Size-fractionated Particulate Matter Research Articles

Methodological aspects of in vitro assessment of bio-accessible risk element pool in urban particulate matter.

In vitro tests simulating the elements release from inhaled urban particulate matter (PM) with artificial lung fluids (Gamble's and Hatch's solutions) and simulated gastric and pancreatic solutions were applied for an estimation of hazardous element (As, Cd, Cr, Hg, Mn, Ni, Pb and Zn) bio-accessibility in this material. An inductively coupled plasma optical emission spectrometry (ICP-OES) and an inductively coupled plasma mass spectrometry (ICP-MS) were employed for the element determination in extracted solutions. The effect of the extraction agent used, extraction time, sample-to-extractant ratio, sample particle size and/or individual element properties was evaluated. Different patterns of individual elements were observed, comparing Hatch's solution vs. simulated gastric and pancreatic solutions. For Hatch's solution, a decreasing sample-to-extractant ratio in a PM size fraction of <0.063mm resulted in increasing leached contents of all investigated elements. As already proved for other operationally defined extraction procedures, the extractable element portions are affected not only by their mobility in the particulate matter itself but also by the sample preparation procedure. Results of simulated in vitro tests can be applied for the reasonable estimation of bio-accessible element portions in the particulate matter as an alternative method, which, consequently, initiates further examinations including potential in vivo assessments.

Measuring ambient particulate matter in three cities in Cameroon, Africa

This is the first study of particulate matter (PM) air pollution in Cameroon. In this study, mass concentration and PM size fractions as well as carbonaceous contribution to PM are measured in Bafoussam, Bamenda, and Yaoundé, Cameroon. Average concentrations in Bafoussam, Bamenda, and Yaoundé of PM2.5 are 67 ± 14, 132 ± 64, and 49 ± 12 μg/m3 and PM10 are 105 ± 29, 141 ± 107, and 65 ± 21 μg/m3, respectively. Daytime levels of PM2.5 and PM10 are seen to be higher than nighttime levels in all cities except Bamenda where nighttime levels are higher for both PM sizes. In Bafoussam, the average PM1.0 particle number concentration during the day is 19,800 pt/cc and during the evening is 15,200 pt/cc. PM2.5/PM10 mass ratios are 0.65 ± 0.05, 0.75 ± 0.05, and 0.78 ± 0.09 for Bafoussam, Bamenda, and Yaounde, respectively. Elemental carbon (EC) and organic carbon (OC) contribution to PM2.5 in Bafoussam, Bamenda, and Yaoundé are 3.9%, 2.9% and 12% for EC and 17.7%, 23.6%, and 34.2% for OC, respectively. After conducting spatial variability of PM mass concentration and size fractionation sampling at various locations within each of the three cities, we find that PM2.5 averages are highest during commercial meal preparation in Bafoussam (684 ± 546 μg/m3), and on the road in Bamenda (417 ± 113 μg/m3) and Yaoundé (110 ± 57 μg/m3). Additional air quality research in Central and West Africa is necessary to begin implementing policy steps that influence change and to advocate for improved health conditions in this rapidly expanding region of the world.

Global perspective on the oxidative potential of airborne particulate matter: a synthesis of research findings.

An emerging hypothesis in the field of air pollution is that oxidative stress is one of the important pathways leading to adverse health effects of airborne particulate matter (PM). To advance our understanding of sources and chemical elements contributing to aerosol oxidative potential and provide global comparative data, we report here on the biological oxidative potential associated with size-segregated airborne PM in different urban areas of the world, measured by a biological (cell-based) reactive oxygen species (ROS) assay. Our synthesis indicates a generally greater intrinsic PM oxidative potential as well as higher levels of exposure to redox-active PM in developing areas of the world. Moreover, on the basis of our observations, smaller size fractions are generally associated with higher intrinsic ROS activity compared with larger PM size fractions. Another important outcome of our study is the identification of major species and sources that are associated with ROS activity. Water-soluble transition metals (e.g., Fe, Ni, Cu, Cr, Mn, Zn and V) and water-soluble organic carbon (WSOC) showed consistent correlations with the oxidative potential of airborne PM across different urban areas and size ranges. The major PM sources associated with these chemical species include residual/fuel oil combustion, traffic emissions, and secondary organic aerosol formation, indicating that these sources are major drivers of PM-induced oxidative potential. Moreover, comparison of ROS activity levels across different seasons indicated that photochemical aging increases the intrinsic oxidative potential of airborne PM.

