Fine Particle Mass Concentrations Research Articles

Elemental composition of fine and coarse particles across the greater Los Angeles area: Spatial variation and contributing sources

The inorganic components of particulate matter (PM), especially transition metals, have been shown to contribute to PM toxicity. In this study, the spatial distribution of PM elements and their potential sources in the Greater Los Angeles area were studied. The mass concentration and detailed elemental composition of fine (PM2.5) and coarse (PM2.5-10) particles were assessed at 46 locations, including urban traffic, urban community, urban background, and desert locations. Crustal enrichment factors (EFs), roadside enrichments (REs), and bivariate correlation analysis revealed that Ba, Cr, Cu, Mo, Pd, Sb, Zn, and Zr were associated with traffic emissions in both PM2.5 and PM2.5-10, while Fe, Li, Mn, and Ti were affected by traffic emissions mostly in PM2.5. The concentrations of Ba, Cu, Mo, Sb, Zr (brake wear tracers), Pd (tailpipe tracer), and Zn (associated with tire wear) were higher at urban traffic sites than urban background locations by factors of 2.6–4.6. Both PM2.5 and PM2.5-10 elements showed large spatial variations, indicating the presence of diverse emission sources across sampling locations. Principal component analysis extracted four source factors that explained 88% of the variance in the PM2.5 elemental concentrations, and three sources that explained 86% of the variance in the PM2.5-10 elemental concentrations. Based on multiple linear regression analysis, the contribution of traffic emissions (27%) to PM2.5 was found to be higher than mineral dust (23%), marine aerosol (18%), and industrial emissions (8%). On the other hand, mineral dust was the dominant source of PM2.5-10 with 45% contribution, followed by marine aerosol (22%), and traffic emissions (19%). This study provides novel insight into the spatial variation of traffic-related elements in a large metropolitan area.

A satellite-derived, ground-measurement-independent monthly PM2.5 mass concentration dataset over China during 2000 - 2015

ABSTRACT Following the accelerated development of urbanization and industrialization, atmospheric particulate matter has become a significant threat to public health globally. Environmental health studies usually use the mass concentration of fine particles (PM2.5) as a base data to predict the health risks of particulate exposure. However, PM2.5 data from ground monitoring stations in China has not been provided until January 2013 by the Ministry of Environmental Protection of China. Hence, an alternative dataset of PM2.5 spatiotemporal distributions extending to years earlier than 2013 is urgently needed, which is of great significance to atmospheric environment assessment and pollution prevention and control. Atmospheric aerosol products by the moderate-resolution imaging spectroradiometer (MODIS) have been released since 2000, which provides the possibility to reconstruct historical PM2.5. However, most current methods do not have the ability to estimate PM2.5 mass concentration independently of ground observations. The PM2.5 mass concentration data set produced by PM2.5 remote sensing (PMRS) model based on physical processes does not depend on the ground observations, and also is not affected by the uncertainty of model emission sources or the completeness of chemical reaction mechanism. These ensure that the point-by-point validation for PM2.5 mass concentration data is more convincing, and the dataset can also be further used for model assimilation and artificial intelligence training to improve their predictions. In this study, we calculate the monthly PM2.5 mass concentration near the ground over land of China using aerosol inversion products (aerosol optical depth and fine-mode fraction) of MODIS and meteorological data (boundary layer height & relative humidity) provided by the Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2) data set. The results show that, in China, 6 pollution centers mainly concentrated in the central and eastern regions. The highest PM2.5 mass concentration occurred in winter, whereas the pollution range was larger in summer. There are 63.4% of validation sites with biases within ±20 μg m−3, and the expected error is as ±(15 μg m−3 + 30%) enveloped by the monthly mean PM2.5 mass concentrations. The monthly PM2.5 is stored as NETCDF format, with a spatial resolution of 1°×1°. The published data is available in http://www.dx.doi.org/10.11922/sciencedb.j00076.00061.

