Metals In Particulate Matter Research Articles

Heavy metals in industrially emitted particulate matter in Ile-Ife, Nigeria

Iron and steel smelting facilities generate large quantities of airborne particulate matter (PM) through their various activities and production processes. The resulting PM that contains a variety of heavy metals has potentially detrimental impacts on human health and the environment. This study was conducted to assess the potential health effects of the pollution from the heavy metals in the airborne PM sampled in the vicinity of secondary smelting operations in Ile-Ife, Nigeria. X-ray fluorescence (XRF) was used to determine the elemental concentration of Pb, Cr, Cd, Zn, Mn, As, Fe, Cu, and Ni in the size-segregated PM samples. Pollution Indices (PI) consisting of Contamination Factor (CF), Degree of Contamination (DC) and Pollution Index Load (PLI) and Target Hazard Quotient (THQ) were employed to assess the pollution risk associated with the heavy metals in the PM. CF, DC and PLI values were 3< CF <6, >32 and >1, respectively for the three sites, indicating deterioration of the ambient air quality in the vicinity of the smelter. The heavy metals in the airborne PM pose a severe health risk to people living in vicinity of the facility and to its workers. The diminished air quality with the associated health risks directly depends on the industrial emissions from steel production and control measures are recommended to mitigate the likely risks.

Equilibrium study of copper absorption to different types of soft contact lens

To measure binding affinity of copper, one of the heavy metals in particulate matter (PM) was applied to soft contact lenses made of two different materials because contact lenses are readily exposed to PM. Copper binding to ionized silicon hydrogel lens yielded an equilibrium association constant K a,eq value of 14.03 μM without color change of lens, compared to that of 19.16 μM for copper binding to de-ionized hydrogel lenses with color change of lens. The results indicated that the color change of lens is not consistent with the concentration of cooper deposition on lens, and copper bound relatively stronger in ionized silicon hydrogel lens than in de-ionized hydrogel lens. Therefore, the continuous exposure of contact lenses to high PM levels might lead to heavy metal deposition on the lens, which would be detrimental to ocular health.

Highly Acidic Ambient Particles, Soluble Metals, and Oxidative Potential: A Link between Sulfate and Aerosol Toxicity.

Soluble transition metals in particulate matter (PM) can generate reactive oxygen species in vivo by redox cycling, leading to oxidative stress and adverse health effects. Most metals, such as those from roadway traffic, are emitted in an insoluble form, but must be soluble for redox cycling. Here we present the mechanism of metals dissolution by highly acidic sulfate aerosol and the effect on particle oxidative potential (OP) through analysis of size distributions. Size-segregated ambient PM were collected from a road-side and representative urban site in Atlanta, GA. Elemental and organic carbon, ions, total and water-soluble metals, and water-soluble OP were measured. Particle pH was determined with a thermodynamic model using measured ionic species. Sulfate was spatially uniform and found mainly in the fine mode, whereas total metals and mineral dust cations were highest at the road-side site and in the coarse mode, resulting in a fine mode pH < 2 and near neutral coarse mode. Soluble metals and OP peaked at the intersection of these modes demonstrating that sulfate plays a key role in producing highly acidic fine aerosols capable of dissolving primary transition metals that contribute to aerosol OP. Sulfate-driven metals dissolution may account for sulfate-health associations reported in past studies.

Analysis of Aerosol Composition and Assessment of Tunnel Washing Performance within a Mass Rapid Transit System in Taiwan

