Chemical composition of fine particles in fresh smoke plumes from boreal wild-land fires in Europe

Identification of the phase composition of solid microparticles in the nasal mucosa of patients with chronic hypertrophic rhinitis using Raman microspectroscopy

Solid particles, predominantly in micron and submicron sizes, have repeatedly been observed as a threat to a human health unique compared to the other textures of the same materials. In this work, the hypothesis the solid metal-based particles play a role in the pathogenesis of chronic hypertrophic rhinitis was investigated in patients who had not responded positively to medication. In the group of 40 randomly selected patients indicated for surgical mucotomy, the presence of solid micro- and submicron particles present in their nasal mucosa was assessed. For comparison, a set of 13 reference samples from patients without diagnosed chronic hypertrophic rhinitis was evaluated. The analysis was performed using Raman microspectroscopy. The advantage of this method is the direct identification of compounds. The main detected compounds in the mucosa samples of patients with chronic hypertrophic rhinitis were TiO2, carbon-based compounds, CaCO3, Ca(Fe, Mg, Mn)(CO3)2 MgCO3, Fe2O3, BaSO4, FeCO3 and compounds of Al and Si, all of which may pose a health risk to a living organism. In the reference samples, only TiO2 and amorphous carbon were found. In the control group mucosa, a significantly lower presence of most of the assessed compounds was found despite the longer time they had to accumulate them due to their higher mean age. Identification and characterisation of such chemicals compounds in a living organism could contribute to the overall picture of the health of the individual and lead to a better understanding of the possible causes not only in the chronic hypertrophic rhinitis, but also in other mucosal and idiopathic diseases.

Optimization of a sequential extraction procedure for trace elements in Arctic PM10

In this work, a two-step sequential extraction scheme for the determination of trace elements in Arctic PM₁₀ samples was optimized by using two certified reference materials (CRMs). By means of an experimental design for qualitative variables, the five most common extracting solutions for particulate matter (PM) sequential extraction (high purity water (HPW), 0.032 M HNO₃, 0.022 M HCl, 0.11 M CH₃COOH, and 0.012 M CH₃COOH/CH₃COONH₄ buffer) and two different extraction methods (stirring and ultrasounds) were compared. The purpose of the study was the identification of the procedure which gives the best estimation of the anthropogenic portion of the elements present in PM₁₀ samples. The use of ultrasounds instead of stirring induced a low but significant decrease of the extraction of all the elements and a decrease in the repeatability of the procedure. Diluted HNO₃ was the extractant which allowed to maximize the extraction of anthropogenic elements (As, Cd, Pb, Zn) with respect to crustal ones (Al, Si, Ti). The optimized procedure proved successful in avoiding contaminations and, therefore, suitable to be applied to PM samples having extremely low concentrations, such as samples collected in polar or other remote areas. The chosen procedure was applied to ten Arctic PM₁₀ samples, allowing for a better identification of their sources. Indeed, it was possible to hypothesize that even though the concentrations of As, Cd, K, Mg, Mn, and Ni in spring and summer were different, their mobility and, therefore, their chemical form in the analyzed PM₁₀ samples were probably similar.

Surface ozone climatology of South Eastern Brazil and the impact of biomass burning events

In the austral spring, biomass fires affect a vast area of South America each year. We combined in situ ozone (O₃) data, measured in the states of São Paulo and Paraná, Brazil, in the period 2014-2017, with aerosol optical depth, co-pollutants (NOx, PM_2.5 and PM₁₀) and air backtrajectories to identify sources, transport and geographical patterns in the air pollution data. We applied cluster analysis to hourly O₃ data and split the investigation area of approximately 290,000 km² into five groups with similar features in terms of diurnal, weekly, monthly and seasonal O₃ concentrations. All groups presented a peak in September and October, associated with the fire activities and enhanced photochemistry. The highest mean O₃ concentrations were measured inland whilst, besides having lower concentrations, the coastal group was also associated with the smallest diurnal and seasonal variations. The latter was attributed to lower photochemical activity due to frequently occurring overcast weather situation. The mean annual regional contribution of O₃ over the area was 61 μg/m³, with large seasonal and intersite variabilities (from 35 to 84 μg/m³). The long-range transport of smoke contributed with between 23 and 41% of the total O₃ during the pollution events. A pollution outbreak in September 2015 caused many-fold increases in O₃, PM_2.5 and PM₁₀ across the investigation area, which exceeded the World Health Organisation recommendations. We show that the regional transport of particulates and gas due to biomass burning overlays the local emissions in already highly polluted cities. Such an effect can outweigh local measures to curb anthropogenic air pollution in cities.