Chemical characteristics of size-resolved fog water at an urban site in Nanjing and the summit of Mt. Lu, East China

The chemical characteristics of fog water are closely related to the droplet size. This study used a three-stage Caltech Active Strand Cloud Collector (CASCC) to collect 170 size-resolved fog samples from eight fog events in the winter of 2013–2017 at an urban site in Nanjing and the summit of Mt. Lu. The pH, electrical conductivity (EC), and inorganic ion concentration were analyzed, and the sources of pollutants in size-dependent droplets were discussed according to the local emission source type. The pH, EC, total ion concentration (TIC), and ion composition of fog water at Nanjing were dependent on the droplet size. The TIC of fog water at Nanjing was approximately 10 times that measured at Mt. Lu. The concentration of different chemical species in the droplet was also size-dependent: Ca2+ concentration was higher in larger droplets with the diameter (D) ≥ 22 μm, whereas SO42−, NO3−, and NH4+ concentrations were higher in smaller droplets with D ranging 4–16 μm. The ion concentration of fog water at Mt. Lu first decreased then increased as the fog developed. Owing to the faster drop rate of larger droplets, coarse particles (2.5–10 μm) exhibited a faster response to fog removal, and the final mass concentration of fine particles (<2.5 μm) decreased the most due to competition between deposition and gravity. Different pollution sources exhibited different contribution rates to the chemical components of size-dependent droplets. Soil sources mainly affected the Ca2+ content of large droplets, whereas industrial sources and vehicles affected the NO3− and SO42− concentrations of medium and small droplets. Soil sources, industrial sources, and vehicles were the main sources of fog water at the urban site in Nanjing, whereas industrial sources, vehicles, soil sources, biomass combustion, and secondary aerosols were the main sources of fog water at the summit of Mt. Lu.

Acute health effects from exposure to indoor ultrafine particles-A randomized controlled crossover study among young mild asthmatics.

Particulate matter is linked to adverse health effects, however, little is known about health effects of particles emitted from typical indoor sources. We examined acute health effects of short-term exposure to emissions from cooking and candles among asthmatics. In a randomized controlled double-blinded crossover study, 36 young non-smoking asthmatics attended three exposure sessions lasting 5h: (a) air mixed with emissions from cooking (fine particle mass concentration): (PM2.5 : 96.1μg/m3 ), (b) air mixed with emissions from candles (PM2.5 : 89.8μg/m3 ), and c) clean filtered air (PM2.5 : 5.8μg/m3 ). Health effects (spirometry, fractional exhaled Nitric Oxide [FeNO], nasal volume and self-reported symptoms) were evaluated before exposure start, then 5 and 24h after. During exposures volatile organic compounds (VOCs), particle size distributions, number concentrations and optical properties were measured. Generally, no statistically significant changes were observed in spirometry, FeNO, or nasal volume comparing cooking and candle exposures to clean air. In males, nasal volume and FeNO decreased after exposure to cooking and candles, respectively. Participants reported additional and more pronounced symptoms during exposure to cooking and candles compared to clean air. The results indicate that emissions from cooking and candles exert mild inflammation in asthmatic males and decrease comfort among asthmatic males and females.

Measuring indoor fine particle concentrations, emission rates, and decay rates from cannabis use in a residence

Fifteen states have legalized the sales of recreational marijuana, and California has the largest sales of any state. Cannabis is most often smoked indoors, but few measurements have been made of fine particle mass concentrations produced by secondhand cannabis smoke in indoor settings. We conducted 60 controlled experiments in a 43 m 3 room of a residence, measuring PM 2.5 concentrations, emission rates, and decay rates using real-time monitors designed to measure PM 2.5 mass concentrations. We also measured the room's air exchange rate. During each experiment, an experienced smoker followed an identical puffing protocol on one of four different methods of consuming marijuana: the pre-rolled marijuana joint (24 experiments), the bong with its bowl containing marijuana buds (9 experiments), the glass pipe containing marijuana buds (9 experiments), and the commercially available electronic vaping pen with a cartridge attached containing cannabis vape liquid (9 experiments). For comparison, we used the same puffing protocol to measure the PM 2.5 emissions from Marlboro cigarettes (9 experiments). The results indicated that cannabis joints produced the highest indoor PM 2.5 concentrations and had the largest emission rates, compared with the other cannabis sources. The average PM 2.5 emission rate of the 24 cannabis joints (7.8 mg/min) was 3.5 times the average emission rate of the Marlboro cigarettes (2.2 mg/min). The average emission rate of the cannabis bong was 67% that of the joint; the glass pipe's emission rate was 54% that of the joint, and the vaping pen's emission rate was 44% that of the joint. The differences compared to the joint were statistically significant. • 60 experiments comparing indoor PM 2.5 from secondhand marijuana & tobacco smoke. • The marijuana joint's emission rate was 3.5 times that of the tobacco cigarette. • All the cannabis sources had PM 2.5 emission rates greater than tobacco cigarettes. • The order of cannabis emission rates was joint, bong, glass pipe, and vaping pen. • The vaping pen's mean decay rate exceeded the other sources' mean decay rates.