Modeling spatiotemporal variability of intra-urban air pollutants in Detroit: A pragmatic approach

This study combined a three-year time series of air pollutant measurements from the Michigan Air Sampling Network (MASN) with spatially detailed datasets for two two-week periods in September 2008 and June 2009. The objective was to produce monthly pollutant concentration models for the city of Detroit, Michigan, USA from January 2008 through December 2010, in support of a related epidemiological study examining adverse birth outcomes in Detroit. Two gaseous analytes, NO2 (nitrogen dioxide) and total BTEX (benzene, toluene, ethyl-benzene, and xylene), as well as two particulate matter size fractions, PM2.5 and PM10, were investigated. The September 2008 and June 2009 datasets were modeled using ordinary kriging to produce high spatial density concentration maps with 300 m by 300 m resolution across the city. A weighted average was applied to these maps to generate a series of monthly spatial models for each pollutant. Temporal variability was then incorporated by adjusting each monthly spatial model using an average bulk shift derived from MASN time series measurements for the corresponding month over the three-year study period.The resulting models incorporate temporal trends while preserving neighborhood scale spatial variability. Seasonal variation was evident in NO2 models, but not readily discernable in BTEX or PM models across the three year study period. The greatest spatial and temporal variability was observed in the BTEX distributions, which are inferred to be strongly influenced by local sources. The methodology employed assumes that the interpolated monthly models adequately capture spatial variability of the air pollutants across the study area, the spatial distribution of pollutant concentrations remained consistent while their magnitude fluctuated from month to month, and that the available time series measurements reflect temporal trends across the city of Detroit throughout the three-year study period.

Abstract P250: Thr715pro Polymorphism in the Platelet Selectin Gene Does Not Modify Effects of Air Pollution Exposure.

Background: Epidemiological and toxicological studies support an adverse effect of air pollution exposure on cardiovascular outcomes, and proposed mechanisms include increased thrombosis and coagulation. Previously, we showed increased plasma levels of soluble platelet selectin (sP-selectin) and increased expression of the platelet selectin gene ( SELP ) in association with higher air pollution exposure; both indicating probable increased platelet activation. A functional polymorphism in SELP , Thr715Pro, decreases circulating levels of sP-selectin and is associated with decreased risk for venous thromboembolism and myocardial infarction. We hypothesized that carriers of the Pro allele would have weaker associations of gene expression and protein level with air pollution exposure versus non-carriers. Methods: We used a cohort-panel design, with repeated measures of exposures and outcomes among 60 elderly, non-smoking subjects with coronary artery disease, living in the Los Angeles air basin. This population is shown to have higher susceptibility to pollutant exposure. We measured plasma sP-selectin levels weekly for all 60 subjects using an ELISA assay. Genotypes were determined using restriction fragment length polymorphism analysis. Whole blood gene expression levels were measured using quantitative polymerase chain reactions, for a subset of 40 subjects. Pollutant exposures measured at subject residences included the following: NO 2 /NO x , O 3 , CO, PM 2.5 organic, elemental and black carbon; particulate matter size fractions (PM 0.25 , PM 0.25-2.5 , PM 2.5-10 ); and organic components and oxidative potential of PM. Primary and secondary organic carbon were estimated from total organic carbon. T-tests and linear mixed effects models were used to analyze the data. Results: We determined that the 12 subjects who were carriers of the protective, Pro715, allele had lower sP-selectin levels versus Thr715 homozygotes (34.78 ng/mL vs 42.03 ng/mL, p&lt;0.001 by t-test). Pro715 allele carriers also had 0.396-fold lower SELP expression versus Thr715 homozygotes (p&lt;0.005). However, in pollutant models, there was no significant interaction between carrier status and pollutant level (p-value= 0.1 or greater). Conclusions: While it appears that both SELP gene and protein expression increases in association with air pollution exposure and these levels are lower in Pro715 carriers, we found no effect modification of these relationships by genotype. Recent data suggests that lower plasma sP-selectin in 715Pro carriers results from decreased N-glycosylation and subsequent sequestration in the Golgi apparatus. To our knowledge, there is no data indicating that N-glycosylation changes as a result of air pollution exposure. We conclude that differences in the soluble protein levels due to the presence of this polymorphism are not altered as a result of changes in air pollution exposure.