ABSTRACTThe metro system is the main mode of transportation in Taipei City. The air quality of metro stations is crucial for passengers. This study investigated particle size distribution and its elemental composition and assessed tunnel washing performance in the Taipei Rapid Transit System (TRTS). A 24-hour particle sampling process was performed in the tunnels, platforms, and entrances and exits to measure particulate matter (PM)2.5 and PM10 concentrations in an underground metro station and to analyze PM metal components. PM10 and PM2.5 concentrations decreased sequentially from the tunnels to the platforms and then to the entrances and exits to ambient environment in the metro station. The main metal components of suspended particulates in the TRTS mainly included iron, barium, copper, manganese, magnesium, aluminum, chromium, zinc, nickel, and lead. The total PM10 and PM2.5 metal proportions were 33.9%–24.7% and 32.9%–22.8%, respectively. Furthermore, the effectiveness of tunnel washing in reducing the PM concentration was investigated. Monitoring results showed an increase in PM10 and PM2.5 concentrations after tunnel washing on the first day. The PM concentration started to decrease from the second day. Furthermore, 3.5 months after tunnel washing, the PM10 concentration decreased by 45.9%, and 2 months after tunnel washing, the PM2.5 concentration decreased by 71.3%. The mechanism of the continuous reduction in the PM10 concentration after cleaning is probably related to the porous material of tunnel walls, which may provide a deposition sink for aerosol particles, as well as the filter effect of the air conditioning system. This is the first study to use full-section tunnel washing to reduce PM exposure at mass rapid transit (MRT) stations. Although full-section tunnel washing reduced the PM concentration in the metro station, accessorial technology, such as the air conditioning system or platform design, may help in reducing the exposure of MRT passengers.

Temporal variation and trace metal characterisation of particulate matter in ambient air of rural and urban areas of lucknow, India

Temporal variation in the concentration of particulate matter (PM) was monitored at an institutional and rural area of Lucknow. The concentration of coarse (PM10) and fine particulates (PM2.5) was found to be in the range of 134.14–387.64 (225.79±76.34), 108.47–233.38 (147.15±36.47) and 90.68–220.8 (136.19±37.08), 33.13–113.67 (83.47±24.73) μg/m3 at institutional and rural area, respectively. Average PM10 and PM2.5 concentration at both the locations were found to be beyond the permissible limits, that is 100, 60 μg/m3(National Ambient Air Quality Standards) and 150, 35 μg/m3 of (United State Environmental Protection Agency) for institutional and rural areas, respectively. Average PM2.5-to-PM10 ratio was found to be. 63±.11;. 57±.15 at institutional and rural area, respectively, which indicates the higher contribution of fine particulates in PM10. Further, the PM10 was subjected for trace metal characterisation in terms of Fe, Pb, Zn, Cd and Cu. Trace metal concentration (ng/m3) associated with PM10 at both the locations was found to be in the order of Fe (823.87) > Pb (198.67) > Zn (93.19) > Cd (88.10) > Cu (37.60). The Pearson correlation of trace metals associated with PM10 and meteorology showed significant correlation at P<.05 and P<.01 levels; which inferred that the PM and trace metals were originated from similar sources.

Chemical fractionation and health risk assessment of particulate matter-bound metals in Pune, India.

The present study deals with the assessment of sequential extraction of particulate matter (PM)-bound metals and the potential health risks associated with them in a growing metropolitan city (Pune) of India. The average mass concentration of both PM2.5-10 and PM2.5 exceeded the National Ambient Air Quality Standards. Significant seasonal variation in mass concentration was found for both size fractions of PM with higher values in winter season and lower in monsoon. Chemical species of the studied trace metals in PM exhibited significant differences, due to difference in sources of pollution. Metals such as Cd, Pb, and Cr in both size fractions and Zn and Co in fine fraction were more efficiently extracted in mobile fractions showing their mobile nature while Ni and Fe showed reduced mobility. Fe showed the highest concentrations among all the analyzed elements in both coarse (PM2.5-10) and fine (PM2.5) PM, while Cd showed least concentration in both size fractions. PCA identified industrial emissions, vehicular activity, coal combustion, diesel exhaust, waste incineration, electronic waste processing, constructional activities, soil, and road dust as probable contributors responsible for the metallic fraction of PM. All the metals showed varying contamination in PM samples. The contamination was higher for fine particles than coarse ones. The average global contamination factor was found to be 27.0-34.3 in coarse and fine PM, respectively. The hazard quotient (HQ) estimated for Cd, Co, and Ni (both total and easily accessible concentrations) exceeded the safe level (HQ=1), indicating that these metals would result in non-carcinogenic health effects to the exposed population. The HQ ranged from 9.1×10-5 for Cu (coarse) to 8.3 for Ni (fine) PM. The cancer risk for Cd, Ni, and Cr in both sized PM were much higher than the acceptable limits of USEPA.