Ambient Atmospheric Aerosol Extinction Coefficient Reconstruction from PM2.5 Mass Concentrations and Application to Haze Identification in China

ABSTRACT This study developed a method of reconstructing the aerosol extinction coefficient based on hourly observations of the fine-particle (PM2.5) mass concentration, relative humidity (RH), and visibility at 9 stations in China between 2014 and 2015. First, we applied κ-Kӧhler theory to evaluate the number concentration distribution of the fine particles under ambient conditions from the PM2.5 mass and then used Mie theory to calculate the aerosol extinction coefficient. Second, we established the reconstruction model and identified reference values for the relevant parameters. After sensitivity tests confirmed good agreement between the extinction coefficients obtained through combinations of various values and those resulting from the reference values, linear regression was employed to reduce the discrepancy between the reconstructed and the observed coefficients. A closure study enabled us to determine the threshold of the extinction ratio (β/βObs) and identify haze and fog weather phenomena at the stations. Finally, we assessed the bias in the predicted number of hours with haze for 61 stations in China by comparing the estimates derived from different values for the model’s parameters with those derived from the reference values and found a relative bias of less than 15% for approximately 99.8% of the stations, indicating the feasibility of our approach for detecting haze.

Dispersion Characteristics of PM10 Particles Identified by Numerical Simulation in the Vicinity of Roads Passing through Various Types of Urban Areas

The dispersion of particulate matter emitted by road transport to the vicinity of roads is predominantly influenced by the character of the air velocity field. The air flow depends on factors such as the speed and direction of the blowing wind, the movement of cars, and the geometries of the buildings around a road. Numerical modeling based on the control volume method was used in this study to describe the relevant processes closely. Detailed air velocity fields were identified in the vicinity of a straight road surrounded by various patterns of built-up urban land. The evaluation of the results was generalized to exponential expressions, affecting the decrease of the mass concentration of fine particles with the increasing distance from the road. The obtained characteristics of the mass concentration fields express the impact of the building geometries and configurations on the dispersion of particulate matter into the environment. These characteristics are presented for two wind speeds, namely, 2 m·s−1 and 4 m·s−1. Furthermore, the characteristics are introduced in relation to three wind directions: perpendicularly, obliquely, and in parallel to the road. The results of the numerical simulations are compared with those obtained via the in-situ measurements, for verification of the validity of the linear emission source calculation.

Seasonal and long-term trends of sulfate, nitrate, and ammonium in PM2.5 in Beijing: implication for air pollution control.

Particulate matter pollution in Beijing is a serious environmental problem. In response to this, the Beijing government has implemented comprehensive emission reduction measures in recent years. To assess the effectiveness of these measures, the seasonal and long-term trends in chemical compositions of PM2.5 in Beijing have been studied based on daily samples collected from July 2015 to April 2016 and literature investigation (2000-2014). Results show that the concentrations of sulfate, nitrate, and ammonium in PM2.5 have significant seasonal variations, which are related to the changes in meteorological conditions and emission intensities. In addition, the long-term data display that the concentrations of sulfate, nitrate, and ammonium have significantly decreased between 2013 and 2016, which are consistent with the reduction in PM2.5 levels (~ 11.2μg/m3 per year). The declines could not be interpreted by the meteorological factors. It suggests that the air pollution control measures in Beijing (2013-2016), especially the decreasing consumption of coal, can effectively decrease the mass concentration of fine particles. To further improve the air quality, similar measures should be adopted in the areas around Beijing. These air pollution control measures taken in Beijing can provide invaluable guidance for mega-cities in China and other developing countries to decrease their PM2.5 concentration and reduce health risk from particulate pollution.