Influence of biomass burning on local air pollution in mainland Southeast Asia from 2001 to 2016

In this study, various remote sensing data, modeling data and emission inventories were integrated to analyze the tempo-spatial distribution of biomass burning in mainland Southeast Asia and its effects on the local ambient air quality from 2001 to 2016. Land cover changes have been considered in dividing the biomass burning into four types: forest fires, shrubland fires, crop residue burning and other fires. The results show that the monthly average number of fire spots peaked at 34,512 in March and that the monthly variation followed a seasonal pattern, which was closely related to precipitation and farming activities. The four types of biomass burning fires presented different tempo-spatial distributions. Moreover, the monthly Aerosol Optical Depth (AOD), concentration of particulate matter with a diameter less than 2.5 μm (PM_2.5) and carbon monoxide (CO) total column also peaked in March with values of 0.62, 45 μg/m³ and 3.25 × 10¹⁸ molecules/cm², respectively. There are significant correlations between the monthly means of AOD (r = 0.74, P < 0.001), PM_2.5 concentration (r = 0.88, P < 0.001), and CO total column (r = 0.82, P < 0.001) and the number of fire spots in the fire season. We used Positive Matrix Factorization (PMF) model to resolve the sources of PM_2.5 into 3 factors. The result indicated that the largest contribution (48%) to annual average concentration of PM_2.5 was from Factor 1 (dominated by biomass burning), followed by 27% from Factor 3 (dominated by anthropogenic emission), and 25% from Factor 2 (long-range transport/local nature source). The annually anthropogenic emission of CO and PM_2.5 from 2001 to 2012 and the monthly emission from the Emission Database for Global Atmosphere Research (EDGAR) were consistent with PMF analysis and further prove that biomass burning is the dominant cause of the variation in the local air quality in mainland Southeast Asia.

The impact of wildfire smoke on compositions of fine particulate matter by ecoregion in the Western US

Epidemiological studies of wildfire PM_2.5 constituents are hindered by the limited information on the population exposure to ambient PM_2.5 constituents during high-pollution episodes from wildfires ("smoke waves"). The chemical composition of wildfire-related PM_2.5 can be affected by different ecosystems. Current literature assessing the differences in PM_2.5 pollution from wildfire smoke by ecosystems often analyzes air samples collected from the smoke near the center of an individual fire, but the results might not represent the exposure of the general public living away from the fire center but affected by the smoke of the fire. We assessed the population-based exposure to wildfire-related PM_2.5 species by integrating monitor measurements on 29 PM_2.5 species and previous findings on smoke waves during 2004-2009 in 51 Western US counties across six ecoregions. We found that across all ecoregions, smoke waves were associated with an increase in the fraction of organic carbon of total PM_2.5 by 20 percentage points (95% confidence interval (CI): 17, 23), an increase in the fraction of elemental carbon by 0.99 percentage points (95% CI: 0.43, 1.6), and decreases in fractions of sulfate and crustal species. While the PM_2.5 mixtures were dominated by the same source (wildfires), compositions in North American Deserts and the Great Plains during smoke waves were distinct. Besides expanding the knowledge of wildfire PM_2.5, our study has implications beyond wildfires and could aid future population-based epidemiological research on PM_2.5 mixtures by source and region.