Airborne foliar transfer of PM bound heavy metals in Cassia siamea: A less common route of heavy metal accumulation

In order to investigate possible foliar transfer of toxic heavy metals, concentrations of Cd, Pb, and Fe were measured in samples of: Cassia siamea leaves (a common tree) Cassia siamea foliar dust, nearby road dust, and soil (Cassia siamea tree roots) at six different sites in/around the Bilaspur industrial area and a control site on the university campus. Bilaspur is located in a subtropical central Indian region. The enrichment factor (EF) values of Pb and Cd, when derived using the crustal and measured soil Fe data as reference, indicated significant anthropogenic contributions to Pb and Cd regional pollution. Based on correlation analysis and scanning electron microscopy (SEM) observations, it was evident that Pb and Cd in foliar part of Cassia siamea were largely from airborne sources. The SEM studies of leaf confirmed that leaf morphology (epidermis, trichome, and stomata) of Cassia siamea helped accumulate the toxic metals from deposited particulate matter (PM). There is a line of evidence that the leaf of Cassia siamea was able to entrap PM in respirable suspended particulate matter (RSPM) range (i.e., both in fine and coarse fractions). The overall results of this study suggest that Cassia siamea can be a potential plant species to control the pollution of PM and PM-bound metals (Pb and Cd) in affected areas.

Association between personal exposure to metals in fine particulate matter and urinary metals: baseline results from a panel study

To investigate the associations between 21 metals in fine particulate matter (PM2.5) and their corresponding concentrations in urine in the general population. Between April and May 2011, this panel study enrolled 120 residents using random sampling approach in Wuhan communities which contained 3 035 subjects. Participants were aged 18 to 80 years and had lived in the sampling buildings for at least 5 years. Data from basic questionnaires, physical examinations, and morning blood and urine samples under fasting conditions were collected. Participants with missing data were excluded. Finally, 83 particpants included. Participants were instructed to use personal air samplers to continuously monitor PM2.5 for 24 h. The following 21 metals were measured in PM2.5 and urine by inductively coupled plasma mass spectrometry: aluminum, titanium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, rubidium, strontium, molybdenum, cadmium, tin, antimony, barium, tungsten, thallium and lead. The associations between PM2.5 metals and urinary metals were investigated using generalized linear regression models. The age of the study population was (51.5±6.3)years. After adjusting for age, sex, smoking status, BMI, education and income, elevated urinary chromium was significantly associated with increased chromium concentrations in personal PM2.5. The least square means (standard deviation) of urinary chromium in participants classified as having low exposure (<12.491 ng/m(3)), intermediate exposure (12.491-32.388 ng/m(3)) and high exposure (>32.388 ng/m(3)) were (-1.334±0.756), (-1.114±0.813) and (-0.718±0.645) μg/mmol creatinine, respectively (P=0.009). However, the association between urinary and personal PM chromium was not observed after additionally adjusting for false discovery rate (P>0.05). Furthermore, the results demonstrated that other metals in PM2.5 were not related to their corresponding concentrations in urine of subjects. Urinary concentrations of metals did not reflect human exposure to metals in air, and may not be appropriate as an index to assess personal exposure to metals in particulate matter.

Trace metal content in inhalable particulate matter (PM2.5-10 and PM2.5) collected from historical mine waste deposits using a laboratory-based approach.

Mine wastes and tailings are considered hazardous to human health because of their potential to generate large quantities of highly toxic emissions of particulate matter (PM). Human exposure to As and other trace metals in PM may occur via inhalation of airborne particulates or through ingestion of contaminated dust. This study describes a laboratory-based method for extracting PM2.5-10 (coarse) and PM2.5 (fine) particles from As-rich mine waste samples collected from an historical gold mining region in regional, Victoria, Australia. We also report on the trace metal and metalloid content of the coarse and fine fraction, with an emphasis on As as an element of potential concern. Laser diffraction analysis showed that the proportions of coarse and fine particles in the bulk samples ranged between 3.4-26.6 and 0.6-7.6%, respectively. Arsenic concentrations were greater in the fine fraction (1680-26,100mgkg-1) compared with the coarse fraction (1210-22,000mgkg-1), and Co, Fe, Mn, Ni, Sb and Zn were found to be present in the fine fraction at levels around twice those occurring in the coarse. These results are of particular concern given that fine particles can accumulate in the human respiratory system. Our study demonstrates that mine wastes may be an important source of metal-enriched PM for mining communities.