Airborne particulate matter in school classrooms of northern Italy.

Indoor size-fractioned particulate matter (PM) was measured in seven schools in Milan, to characterize their concentration levels in classrooms, compare the measured concentrations with the recommended guideline values, and provide a preliminary assessment of the efficacy of the intervention measures, based on the guidelines developed by the Italian Ministry of Healthand applied to mitigate exposure to undesirable air pollutants. Indoor sampling was performed from Monday morning to Friday afternoon in three classrooms of each school and was repeated in winter 2011–2012 and 2012–2013. Simultaneously, PM2.5 samples were also collected outdoors. Two different photometers were used to collect the PM continuous data, which were corrected a posteriori using simultaneous gravimetric PM2.5 measurements. Furthermore, the concentrations of carbon dioxide (CO2) were monitored and used to determine the Air Exchange Rates in the classrooms. The results revealed poor IAQ in the school environment. In several cases, the PM2.5 and PM10 24 h concentrations exceeded the 24 h guideline values established by the World Health Organization (WHO). In addition, the indoor CO2 levels often surpassed the CO2 ASHRAE Standard. Our findings confirmed that important indoor sources (human movements, personal clouds, cleaning activities) emitted coarse particles, markedly increasing the measured PM during school hours. In general, the mean PM2.5 indoor concentrations were lower than the average outdoor PM2.5 levels, with I/O ratios generally <1. Fine PM was less affected by indoor sources, exerting a major impact on the PM1–2.5 fraction. Over half of the indoor fine particles were estimated to originate from outdoors. To a first approximation, the intervention proposed to reduce indoor particle levels did not seem to significantly influence the indoor fine PM concentrations. Conversely, the frequent opening of doors and windows appeared to significantly contribute to the reduction of the average indoor CO2 levels.

Indoor Air Quality in the United Arab Emirates

Air quality was measured inside 628 United Arab Emirates (UAE) personal residences. Weekly average concentrations of carbon monoxide (CO), formaldehyde (HCHO), hydrogen sulfide (H2S), nitrogen dioxide (NO2), sulfur dioxide (SO2), and three size fractions of particulate matter (PM2.5, PMc, and PM10) were determined in each home. In a subset of the homes, measurements of outdoor air quality, ultrafine PM concentrations, and elemental PM concentrations were also made. Questionnaires were administered to obtain information on housing demographics and lifestyle habits. Air measurements were performed using simple and cost effective passive samplers. The 90th percentiles of indoor CO, HCHO, H2S, NO2, and SO2 were 1.55 ppm, 0.05 ppm, 0.12 ppm, 0.01 ppm, and 0.05 ppm, respectively. Median indoor PM2.5, PMc, and PM10, concentrations were 5.73 μg/m3, 29.4 μg/m3, and 35.2 μg/m3, respectively. The median indoor concentration of ultrafine PM was 3.62 × 1010 particles/m3. Indoor/outdoor ratios for PM were 0.44, 0.41, and 0.38 for ultrafine PM, PM2.5, and PM10, respectively. These values fall within the range of other indoor air studies findings conducted in developing countries. Air conditioning, smoking, and attached kitchens were significantly correlated with indoor levels of carbon monoxide. In addition, indoor concentrations of PM2.5 and PM10 were significantly correlated with vehicles parked within five meters of the home, central air conditioning, and having attached kitchens. This is the first robust indoor air quality data set developed for the UAE. This study demonstrates that screening level tools are a good initial step for assessing air quality when logistical issues (distance, language, cultural, training) and intrusion into personal lives need to be minimized.

