information on fenceline community exposures is based on monitoring data with low temporal and spatial resolution and EPA models that incorporate industry self-reporting. During a 3 week sampling campaign in September 2021, size-resolved particulate matter (PM) metals concentrations were obtained at a fixed site in Chester and on-line mobile aerosol measurements were conducted around Chester-Trainer-Marcus Hook. Fixed-site arsenic, lead, antimony, cobalt, and manganese concentrations in total PM were higher (p < 0.001) than EPA model estimates, and arsenic, lead, and cadmium were predominantly observed in fine PM (<2.5 μm), the PM fraction which can penetrate deeply into the lungs. Hazard index analysis suggests adverse effects are not expected from exposures at the observed levels; however, additional chemical exposures, PM size fraction, and non-chemical stressors should be considered in future studies for accurate assessment of risk. Fixed-site MOUDI and nearby mobile aerosol measurements were moderately correlated (r ≥ 0.5) for aluminum, potassium and selenium. Source apportionment analyses suggested the presence of four major emissions sources (sea salt, mineral dust, general combustion, and non-exhaust vehicle emissions) in the study area. Elevated levels of combustion-related elements of health concern (e.g., arsenic, cadmium, antimony, and vanadium) were observed near the waste incinerator and other industrial facilities by mobile monitoring, as well as in residential-zoned areas in Chester. These results suggest potential co-exposures to harmful atmospheric metal/metalloids in communities surrounding the Chester-Trainer-Marcus Hook industrial area at levels that may exceed previous estimates from EPA modeling.

Estimating causal links of long-term exposure to particulate matters with all-cause mortality in South China

BackgroundThe association between long-term particulate matter (PM) exposure and all-cause mortality has been well-documented. However, evidence is still limited from high-exposed cohorts, especially for PM1 which is smaller while more toxic than other commonly investigated particles. We aimed to examine the potential casual links of long-term PMs exposure with all-cause mortality in high-exposed areas. MethodsA total of 580,757 participants in southern China were enrolled during 2009–2015 and followed up to 2020. The annual average concentration of PM1, PM2.5, and PM10 at 1 km2 spatial resolution was assessed for each residential address through validated spatiotemporal models. We used marginal structural Cox models to estimate the PM-mortality associations which were further stratified by sociodemographic, lifestyle factors and general exposure levels. Results37,578 deaths were totally identified during averagely 8.0 years of follow-up. Increased exposure to all 3 PM size fractions were significantly associated with increased risk of all-cause mortality, with hazard ratios (HRs) of 1.042 (95 % confidence interval (CI): 1.037–1.046), 1.031 (95 % CI: 1.028–1.033), and 1.029 (95 % CI: 1.027–1.031) per 1 μg/m3 increase in PM1, PM2.5, and PM10 concentrations, respectively. We observed greater effect estimates among the elderly (age ≥ 65 years), unmarried participants, and those with low education attainment. Additionally, the effect of PM1, PM2.5, and PM10 tend to be higher in the low-exposure group than in the general population. ConclusionsWe provided comprehensive evidence for the potential causal links betweenlong-term PM exposureand all-cause mortality, and suggested stronger links for PM1compared to large particles and among certain vulnerable subgroups.

Physical and chemical analysis of Beirut ammonium nitrate blast: A concern of particulate matter in atmosphere

Chemical disasters are caused by improper management, handling, transportation, and sudden accidents. The massive explosion of ammonium nitrate silo in the port of Beirut on August 4, 2020, has threatened the world with the loss of 220 people, about 6500 injuries, huge property loss, and environmental contamination. This paper aims to summarize the major ammonium nitrate accidents in the past 100 years in the world. We analyzed the accidents in terms of frequency, causes, property loss, and deaths. We reported 43 accidents in which 7 accidents triggered more than 100 casualties. Altogether seven terrorist attacks with ammonium nitrate are reported leading to the death of 411 people and huge loss of assets. The explosion releases a large amount of energy and produces a variety of gases along with nitrogen oxides, ammonia, and a lot of particulate matter (PM), which significantly contributes to air pollution. The size and amount of PM imposes negative impact on environment like low visibility, decreased solar radiation and adverse health impacts like chronic respiratory, pulmonary, cardiovascular, and other human diseases. Proper management and safety measures with stringent regulations at national and international level is warranted for the safe and sustainable use of industrial chemicals.

Identifying Common Trees and Herbaceous Plants to Mitigate Particulate Matter Pollution in a Semi-Arid Mining Region of South Africa

Plants provide long-term and sustainable solutions to mitigate particulate matter (PM) pollution in urban environments. We evaluated total, fine, coarse and large particle trapping abilities of an equal number of common trees (Carica papaya, Citrus limon, Moringa oleifera, Ozoroa paniculosa, Peltophorum africanum, Psidium guajava) and herbaceous species (Argemone ochroleuca, Catharanthus roseus, Gomphocarpus fruticosus, Ipomoea batatas, Senna italica, Tribulus terrestris) to identify dust accumulators for Sekhukhuneland, a mining–smelting region of South Africa where desertification is becoming problematic. Scanning electron microscopy techniques were used to count and measure particles and relate leaf surface micromorphology to dust accumulation. Three tree and three herbaceous species showed superior dust collection capacity (G. fruticosus &gt; P. guajava &gt; I. batatas &gt; O. paniculosa &gt; C. roseus &gt; M. oleifera). Variations in accumulation of PM sizes were noted among these six species and between adaxial and abaxial leaf surfaces. Compared with large PM, all plants accumulated more fine and coarse fractions which are respirable and thus hazardous to human health. Leaf surface roughness, epicuticular wax and epidermal glands improved dust accumulation. The six preferred plants may serve as forerunner species to abate PM pollution in Sekhukhuneland and other arid regions facing similar climate change and pollution challenges.

Role of morphology and chemical composition of PM for particle deposition in human respiratory system: A case study over megacity-Delhi

Morphology and chemical composition altogether determine the fate of atmospheric particulate matter(PM) deposition and inhalation. Site-wise(#20 sites) and cumulative variations in morphology and chemical composition of PM5 in Delhi showed dominance of non-spherical (sharp-edged, angular and flattened) particles followed by spherical ones, rich in elements like C, O, S, N, Al, Si, Cu, Ca, Na, Cl, Fe, Ni, Cr, Zn, Hg, Pb, Mo, etc. having potential health effects. #2650 individual particles analyzed for the morphological parameters like aspect ratio(AR), circularity factor(CIR), surface equivalent radius(SER) and area. Dominant AR and SER values found between ≥1–1.60 and > 0–0.50 μm, respectively showing dominance of non-spherical and fine-size particles in Delhi. The Multiple Path Particle Dosimetry (MPPD) Model used to study variations in deposition potential (regional deposition, lobar deposition, mass deposition and mass flux) of different PM sizes (PM0.4, PM1, PM2.5 and PM5) at different AR values which suggested that AR is an important input parameter of health models to get realistic and unbiased output health data. In addition, study revealed higher coarse particles deposition in the head region affecting upper respiratory tract with their non-spherical shapes whereas higher fine particles deposition in TB and pulmonary regions affecting inner parts of the lungs.