Mass size distribution and source identification of particulate matter metal components at four urban sites and a background site of Istanbul.

In this study, the size distribution characteristics and metal contents of particulate matter (PM) have been determined. In this scope, PM sampling has been done at five stations in Istanbul. PM filter samples were collected for eight different sizes using the Anderson cascade impactor. PM filters were decomposed and analyzed for 20 metals. The highest median concentration for Fe, Ca, K, and Mg, known as soil metals, were observed as follows: Fe and Ca were observed at Goztepe station (1.20 and 8.28μg/m(3)), K was observed at Kilyos station (0.33μg/m(3)), and Mg was observed at Avcilar station (0.37μg/m(3)). The highest median concentrations for Zn, Cu, Pb, Ni, Cr, V, As, Se, Co, and Cd, known as anthropogenic metals, were observed at Avcilar, Goztepe, and Besiktas stations. Although the lowest metal concentrations was determined at Kilyos stations that was selected as the urban background. The enrichment factors (EFs) of most metals in the fine PM is higher than those in the coarse mode. According to the factor analyses, the most important emission source was observed to be industrial facilities at Avcilar; traffic at Besiktas; traffic and domestic heating at Goztepe; and domestic heating, sea salt aerosols, and ship traffic (in the Bosphorus Channel of Istanbul) at Rasathane.

The effect of particulate matter on paper degradation

In this work we explore the chemical effects of particulate matter on paper. We exposed paper made of pure cellulose to the environment in different locations in central London, outdoors (in sheltered conditions) and indoors, for a period of up to 6 months. We monitored particulate matter (PM) deposition by counting the particles deposited every month with a scanning electron microscope. We analysed elemental composition of the deposited particles using inductively coupled plasma mass spectrometry. After accelerated degradation of the exposed samples, we determined the degree of polymerisation using viscometry. We observed higher deposition rates and higher metal concentration outdoors than indoors. Elemental analysis of the deposited particles revealed the presence of some transition metals (Fe, Cu, Cr) that can contribute to the degradation of cellulose fibres through the Fenton reaction. By comparing the degree of polymerisation of protected, unprotected and unexposed samples we could determine the relative contribution of PM deposition on the increase of the degradation rate. We found that the surface concentration of iron correlates with the reduction in the degree of polymerisation of the exposed paper. The results suggest that the presence of Fenton metals in PM has a significant effect on the acceleration of the degradation of cellulose. However, we estimate that this will unlikely occur at the levels of area coverage by PM that are typically avoided in indoor heritage through preventive maintenance and cleaning.

Seasonal Variation of Selected Metals in Particulate Matter at an Industrial City Kota, India

This study investigates seasonal variation in concentration of some heavy metals in suspended and respirable particulate matter (SPM and RPM) collected from five different zones situated in Kota city during both summer (March, April, May and October) and winter (January, February, November and December) seasons of 2011–2012. Mean concentrations of anthropogenic origin metals (Pb, Zn, Cu and Cd) were higher in winter and lower in summer with their relative abundance in order: Zn ＞ Pb ＞ Cu ＞ Cd while reverse trend was observed for crustal origin metals (Ca, Mg and Fe) at all zones. Meteorological conditions such as temperature, relative humidity, wind velocity and wind direction during winter and summer were found affecting the metals concentration trends in different seasons. Wind roses indicate that the zones lying in predominant North-east wind direction from point source (KSTPS) in winter (25.74%) and summer (15.31%) faced higher metal burden following zone 1, which is suffering most owing to its closest location to the source. Statistical analysis by Pearson’s correlations, enrichment factor and principal component analysis indicates that coal based Thermal Power Plant is the major source of heavy metals besides other industrial activities in the study area. It is to be noted that because of higher residence time, significant concentration of Pb is found at all the zones in the city which, probably, has its origin in earlier vehicular exhaust as well.