The combined effects of physicochemical properties of size-fractionated ambient particulate matter on in vitro toxicity in human A549 lung epithelial cells

Epidemiological and toxicological studies have suggested that the health effects associated with exposure to particulate matter (PM) are related to the different physicochemical properties of PM. These effects occur through the initiation of differential cellular responses including: the induction of antioxidant defenses, proinflammatory responses, and ultimately cell death. The main objective of this study was to investigate the effects of size-fractionated ambient PM on epithelial cells in relation to their physicochemical properties. Concentrated ambient PM was collected on filters for three size fractions: coarse (aerodynamic diameter [AD] 2.5–10 μm), fine (0.15–2.5 μm), and quasi-ultrafine (<0.2 μm), near a busy street in Toronto, Ontario, Canada. Filters were extracted and analyzed for chemical composition and redox activity. Chemical analyses showed that the coarse, fine, and quasi-ultrafine particles were comprised primarily of metals, water-soluble species, and organic compounds, respectively. The highest redox activity was observed for fine PM. After exposure of A549 cells to PM (10–100 μg/ml) for 4 h, activation of antioxidant, proinflammatory and cytotoxic responses were assessed by determining the expression of heme oxygenase (HMOX-1, mRNA), interleukin-8 (IL-8, mRNA), and metabolic activity of the cells, respectively. All three size fractions induced mass-dependent antioxidant, proinflammatory, and cytotoxic responses to different degrees. Quasi-ultrafine PM caused significant induction of HMOX-1 at the lowest exposure dose. Correlation analyses with chemical components suggested that the biological responses correlated mainly with transition metals and organic compounds for coarse and fine PM and with organic compounds for quasi-ultrafine PM. Overall, the observed biological responses appeared to be related to the combined effects of size and chemical composition and thus both of these physicochemical properties should be considered when explaining PM toxicity.

Comparison of how ambient PMc and PM2.5 influence the inflammatory potential

Airborne particulate matter (PM) is one of the six criteria air pollutants currently regulated by the U.S. Environmental Protection Agency (EPA), with existing ambient standards for PM2.5 and PM10. Currently there are no health-based regulations for the size fraction between 2.5 and 10 µm, commonly known as the coarse fraction (PMc). The present study investigates current gaps in knowledge for PMc including exposure toxicity and PM ratios (PMc:PM2.5) in PM10. Throughout the world, all the three PM size fractions have been shown to be associated with adverse impacts. Recent studies have shown that PMc can be more detrimental to susceptible populations when directly compared to PM2.5, and that the PMc fraction in PM10 can account for the majority of the inflammatory response from PM10 exposure. In our studies we utilized a bone marrow-derived mouse macrophage in vitro system to compare the inflammatory potential of PMc, PM2.5 and mixtures of the two. The result was a linear increase in interleukin(IL) -1β with increasing levels of exposure to winter and summer PMc, as compared to PM2.5, which exhibited logarithmic growth. Also, exposure to PM10 as a function of PM2.5 and PMc mass ratios showed that IL-1β and TNF-α levels increased synergistically with a greater burden of PMc. Endotoxin content in the PM did not correlate with these results, suggesting that other activators in PMc are likely responsible for activating the NF-κB pathway and the inflammasome.

Trace metals in size-fractionated particulate matter in a Portuguese hospital: exposure risks assessment and comparisons with other countries