Diversity of tetracycline- and erythromycin-resistant bacteria in aerosols and manures from four types of animal farms in China

Confined animal feeding operations generate high levels of airborne antibiotic-resistant bacteria, including pathogenic strains that may pollute the local environment or pose a health risk to both animals and workers. However, the communities of airborne antibiotic-resistant bacteria in such operations are not fully understood, especially in fine particles that penetrate deeply into the respiratory system. To address these gaps, manures and aerosols from inside and outside of animal houses were collected, and the characteristics of antibiotic-resistant bacteria were analyzed using Illumina MiSeq sequencing to amplify the V3-V4 region of bacterial 16S rRNA. The results indicated that animal species was the main factor that influenced the bacterial community of both manure and aerosol samples, while antibiotic selection was the major factor that influenced the bacterial community of aerosol samples from the inside of animal houses. An obvious clustering difference was detected between manure and aerosol samples. No significant difference in both alpha- and beta-diversity indices was detected between fine and coarse particles. As a key genus, Staphylococcus was found to drive the difference in the bacterial community of tetracycline-resistant bacteria to total culturable bacteria and erythromycin-resistant bacteria and also the difference in the bacterial community from aerosol to manure samples. Current data would help in evaluating the risk to human and livestock health and tracing the source of airborne antibiotic-resistant bacteria in animal farms.

The impact of the 2016 Fort McMurray Horse River Wildfire on ambient air pollution levels in the Athabasca Oil Sands Region, Alberta, Canada

An unprecedented wildfire impacted the northern Alberta city of Fort McMurray in May 2016 causing a mandatory city wide evacuation and the loss of 2,400 homes and commercial structures. A two-hectare wildfire was discovered on May 1, grew to ~157,000ha by May 5, and continued to burn an estimated ~590,000ha by June 13. A comprehensive air monitoring network operated by the Wood Buffalo Environmental Association (WBEA) in and around Fort McMurray provided essential health-related real-time air quality data to firefighters during the emergency, and provided a rare opportunity to elucidate the impact of gaseous and particulate matter emissions on near-field communities and regional air pollution concentrations. The WBEA network recorded 188 fire-related exceedances of 1-hr and 24-hr Alberta Ambient Air Quality Objectives. Two air monitoring sites within Fort McMurray recorded mean/maximum 1-hr PM2.5 concentrations of 291/5229μgm-3 (AMS-6) and 293/3259μgm-3 (AMS-7) during fire impact periods. High correlations (r2=0.83-0.97) between biomass combustion related gases (carbon monoxide (CO), non-methane hydrocarbons (NMHC), total hydrocarbons (THC), total reduced sulfur (TRS), ammonia) and PM2.5 were observed at the sites. Filter-based 24-hr integrated PM2.5 samples collected every 6 days showed maximum concentrations of 267μgm-3 (AMS-6) and 394μgm-3 (AMS-7). Normalized excess emission ratios relative to CO were 149.87±3.37μgm-3ppm-1 (PM2.5), 0.274±0.002ppmppm-1 (THC), 0.169±0.001ppmppm-1 (NMHC), 0.104±0.001ppmppm-1 (CH4), 0.694±0.007ppbppm-1 (TRS), 0.519±0.040ppbppm-1 (SO2), 0.412±0.045ppbppm-1 (NO), 1.968±0.053ppbppm-1 (NO2), and 2.337±0.077ppbppm-1 (NOX). A subset of PM2.5 filter samples was analyzed for trace elements, major ions, organic carbon, elemental carbon, and carbohydrates. Sample mass reconstruction and fire specific emission profiles are presented and discussed. Potential fire-related photometric ozone instrument positive interferences were observed and were positively correlated with NO and NMHC.

A trivalent Apx-fusion protein delivered by E. coli outer membrane vesicles induce protection against Actinobacillus pleuropneumoniae of serotype 1 and 7 challenge in a murine model

Actinobacillus pleuropneumoniae (APP) causes serious economic losses in the swine industry, and is the etiologic agent of porcine pleuropneumonia. In this study we have engineered a trivalent Apx fusion protein enclosed in outer membrane vesicles (Apxr-OMV) and studied its immunoprotective efficacy against APP serotypes 1 and 7 challenge in mice. The results showed that the IgG levels in the Apxr-OMVs immune group were significantly higher than those of the negative control (P < 0.05). Up-regulation of both Th1 (IFN-γ, IL-2) and Th2 (IL-4) cytokines were detected in splenocytes of Apxr-OMVs immune group. The survival rates 87.5% and 62.5% were observed against APP strain 1516 of serotype 7 and APP strain 2701 of serotype 1 in the groups of Apxr-OMVs immune group, respectively. Histopathological lesions of the pulmonary structure alveoli were found to be minimal in APX-OMV group challenged with APP serotypes 1 and 7. These results strongly indicated that engineered OMVs could effectively induce specific humoral or cellular immune responses. Moreover, Apxr-OMVs used as novel vaccine provides cross-protective immunity against different serotype 1 and 7 of APP infection in a mouse model. In contrast, the OMV-empty and PBS as negative controls or inactivated strain of APP-2701 and APP-1516 as positive controls for the animal study cannot provide protection or cross-protection.