Between-strain differences in hypothermic response in mice after intranasal administration of PtO nanoparticles

Air pollution by particulate matter (PM) has been associated with cardiopulmonary morbidity and mortality in many recent epidemiological studies. It has been shown that transition metal compounds, well- known toxic components of PM, are able to induce hypothermia following whole-body inhalation exposure. Low temperature appears to protect tissue against toxic effects of PM metal compounds in vivo and in vitro. To study the role of soluble and insoluble irritants in the induction of the hypothermic response, we analyz­ed the decrease in mouse body temperature (Δtbody) after intranasal administration of PtO nanoparticles or a K2[PtCl 4] solution. Between-strain differences in Δtbody after intranasal administration of the irritants were evaluated using 6 inbred (BALB/cJ, C57BL/6J, AKR/OlaHsd, DBA/2JRccHsd, C3H/HeNHsd, and SJL/J) and 2 outbred mouse strains (SCID and CD1). BALB/cJ and SCID mice showed the most pronounced effect of intranasal admini­stration of the xenobiotic on tbody. Thus, tbody was signi­ficantly lower after nasal administration the PtO nano­particles than after administration of the K2[PtCl 4] solution. To study the mechanism of this decrease, we compar­ed the respective values for Δtbody following intra­nasal, intravenous and peroral administration of PtO nanoparticles in Balb/c mice. Neither intravenous nor peroral administration had any effect on mouse body temperature. This fact together with data on the dynamics of the decrease in mouse body temperature following intranasal administration of PtO nanoparticles (max Δtbody ~ 80–100 min) allowed us to assume that this process is under nervous regulation. The correlation found between our data and some well-known phenotypic characteristics (phenome.jax.org) of the mouse strains used confirms this hypothesis.

Impacts of co-firing biomass on emissions of particulate matter to the atmosphere

Gas and particle emissions from co-firing coal and two types of biomass versus coal was evaluated in a circulating fluidized bed boiler operating with a constant energy input. Compared to coal, co-firing 50% oat hulls (by weight) significantly reduced the emission of particulate matter (PM) by 90%, polycyclic aromatic hydrocarbons (PAH) by 40%, metals by 65%, and fossil carbon dioxide by 40%. In contrast, co-firing 3.8% wood chips (by weight) had a negligible impact on the emissions of PM and PAH, but caused a 6% reduction in metals. Fuel-based emission factors for PM, metals, and organic species including biomass burning markers retene and levoglucosan, were determined. Enrichment factors (EF) were computed to examine the distribution of metals across PM, fly ash, and bottom ash and demonstrated enrichment in volatile metals (e.g. Fe, Al, and Cr) in PM and fly ash. Co-firing 50% oat hulls led to a significant depletion of K in PM and its enrichment in bottom ash. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX) analysis revealed a wide heterogeneity in particle sizes and compositions across particles for all fuel types. Overall, this study demonstrates that co-firing a 50% oat hulls with coal provides several benefits to air quality and outlines important changes to PM composition when biomass is co-fired with coal.

Bioaccessibility of trace elements in fine and ultrafine atmospheric particles in an industrial environment

The lung bioaccessibility, i.e., the solubility in alveolar lung fluid of metals in particulate matter, has been recognized as an important parameter for health risk assessment, associated with the inhalation of airborne particles. The purpose of this study is to use an in vitro method to estimate the pulmonary bioaccessibility of toxic metals in different particle sizes, from a multi-influenced industrial emission area. The fine and ultrafine particles collected with cascade impactors in the chimneys and at different distances from a Fe-Mn smelter were extracted with a simulated alveolar fluid (Gamble solution). In addition, a four-step sequential extraction procedure was employed to approach the metal speciation. The bioaccessibility of metals ranged from almost insoluble for Fe (<1%) to extremely soluble for Rb (>80%). In terms of particle size, the trace element bioaccessibility is generally higher for the finer size fractions (submicron and ultrafine particles) than for the coarse one (>1 µm). These submicron particles have a very high number concentration and specific surface area, which confer them an important contact surface with the alveolar fluid, i.e., a higher bioaccessibility. Interestingly, the bioaccessibility of most metals clearly increases between the chimney stacks and the close environment of the studied Fe-Mn smelter, over a very short distance (800 m), possibly due to a mix with surrounding steelworks emissions. This increase is not observed over a greater distance from the smelter (2000 m), when industrial particles were mixed with urban aerosols, except for Fe, under more soluble forms in combustion particles.