Hospitals are considered as a special and important type of indoor public place where air quality has significant impacts on potential health outcomes. Information on indoor air quality of these environments, concerning exposures to particulate matter (PM) and related toxicity, is limited though. This work aims to evaluate risks associated with inhalation exposure to ten toxic metals and chlorine (As, Ni, Cr, Cd, Pb, Mn, Se, Ba, Al, Si, and Cl) in coarse (PM2.5-10) and fine (PM2.5) particles in a Portuguese hospital in comparison with studies representative of other countries. Samples were collected during 1 month in one urban hospital; elemental PM characterization was determined by proton-induced X-ray emission. Noncarcinogenic and carcinogenic risks were assessed according to the methodology provided by the United States Environmental Protection Agency (USEPA; Region III Risk-Based Concentration Table) for three different age categories of hospital personnel (adults, >20, and <65 years) and patients (considering nine different age groups, i.e., children of 1-3 years to seniors of >65 years). The estimated noncarcinogenic risks due to occupational inhalation exposure to PM2.5-bound metals ranged from 5.88 × 10(-6) for Se (adults, 55-64 years) to 9.35 × 10(-1) for As (adults, 20-24 years) with total noncarcinogenic risks (sum of all metals) above the safe level for all three age categories. As and Cl (the latter due to its high abundances) were the most important contributors (approximately 90 %) to noncarcinogenic risks. For PM2.5-10, noncarcinogenic risks of all metals were acceptable to all age groups. Concerning carcinogenic risks, for Ni and Pb, they were negligible (<1 × 10(-6)) in both PM fractions for all age groups of hospital personnel; potential risks were observed for As and Cr with values in PM2.5 exceeding (up to 62 and 5 times, respectively) USEPA guideline across all age groups; for PM2.5-10, increased excess risks of As and Cr were observed particularly for long-term exposures (adults, 55-64 years). Total carcinogenic risks highly (up to 67 times) exceeded the recommended level for all age groups, thus clearly showing that occupational exposure to metals in fine particles pose significant risks. If the extensive working hours of hospital medical staff were considered, the respective noncarcinogenic and carcinogenic risks were increased, the latter for PM2.5 exceeding the USEPA cumulative guideline of 10(-4). For adult patients, the estimated noncarcinogenic and carcinogenic risks were approximately three times higher than for personnel, with particular concerns observed for children and adolescents.

Composition and effects of inhalable size fractions of atmospheric aerosols in the polluted atmosphere. Part II. In vitro biological potencies

Exposure to particulate matter (PM) in ambient air has been shown to lead to adverse health consequences. Six size fractions of PM with aerodynamic diameter smaller than 10μm (PM10) and gas phase were collected at six localities with different major pollution sources. Extracts of samples were assessed for AhR-mediated toxicity, (anti-)estrogenicity, (anti-)androgenicity and genotoxicity. The biological responses were interpreted relative to chemical characterization. Historically, for regulatory purposes, evaluation of air pollution was based mainly on assessment of the sum of PM10. In the case of AhR-mediated activity, PM1 was responsible for more than 75% of the activity of the particulate fraction from all localities. The assessed effects were correlated with concentrations of polycyclic aromatic hydrocarbons (PAH), organic carbon content and specific surface area of the PM. A significant proportion of biologically active chemicals seems to be present in the gas phase of air. The results suggest that an average daily exposure based just on the concentrations of contaminants contained in PM10, as regulated in EU legislation so far, is not a sufficient indicator of contaminants in air particulates and adoption of standards more similar to other countries and inclusion of other parameters besides mass should be considered.

Temporal Variation of Size-Fractionated Particulate Matter and Carbon Monoxide in Selected Microenvironments of the Milan Urban Area

This article focuses on air pollution in specific urban microenvironments and conditions characterized by high relative concentration levels and by possible risk to human health. For this reason, monitoring of particle number concentration (PNC) with a wide, size-resolved particle-size range, and CO (an indicator of combustion sources, e.g., traffic), was performed in a variety of microenvironments. Concentrations of ultrafine particles (UFPs), size-fractionated particulate matter (PM), and carbon monoxide (CO) were measured in the central area of Milan over three-week-long periods, one each during summer, autumn, and winter, with three monitoring sessions per day. Experimental data were collected continuously during each monitoring period along an established urban pathway. To assess the relevance of time and spatial factors affecting atmospheric concentrations of UFPs, PM, and CO data were collected while walking or moving by different private and public means of transport. Measurements were divided on the basis of different microenvironments (MEs), seasons, days of the week, and periods of the day. Data analysis shows statistically significant differences across MEs and monitoring periods. The highest measured median concentrations and data variability were observed for busy streets, walking or moving by motorized vehicle (CO, UFP) and in metro trains (PM); the lowest concentrations were observed in park areas and in indoor environments. The highest concentrations were measured during working day morning monitoring sessions. Regarding seasonal variation, UFP, PM, and CO showed different patterns: the highest median concentrations were observed in summer for CO, and in autumn and winter for the UFP and PM. Appreciable differences among all MEs and monitoring periods were observed: concentration patterns and variations appear related to typical sources of urban pollutants (traffic), proximity to sources, and time of day. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing Table VI: Tau b (Kendall) index for non–parametric correlation tau test.]