Winter Urban Chemistry and Denver’s Brown Cloud: Part 1—Light Extinction and Visibility

An example of winter visibility impairment from air pollution has been observed over Denver, Colorado (USA) from studies of the sources and characteristics of the haze conducted since the 1960s. A 1978 keystone study of this phenomenon provides the basis for many subsequent experimental designs. The 1978 results show how the coupling of short duration measurements of meteorological processes and air chemistry, combined with source data, yield key information about urban haze. The study employed six stations, with measurements including diurnal particle concentrations and optical properties. The results affirmed the association between the mass concentration of fine particles and light extinction. Extinction in the haze depended mainly on particles containing carbon, sulfate, and nitrate, with contributions from dust and NO2 absorption. Diurnal data show the spatio-temporal variability of mass concentration and light extinction across the city, which are related to sources and meteorology. The composition of fine particles is used with receptor modeling for source apportionment of extinction. Results from this and later studies are relevant to current conditions not only in Denver, but also cities across North America and Asia, and demonstrate that “newly discovered” relationships between visibility and particulate matter were evident more than 4 decades ago.

Promoting the removal of fine particles and zero discharge of desulfurization wastewater by spray-turbulent agglomeration

The treatment of fine particles and desulfurization wastewater from coal-fired power plants is an important issue in the field of energy and environment. To promote the removal of fine particles and zero discharge of desulfurization wastewater, a novel treatment technology with the coupling of spray evaporation and turbulent agglomeration was proposed, and the effect of desulfurization wastewater spray on fine particles agglomeration and removal were investigated by experiment. The results showed that the spray-turbulent agglomeration system can effectively promote the agglomeration and removal of fine particles through capillary force and adhesion effect of crystals precipitated from the desulfurization wastewater droplets. After that the fine particles agglomeration efficiency was improved to 39.3%, which was 10.9% higher than single turbulent agglomeration, and the number and mass concentrations of fine particles after ESP reduced about 46.5% and 38.9%, respectively. In addition, the effect of turbulent agglomeration system on the evaporation of desulfurization wastewater was studied by simulation using CFD models, the motion trajectory, evaporation time and motion distance of spray droplets with different sizes were calculated. It indicated that turbulence can increase the relative velocity between droplets and flue gas, thus improving the heat and mass transfer rates of spray droplets in the evaporation process, so as to promote the evaporation of large-size droplets and shorten their motion distance required for complete evaporation. The average motion distance of spray droplets was shortened by 383 and 543 mm respectively at the diameter size of 110 and 120 μm.

Indoor and Outdoor Concentrations of Particulate Matter in an Airport Terminal Building: A Pilot Study at Soekarno-Hatta International Airport in Indonesia

The air quality inside airport terminal buildings is a lesser studied area compared to ambient air quality at the airport. The contribution of outdoor particulate matter (PM), aircraft traffic, and passenger traffic to indoor PM concentration is not well understood. Using the largest airport in Southeast Asia as the study site (extends 17.9 square kilometers), the objective of this paper is to conduct a preliminary analysis to examine the mass concentrations of fine particles, including PM1 and PM2.5, and coarse particles PM2.5–10 inside a four-story terminal building spanning 400,000 square meters in Jakarta, Indonesia. The results showed the indoor/outdoor (I/O) ratio of 0.42 for PM1 with 15-min time lag and 0.33 for PM2.5 with 30-min time lag. The aircraft traffic appeared to have a significant impact on indoor PM1 and PM2.5, whereas the passenger traffic showed an influence on indoor PM2.5–10.

Within-city Spatial Variations in Ambient Ultrafine Particle Concentrations and Incident Brain Tumors in Adults.

Ambient ultrafine particles (UFPs, <0.1 µm) can reach the human brain, but to our knowledge, epidemiologic studies have yet to evaluate the relation between UFPs and incident brain tumors. We conducted a cohort study of within-city spatial variations in ambient UFPs across Montreal and Toronto, Canada, among 1.9 million adults included in multiple cycles of the Canadian Census Health and Environment Cohorts (1991, 1996, 2001, and 2006). UFP exposures (3-year moving averages) were assigned to residential locations using land-use regression models with exposures updated to account for residential mobility within and between cities. We followed cohort members for malignant brain tumors (ICD-10 codes C71.0-C71.9) between 2001 and 2016; Cox proportional hazards models (stratified by age, sex, immigration status, and census cycle) were used to estimate hazard ratios (HRs) adjusting for fine particle mass concentrations (PM2.5), nitrogen dioxide (NO2), and various sociodemographic factors. In total, we identified 1,400 incident brain tumors during the follow-up period. Each 10,000/cm increase in UFPs was positively associated with brain tumor incidence (HR = 1.112, 95% CI = 1.042, 1.188) after adjusting for PM2.5, NO2, and sociodemographic factors. Applying an indirect adjustment for cigarette smoking and body mass index strengthened this relation (HR = 1.133, 95% CI = 1.032, 1.245). PM2.5 and NO2 were not associated with an increased incidence of brain tumors. Ambient UFPs may represent a previously unrecognized risk factor for incident brain tumors in adults. Future studies should aim to replicate these results given the high prevalence of UFP exposures in urban areas.