Evaluation of a flue gas cleaning system of a circulating fluidized bed incineration power plant by the analysis of pollutant emissions

Air pollution caused by flue gas from municipal solid waste (MSW) incineration is becoming increasingly serious. There are many harmful products in flue gas, such as acid gases (SO2, NOx, and HCl, etc.), particulate matter (PM), heavy metals, and organic compounds. For controlling emission of toxic substances, the choice of the flue gas cleaning system plays an important role in the operation of an incinerator plant. In this study, a flue gas cleaning system of a power plant with circulating fluidized bed (CFB) incinerators of MSW located in Shandong Province (eastern China) was evaluated. The investigation included the removal of organic pollutants, PM, acid gases, and heavy metals. According to data of pollutants in the flue gas, the emission level of these items was under control and met the required domestic regulations. In order to comply with relevant international standards and the zero-release project, the selective non-catalytic reduction (SNCR), calcium magnesium acetate (ACM), catalytic filtration (CF), and secondary bag filter systems were suggested to optimize the existing flue gas cleaning system. The application of CFB incinerators with a semi-dry scrubber, activated carbon injection, and a bag filter to small and mid-sized cities in China serves as an example for developing countries in MSW management.

Cardiac effects of seasonal ambient particulate matter and ozone co-exposure in rats.

BackgroundThe potential for seasonal differences in the physicochemical characteristics of ambient particulate matter (PM) to modify interactive effects with gaseous pollutants has not been thoroughly examined. The purpose of this study was to compare cardiac responses in conscious hypertensive rats co-exposed to concentrated ambient particulates (CAPs) and ozone (O3) in Durham, NC during the summer and winter, and to analyze responses based on particle mass and chemistry.MethodsRats were exposed once for 4 hrs by whole-body inhalation to fine CAPs alone (target concentration: 150 μg/m3), O3 (0.2 ppm) alone, CAPs plus O3, or filtered air during summer 2011 and winter 2012. Telemetered electrocardiographic (ECG) data from implanted biosensors were analyzed for heart rate (HR), ECG parameters, heart rate variability (HRV), and spontaneous arrhythmia. The sensitivity to triggering of arrhythmia was measured in a separate cohort one day after exposure using intravenously administered aconitine. PM elemental composition and organic and elemental carbon fractions were analyzed by high-resolution inductively coupled plasma–mass spectrometry and thermo-optical pyrolytic vaporization, respectively. Particulate sources were inferred from elemental analysis using a chemical mass balance model.ResultsSeasonal differences in CAPs composition were most evident in particle mass concentrations (summer, 171 μg/m3; winter, 85 μg/m3), size (summer, 324 nm; winter, 125 nm), organic:elemental carbon ratios (summer, 16.6; winter, 9.7), and sulfate levels (summer, 49.1 μg/m3; winter, 16.8 μg/m3). Enrichment of metals in winter PM resulted in equivalent summer and winter metal exposure concentrations. Source apportionment analysis showed enrichment for anthropogenic and marine salt sources during winter exposures compared to summer exposures, although only 4% of the total PM mass was attributed to marine salt sources. Single pollutant cardiovascular effects with CAPs and O3 were present during both summer and winter exposures, with evidence for unique effects of co-exposures and associated changes in autonomic tone.ConclusionsThese findings provide evidence for a pronounced effect of season on PM mass, size, composition, and contributing sources, and exposure-induced cardiovascular responses. Although there was inconsistency in biological responses, some cardiovascular responses were evident only in the co-exposure group during both seasons despite variability in PM physicochemical composition. These findings suggest that a single ambient PM metric alone is not sufficient to predict potential for interactive health effects with other air pollutants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-015-0087-3) contains supplementary material, which is available to authorized users.

Characteristics of trace metals in traffic-derived particles in Hsuehshan Tunnel, Taiwan: size distribution, potential source, and fingerprinting metal ratio