Oxidative potential and chemical speciation of size-resolved particulate matter (PM) at near-freeway and urban background sites in the greater Beirut area

To assess particle oxidative potential in the greater Beirut area, size-resolved PM10–2.5, PM2.5–0.25 and PM0.25 samples were collected at near-freeway and urban background sites. Metals and trace elements, including Mn, Cr, Cu, Ba, Mo and Sb, displayed increased levels and crustal enrichment factors at the roadway, indicating their vehicular origin. These elements in addition to Co, V, Ni and Zn were mostly distributed in PM2.5–0.25 and PM0.25 at both sites, with moderate-to-high water-solubility (>30%). The presence of these metals, mainly air toxics, in small size ranges constitutes an added health risk. Of particular concern are elements with strong correlations (R≥0.70) with reactive oxygen species (ROS)-activity, measured by a cellular assay. In PM10–2.5, road dust component Mn and soil-related element Co were highly correlated with ROS-activity. In PM2.5–0.25, vehicular abrasion element Cu and soil-derived component Co were highly associated with ROS-activity. In PM0.25, V and Ni, originating from fuel oil combustion, strongly correlated with ROS formation. ROS-activity displayed a particle-size dependency, with lowest activity associated with PM10–2.5. On a per air volume basis, size-resolved ROS-activity was 1.5–2.8 times greater at the roadside than background location, indicating that exposure to redox-active species may be greatest near the freeway. Size-fractionated PM intrinsic activity (i.e. PM mass-normalized) was comparable at both sites, possibly suggesting a similarity in the sources of ROS-active species. Relative to other urban settings, while the intrinsic redox activity of PM10–2.5 in Beirut is comparable to that measured at an urban site in Los Angeles (LA), its PM0.25-induced ROS-activity is ~2.3-fold greater. Moreover, the intrinsic ROS-activity of ambient PM2.5 in Beirut is comparable to that reported in Milan-Italy, but 3.1-times PM2.5 activity in the heavily-polluted Lahore-Pakistan. Lastly, findings suggest a dominant role of transition metals in generating ROS compared to organic carbon in the LA area.

Short-term effects of fine and coarse particles on mortality and morbidity in 4 Mediterranean countries

Background and Aims: Few studies have investigated the independent health effects of different size fractions of particulate matter (PM), in multiple locations, especially in Europe. We investigate...

Particulate matter air pollution and risk of Multiple Sclerosis in a large study of female nurses.

Background: Multiple Sclerosis (MS) is a common autoimmune disorder of the nervous system of unknown origin. The incidence of MS is increasing throughout the world, but the specific reason for this increase has not been identified. Cigarette smoking, whose effects on the immune and nervous system are thought to be similar to air pollution, has consistently been associated with increased MS risk, as well as worse progression of MS. Aims: In this study, we used data from a large prospective study on US women to examine whether there is an association between particulate matter (PM) air pollution and risk of MS. Methods: This study included participants from an ongoing prospective cohort study, the Nurses’ Health Study II (NHS II). Cumulative average exposure to different size fractions of PM up to the time of MS onset, was estimated using a spatio-temporal model by linking each individual’s places of residence throughout the study with location-specific air pollution levels. We used multivariable Cox proportional hazards models to estimate the risk of MS associated with PM10, PM2.5 and PM10-2.5, adjusting for smoking, body mass index at age 18, ethnicity, population density, region, season, birth tier, income and housing value. Results: Overall, we found no significant associations between PM2.5, PM10-2.5, or PM10 exposure and MS risk. The RR comparing the top quintile to the bottom quintile of exposure was 1.30 (95% CI: 0.84, 2.01), 0.94 (95% CI: 0.65, 1.37) and 1.13 (95% CI: 0.76, 1.65) for PM10, PM2.5 and PM10-25, respectively. In sensitivity analyses among never smokers, we did not find significant associations for any of the exposures of interest. Conclusions: In this study, we did not find convincing evidence that exposure to air pollution during adulthood is a risk factor for MS.