Mass concentration and size distribution of particles released from harvesting and biomass burning of sugarcane

AbstractWe evaluated size distribution and mass concentrations of fine (particulate matter &lt; 2.5 μm, PM2.5) and coarse (particulate matter = 2.5–10 μm, PM2.5‐10) particles released during sugarcane (Saccharum spp.) harvesting operations, including cutting of green cane (GH), burning of standing cane (SB), cane harvest cutting after SB (BH), and ground burning of harvest residues left in the field (GB). Total number of PM2.5 released from GB was 1.63 times greater than that from SB. Total time of burning (flaming + smoldering) phase during GB was 1.5 to 2.1 times longer than SB. The flaming phase for both GB and SB was shorter than the smoldering phase but emitted 5.2 to 7.5 times more PM2.5. Average particle density of PM2.5 from burning operations was 1.12 g cm−3 for GB and 0.52 g cm−3 for SB. The GH and BH released lower PM2.5 but higher PM2.5‐10 as compared to SB and GB. Overall, biomass burning, regardless GB and SB difference, released significantly higher PM2.5 than harvest‐cutting operations.

Fine Particle Emissions from Sauna Stoves: Effects of Combustion Appliance and Fuel, and Implications for the Finnish Emission Inventory

Sauna Stoves (SS) are simple wood combustion appliances used mainly in Nordic countries. They generate emissions that have an impact on air quality and climate. In this study, a new measurement concept for comparing the operation, thermal efficiency, and real-life fine particle and gaseous emissions of SS was utilized. In addition, a novel, simple, and universal emission calculation procedure for the determination of nominal emission factors was developed for which the equations are presented for the first time. Fine particle and gaseous concentrations from 10 different types of SS were investigated. It was found that each SS model was an individual in relation to stove performance: stove heating time, air-to-fuel ratio, thermal efficiency, and emissions. Nine-fold differences in fine particle mass (PM1) concentrations, and about 90-fold differences in concentrations of polycyclic aromatic hydrocarbons (PAH) were found between the SS, when dry (11% moisture content) birch wood was used. By using moist (18%) wood, particle number and carbon monoxide concentrations increased, but interestingly, PM1, PAH, and black carbon (BC) concentrations clearly decreased, when comparing to dry wood. E.g., PAH concentrations were 5.5–9.6 times higher with dry wood than with moist wood. Between wood species, 2–3-fold maximum differences in the emissions were found, whereas about 1.5-fold differences were observed between bark-containing and debarked wood logs. On average, the emissions measured in this study were considerably lower than in previous studies and emission inventories. This suggests that overall the designs of sauna stoves available on the market have improved during the 2010s. The findings of this study were used to update the calculation scheme behind the inventories, causing the estimates for total PM emissions from SS in Finland to decrease. However, wood-fired sauna stoves are still estimated to be the highest individual emission source of fine particles and black carbon in Finland.

Characteristics of Haze Pollution Episodes During Autumn and Winter in 2018 in Shijiazhuang