Abstract. Traffic emissions are a significant source of airborne particulate matter (PM) in ambient environments. These emissions contain an abundance of toxic metals and thus pose adverse effects on human health. Size-fractionated aerosol samples were collected from May to September 2013 by using micro-orifice uniform deposited impactors (MOUDIs). Sample collection was conducted simultaneously at the inlet and outlet sites of Hsuehshan Tunnel in northern Taiwan, which is the second-longest freeway tunnel (12.9 km) in Asia. This endeavor aims to characterize the chemical constituents and size distributions, as well as fingerprinting ratios of particulate metals emitted by vehicle fleets. A total of 36 metals in size-resolved aerosols were determined through inductively coupled plasma mass spectrometry. Three major groups – namely, tailpipe emissions (Zn, Pb, and V in fine mode), wear debris (Cu, Cd, Fe, Ga, Mn, Mo, Sb, and Sn), and resuspended dust (Ca, Mg, K, and Rb) – of airborne PM metals were categorized on the basis of the results of enrichment factor, correlation matrix, and principal component analysis. Size distributions of wear-originated metals resembled the pattern of crustal elements, which were predominated by super-micron particulates (PM1–10). By contrast, tailpipe exhaust elements such as Zn, Pb, and V were distributed mainly in submicron particles. By employing Cu as a tracer of wear abrasion, several inter-metal ratios – including Fe / Cu (14), Ba / Cu (1.05), Sb / Cu (0.16), Sn / Cu (0.10), and Ga / Cu (0.03) – served as fingerprints for wear debris. However, the data set collected in this work is useful for further studies on traffic emission inventory and human health effects of traffic-related PM.

Human health risk assessment of airborne metals to a potentially exposed community: a screening exercise

Exposure to high concentrations of inhalable particulate matter (PM) is a known human health risk, depending on the chemical composition of the PM inhaled. Mogale City (Gauteng) is known for having several sources of airborne PM, however, less is known about the metals in the airborne PM. The aim of this study was to determine the metals in measured PM at Kagiso, Mogale City. An independent PM10 monitor was installed at the municipality’s existing monitoring site. This monitor continuously monitored PM10 between 23 August and 9 October 2013 and simultaneously sampled particles below 20 μm in diameter onto a glass fibre filter. This filter was replaced once towards the middle of the monitoring period. These two filters were chemically analysed to determine their metal content (30 metals) by the South African Bureau of Standards accredited laboratory at the Council for Scientific and Industrial Research by means of Inductively Coupled Plasma Spectroscopy (ICPS) based on the US EPA Method IO-3.1. To provide an estimate of possible health risk, the metal concentrations were used in a screening US-EPA human health risk assessment (HHRA). Since the analysed metals were reportedly below the detection limit, three hypothetical exposure scenarios (S) based on US-EPA recommendations were created for the HHRA. In S1, concentrations were considered to be the same as the detection limit for each metal; S2 assumed concentrations to be 50% of the detection limit; and S3 put concentrations at 10% of the detection limit. Potential risks (should pollution worsen) of developing respiratory and neurological effects were identified depending on the hypothetical scenarios. Continuous long-term monitoring and chemical characterisation are necessary to confirm these preliminary findings.

Microfluidic Devices for Aerosol Speciation and Personal Exposure Assessment in Panel-Based Epidemiology

A need exists to develop simple, low-cost methods for aerosol speciation and air quality measurement to support both medium-to-large-scale epidemiology and citizen-based science. Our group has developed alternative approaches for aerosol speciation using microfluidic technologies designed to manipulate teardrop sample volumes. Traditional and paper-based microfluidics are poised to overcome many issues associated with chemical analysis of particulate matter (PM), namely: cost, ease-of-use, and sensitivity. Results can be read using either the naked eye or simple, low-cost instrumentation (i.e., a handheld or mobile device). Such assays cost only a few dollars and can be conducted by virtually anyone after simple training. We have developed microfluidic assays to measure reactive oxygen species and metals (Fe, Ni, Cu, Cr, Pb, Cd) in PM using a combination of colorimetric and electrochemical detection motifs. Detection limits of 0.1?g were achieved for colorimetric assays (appropriate for occupational exposures) while electrochemical assays provided detection limits of 0.1 ng (1 ppb solution levels; appropriate for ambient PM). We have also validated these techniques against standard reference methods with relatively good agreement. To complement these analytic techniques, our group has also developed a series of low-weight, low-burden personal air samplers. These air samplers feature micropumps that provide silent operation and a leap in energy efficiency that allows significant minimization. Initial prototypes weigh less than 150g, emit virtually no noise, and are about the size of a box of crayons. Production costs for these air sampling pumps are targeted for &lt; $100, about ten times less than current competing technologies.