Individual exposure to size-fractionated particulate matter and carbon monoxide in selected microenvironments of the Milan urban area

Background Human exposure in transport micro-environments (MEs) is of particular interest because many citizens and commuters spend a substantial component of their time in these spaces. Fixed monitoring stations measuring outdoor air quality are used to estimate exposure levels, however, this approach may significantly underestimate the exposure of particular population subgroups, pointing to the need for direct personal exposure measurements. Aims Ultrafine particles (UFPs), size-fractionated particulate matter (PM) and carbon monoxide (CO) were measured in the central area of Milan, in order to assess the influence of time and space on individual exposures. Methods Individual exposures to CO (passive analyser - electrochemical cell), UFPs and PM (Condensation and Optical Particle Counters) were continuously collected along an established urban pathway, moving afoot or by different private and public means of transport during three week-long periods (summer, autumn and winter) and through three sampling sessions per day. Results The analysis of the exposure measures showed statistically significant differences between different MEs and sampling periods. The highest mean concentrations were observed during time spent along busy streets (walking or moving by motorized vehicles), in metro trains and on working-day mornings; the lowest exposures were observed in green areas and in indoor environments. PM and CO showed different seasonal behaviours: the highest mean concentrations were observed in summer for CO and for the coarser fractions of PM, and in winter for the finer fractions of PM. Conclusions Appreciable differences among MEs and sampling periods were observed. Exposure patterns appeared to be mostly related to the proximity to traffic sources, to peculiarities of MEs, as well as to time periods during the day, days of the week, and seasons of the year.

Time-series analysis of mortality effects from airborne particulate matter size fractions in Beijing

Evidence concerning the health risk of fine and coarse particles is limited in developing Asian countries. The modifying effect between particles and temperature and season also remains unclear. Our study is one of the first to investigate the acute effect of particles size fractions, modifying effects and interannual variations of relative risk in a developing megacity where particulate levels are extraordinarily high compared to other Asian cities. After controlling for potential confounding, the results of a time-series analysis during the period 2005–2009 show that a 10 μg m−3 increase in PM2.5 levels is associated with a 0.65% (95% CI: 0.29–0.80%), 0.63% (95% CI: 0.25–0.83%), and 1.38% (95% CI: 0.51–1.71%) increase in non-accidental mortality, respiratory mortality, and circulatory mortality, respectively, while a 10 μg m−3 increase in PM10 is similarly associated with increases of 0.15% (95% CI: 0.04–0.22%), 0.08% (95% CI: 0.01–0.18%), and 0.44% (95% CI: 0.12–0.63%). We did not find a significant effect of PM2.5–10 on daily mortality outcomes. Our analyses conclude that temperature and particulates, exposures to both of which are expected to increase with climate change, might act together to worsen human health in Beijing, especially in the cool seasons. The level of the estimated percentage increase assume an escalating tendency during the study period, in addition to having a low value in 2008, and after the Olympic Games, the values increased significantly as the temporary atmospheric pollution control measures were terminated mostly.

Redox activity and PAH content in size-classified nanoparticles emitted by a diesel engine fuelled with biodiesel and diesel blends

Diesel and biodiesel emissions are important sources of ambient air pollution. Therefore, the influence of using different blending percentages of biodiesel to diesel as fuel on redox activity, particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) emission profiles, and the corresponding carcinogenicity index (BaPE) size distributions are not well known. In this way, the present work aims to investigate the effect of diesel/biodiesel blends on the physical, chemical, and toxicological properties of diesel engine exhaust at low condition, through the study of the changes in size-distribution and emission factors of PAH associated to PM, corresponding carcinogenicity index (BaPE) size distributions and PM redox activity. For that, particle emissions from commercial petroleum-based diesel with 4% of soy biodiesel (B4), a biodiesel blend of 25% and 50% (B25 and B50) and also pure biodiesel (B100) were measured on a steady-state dynamometer in a test using a diesel engine at low load. Size-fractionated PM samples were collected by using the NanoMOUDI impactor and analyzed for the 16 priority PAH by HPLC–fluorescence detector. In addition, PM2.5 samples were collected and analyzed for redox activity by DTT assay. PM was distributed in all sizes, while PAH size distribution was found in higher levels in the accumulation mode (30nm<Dp<2.5μm). Total PAH emission factors (ng kgfuel-1) for B4, B25, B50 and B100 were: 237,111,182 and 319ng kgfuel-1, respectively. Individual PAH emission factors showed that PAH containing four or more rings (MW>202) such as BBF, BAA, PYR and BGP were the main PAH emitted by the four studied fuels. The percentage reductions of individual PAH emission factors for the blend fuels in comparison with B4 were 37% and 22% for B25 and B50, respectively, and an increase around 31% for B100. On the other hand it was observed increase in redox activity for B25, B50 and B100 when compared to B4. In general, the results from our study suggest that emissions from pure waste cooking biodiesel may not be the better fuel choice in terms of PM, PAH and BaPE particle size distribution and emission factors as well as redox activity. However, B25 and B50 blends presented some improvements in terms of PM, HPA, BaPE size distribution and redox activity of engine exhaust in comparison to B4. This suggests that addition of low percentages of biodiesel to diesel promotes benefices in both environmental and human health concerns.