The mass concentration and chemical composition of fine particles were continuously observed on-line from October 31 to December 3, 2018 at Hebei Key Laboratory of Haze Pollution Prevention and Control in Shijiazhuang. The characteristics of haze pollution in autumn and winter in Shijiazhuang were analyzed. The results showed that during the observation period, four haze pollution episodes occurred with PM2.5 as the primary pollutant, and the maximum daily concentration was 154, 228, 379, and 223 μg·m-3, respectively, reaching a heavy pollution level or above. The main components of PM2.5were water-soluble inorganic ions (WSⅡ) and carbon-containing aerosols, accounting for (60.7±15.6)% and (21.6±9.7)% of PM2.5 mass concentration, respectively. Compared with clean days, the mass concentration of WSⅡ and carbon aerosol during haze pollution increased by 4.4 times and 3.1 times, respectively, which was the main cause of haze pollution. NO3-, SO42-, and NH4+(SNA) were the main components of WSⅡ, accounting for (91.5±17.3)% of the total WSⅡ concentration, of which NO3- took up the highest proportion. The explosive growth of SNA during haze pollution was the main reason for the extremely high PM2.5concentration. Under non-high humidity conditions, the formation rates of unit mass substrates (NO3-, SO42-) were not significantly different, but the transformation of SO42- was significantly promoted after the liquid phase oxidation of SO2 was triggered under high humidity conditions. The atmosphere in Shijiazhuang is rich in NH3, and the molar ratio of n(NH4+) to n(NO3-+2×SO42-) in PM2.5 was greater than 1. The presence of a large amount of NH3 could promote the transformation of NO3- and SO42- and aggravate pollution. During the haze pollution period, the accumulation of primary pollutants from coal and motor vehicles was the main reason for the increase in carbon-containing aerosol. Compared with clean days, the formation of SOC was inhibited. Before the beginning of the warm season, the mobile form was the main pollution source of PM2.5, contributing 30.8% and 39.8% of PM2.5 mass concentration. With the increase of coal combustion emissions, the contribution of coal-fired sources gradually increased to 25.5%, becoming the primary pollution source.

Fine and Coarse Particle Concentration and Composition Measured In Urban And Non Urban Area Bandung, West Java - Indonesia

Atmospheric particulate concentrations for fine (particulate matter less than 2.5 micron) and coarse particles (particle with diameter 2.5-10 micron) were measured in 2 locations which are Tegalega and Dago Pakar Bandung. Tegalega represents an urban mixed site while Dago Pakar represents rural site. Samples on each location were collected over one or two days-time periods during dry and wet season using Dichotomous sampler and Low Volume Sampler (LVS). Meteorological conditions were also measured simultaneously in the sampling locations. Samples were further analyzed to determine concentrations of particulate mass, elements, sulfate, nitrate and ammonium. The results from this study show that the concentrations of the particulate mass were higher during the dry season than in the wet season for both locations, mixed and background sites. The average fine particles concentrations at mixed site were 37 and 49 μg/m3 for the wet and dry seasons respectively. The average coarse particles concentrations were 27 and 33 μg/m3 for wet and dry seasons respectively. The average mass concentrations of fine particles at the rural site were 30 and 45 μg/m3 for wet and dry seasons respectively, while for the coarse particles the concentrations were 13 for wet season and 17 μg/m3 in dry season. Concentration of Black Carbon, sulfate, nitrate, and ammonium mostly existed in the fine fraction while crustal elements dominated the coarse fraction. Black Carbon, Sulfate, nitrate and ammonium contributed about 55 % to the total mass of the fine particles at Mixed site (Tegalega) and about 52 % at rural site (Dago Pakar) in dry season. Fine particulate contribute about 57 % to the PM10 in Tegalega and about 73% in Dago Pakar (rural site). This indicates that fine particles may come from other places (transported) in the rural area.

Ultrafine, fine and coarse airborne particle mass concentration in workplaces

As epidemiological studies have shown a significant association between exposure to particles and mortality and morbidity, depending on their different deposition efficiency in the pulmonary region, size-segregated particulate matter (PM) samples were collected in workplaces where high PM concentrations were expected and compared with the results from urban and background atmospheres.We investigated the following workplaces: an analytical chemistry laboratory, a wastewater treatment plant, a livestock farming activity, a municipal solid waste composting plant, and a waste electrical and electronic equipment (WEEE) Treatment Facility. The highest PM concentrations were found in the last three sites.Ultrafine PM (PM0.1: aerodynamic diameter less than 0.1 μm) mass concentrations also proved to be especially high in the livestock farming activity, in the municipal solid waste composting plant, and in the WEEE treatment facility, ranging between 4.7 and 19.8 μg m−3 as mean values, suggesting that this particulate fraction should be monitored and controlled. On the other hand, in both natural and urban environments, ultrafine particles occurred at concentrations 0.1–0.3 times the workplace values. It would have been interesting to determine the increase in cancer risk due to ultrafine particles, but cohort studies on PM0.1 are lacking. Therefore, effects on the workers were investigated starting from the lifetime average daily PM2.5 dose. Even with this limitation, the results show that people working in municipal solid waste composting plant and in a WEEE Treatment Facility are exposed to a not negligible additional lifetime risk on respect citizens.

Impacts of relative humidity on fine aerosol properties via environmental wind tunnel experiments

This study used a closed-circuit boundary-layer wind tunnel, with a series of instruments including SO2, NO2, O3, NH3, and PM2.5 monitors and an Aerodyne Aerosol Mass Spectrometer (AMS), to explore the effects of relative humidity (RH) on properties of ambient fine particles (PM2.5 and PM1) in the northern suburbs of Nanjing. The results showed under all conditions the PM1 concentration were influenced largely by organic matter, and meanwhile, the contribution of sulfate decreased. Under non-humidification conditions, the mass concentrations of fine particles increased with the increase of RH. The mass concentration of PM2.5 was not influenced by the SO2 concentration and changed in a manner similar to those of the NO2 and NH3 concentrations at higher RH; however, the mass concentration varied inversely with changes of O3 concentration. The mass concentration and mass fraction of sulfate and nitrate changed in different manners as RH varied. CxHy+ ions took up the highest percentage of organic matter in the AMS spectra, indicating organics in a large part might be emitted as primary organic aerosol (POA), and the fine particles were overall alkaline. With atomized humidification (at constant temperature), the mass concentrations of all fine particles showed an explosive increase, with PM2.5 levels rising at an average rate of 11.9 μg/m3·min. The increase in the fine particle concentration was primarily due to increases in the PM1-2.5 level. The percentage of organic matter increased with RH, with CxHyO+ and CxHyOz+ ions becoming the major ion groups indicating the dominance of secondary organic aerosol (SOA) species, facilitated by high humidity. The SO42−/SO2 ratio increased with RH, indicating that sulfate was formed at high humidity rapidly via an aqueous-phase oxidation of SO2 and results show that O3 might become an important oxidant. The fine particles were acidic, and the increased O/C ratio also indicates the SOA contribution.

Dust emission from crushing of hard rock aggregates

Dust constitutes one of the major environmental concerns near many aggregate quarries, with crushing often being the most significant source. In this study, dust emissions and dispersion measurements were conducted under real operating conditions at six aggregate quarries in southern Finland. Five of them represent granitic rocks and one a limestone quarry.Dust concentrations during crushing were measured at varying distances with time intervals of five seconds. The variation in dust concentration was high within all the measured distances, ranging from 10 to 200 m.Crushing produces mainly coarse (TSP and PM10) dust particles, which settle near the dust source. The mass concentration of coarse particles in this investigation varied from few tens of μg/m3 to over 6.5 × 103 μg/m3 downwind from the crusher.The mass concentration of fine particles (PM2.5 and PM1) ranged between ten μg/m3 and few hundreds of μg/m3 downwind from the crusher. The fine particles originated mainly from machinery used in the quarries and remote sources, such as nearby traffic.In quarries operating with secondary crushing, the background concentrations were achieved approximately from a 350 m distance for coarse particles. Local dust sources, such as hauling, impacted the results inside the quarry. Crushing produced more dust compared to comparable studies for drilling. The dust concentrations at the limestone quarry were approximately 50% of concentrations measured at quarries with granitic rocks.

Oxidative potential of fine ambient particles in various environments

The oxidative potential (OP) and chemical characteristics of fine particles collected from urban, roadside, rural, and industrial sites in Korea during spring, summer, fall, and winter seasons and an urban site in the Philippines during dry and wet seasons were examined. Significant differences in the OP of fine particles among sites and seasons were found. The industrial site yielded the highest OP activity (both mass and volume-normalized OP) among the sites, suggesting the strongest reactive oxygen species (ROS)-generating capability of industry source-dominant PM2.5. Seasonal data show that OP activities increased during the spring and summer possibly due to increased heavy metals caused by dust events and secondary organic aerosols formed by strong photochemical activity, respectively. The strength of the OP association with the chemical components highlights the influence of organic carbon and transition metals on the OP of ambient fine particles. The two OP assays (dithiothreitol (DTT) and electron spin resonance (ESR)) having different ROS-generating mechanisms were found to have different sensitivities to the chemical components facilitating a complementary analysis of the OP of ambient fine particles. Multiple linear regression model equations (OP as a function of chemical components) which were dependent on the sites were derived. A comparison of the daily OP and hazard index (HI) (the ratio of the measured mass concentration to the reference mass concentration of fine particles) suggests that the HI may not be sufficient to accurately estimate the health effects of fine particles, and a direct or indirect measurement of toxicity such as OP should be required in addition to the concentration level.