Ambient Air Pollution Exposures and Risk of Rheumatoid Arthritis

Environmental factors may play a role in the development of rheumatoid arthritis (RA). We previously observed increased RA risk among women living closer to major roads (a source of air pollution). Herein, we examined whether long-term exposures to specific air pollutants were associated with RA risk among women in the Nurses' Health Study (NHS). The NHS is a large US cohort of female nurses followed up prospectively every 2 years since 1976. We studied 111,425 NHS participants with information on air pollution exposures as well as data concerning other lifestyle and behavioral exposures and disease outcomes. Outdoor levels of different size fractions of particulate matter (PM10 and PM2.5 ) and gaseous pollutants (SO2 and NO2 ) were predicted for all available residential addresses using monitoring data from the US Environmental Protection Agency. We examined the association of time-varying exposures 6 and 10 years before each questionnaire cycle and cumulative average exposure with the risk of RA, seronegative (rheumatoid factor and anti-citrullinated peptide antibody negative) RA, and seropositive RA. Over the 3,019,424 person-years of followup, 858 incident RA cases were validated by medical record review by 2 board-certified rheumatologists. Overall, we found no evidence of increased risk of RA, seronegative RA, or seropositive RA with exposure to the different pollutants and little evidence of effect modification by socioeconomic status or smoking status, geographic region, or calendar period. In this group of socioeconomically advantaged middle-aged and elderly women, adult exposures to air pollution were not associated with an increased RA risk.

Short-term effects of PM2.5, PM10 and PM2.5–10 on daily mortality in the Netherlands

IntroductionInformation on the relationship between levels of particulate matter (PM) smaller than 2.5μm and mortality rates in Europe is relatively sparse because of limited availability of PM2.5 measurement data. Even less information is available on the health effects attributable to PM2.5–10, especially for North-West Europe. ObjectivesTo investigate the relationship between various PM size fractions and daily mortality rates. MethodsDaily concentrations of PM from the Dutch National Ambient Air Quality Monitoring Network as well as all cause and cause-specific mortality rates in the Netherlands were obtained for the period 2008–2009. Poisson regression analysis using generalized additive models was used, with adjustment for potential confounding including long-term and seasonal trends, influenza incidence, meteorological variables, day of the week, and holidays.Different measures of PM (PM2.5, PM10 and PM2.5–10) were analysed. ResultsPM10 and PM2.5 levels were statistically significantly (p<0.05) associated with all cause and cause-specific deaths. For example, a 10μg/m3 increase in previous day PM was associated with 0.8% (95% CI 0.3–1.2) excess risk in all cause mortality for PM2.5 and a 0.6% (CI 0.2–1.0) excess risk for PM10. No appreciable associations were observed for PM2.5–10. Effects of PM10, and PM2.5 were insensitive to adjustment for PM2.5–10, and vice-versa. PM10 and PM2.5 were too highly correlated to disentangle their independent effects. ConclusionsPM10 and PM2.5 both were significantly associated with all cause and cause-specific mortality. We were unable to demonstrate significant effects for PM2.5–10, possibly due to the lower temporal variability and the higher exposure misclassification in PM2.5–10 compared to PM10 or PM2.5. The lack of effects of PM2.5–10 in our study should therefore not be interpreted as an indication that PM2.5–10 can be considered harmless.