Response Characterization of an Inexpensive Aerosol Sensor

Inexpensive aerosol sensors have been considered as a complementary option to address the issue of expensive but low spatial coverage air quality monitoring networks. However, the accuracy and response characteristics of these sensors is poorly documented. In this study, inexpensive Shinyei PPD42NS and PPD60PV sensors were evaluated using a novel laboratory evaluation method. A continuously changing monodisperse size distribution of particles was generated using a Vibrating Orifice Aerosol Generator. Furthermore, the laboratory results were validated in a field experiment. The laboratory tests showed that both of the sensors responded to particulate mass (PM) concentration stimulus, rather than number concentration. The highest detection efficiency for the PPD42NS was within particle size range of 2.5-4 µm, and the respective optimal size range for the PPD60PV was 0.7-1 µm. The field test yielded high PM correlations (R² = 0.962 and R² = 0.986) for viable detection ranges of 1.6-5 and 0.3-1.6 µm, when compared to a medium cost optical dust monitor. As the size distribution of atmospheric particles tends to be bimodal, it is likely that indicatively valid results could be obtained for the PM10-2.5 size fraction (particulate mass in size range 2.5-10 µm) with the PPD42NS sensor. Respectively, the PPD60PV could possibly be used to measure the PM2.5 size fraction (particulate mass in size below 2.5 µm).

PM2.5 components and outpatient visits for asthma: A time-stratified case-crossover study in a suburban area

The effects of fine particles (PM_2.5) on asthma have been widely confirmed by epidemiological research studies. However, a limited number of studies have investigated the relationship between exposure to different PM_2.5 components and asthma. We characterized the PM_2.5 components in a suburban site of central Taiwan and conducted a time-stratified case-crossover study to elaborate the effects of daily concentration of each PM_2.5 component on asthma outpatient visits. We retrieved asthma outpatient claims for individuals less than 20 years old with a residential address in the Shalu district, Taiwan, from the National Health Insurance Research Database during 2000-2010. Multiple linear regression models were used to back extrapolate the historic concentration of individual components of PM_2.5 from 2000 through to 2010, including black carbon (BC) and eight ions, namely, sulfate, nitrate (NO₃^-), ammonium, chloride, potassium (K⁺), magnesium, calcium, sodium. The odds ratio (OR) with a 95% confidence interval (CI) of individual PM_2.5 components on asthma was estimated by conditional logistic regression. A total of 887 asthma outpatient visits with individuals who have an average age of 7.96±3.88 years were selected. After adjusting for confounders, we found an interquartile range (IQR) increase in BC level, an IQR increase in NO₃^- level, and an IQR increase in K⁺ level that were all associated with the increased risk of asthma outpatient visits from the current day (OR = 1.18, 95% CI: 1.05-1.34; OR = 1.11, 95% CI: 1.01-1.21; and OR = 1.16, 95% CI: 1.04-1.30, respectively). The effects of these components on asthma were stronger in the cold season than in the warm season. However, we did not find any lagging effects. The results suggest that exposure to NO₃^-, BC, and K⁺ derived from industry-related combustion or motor vehicles emission sources may increase the risk of asthma outpatient visits, particularly during the cold season.

Wildfire smoke exposure and human health: Significant gaps in research for a growing public health issue

Understanding the effect of wildfire smoke exposure on human health represents a unique interdisciplinary challenge to the scientific community. Population health studies indicate that wildfire smoke is a risk to human health and increases the healthcare burden of smoke-impacted areas. However, wildfire smoke composition is complex and dynamic, making characterization and modeling difficult. Furthermore, current efforts to study the effect of wildfire smoke are limited by availability of air quality measures and inconsistent air quality reporting among researchers. To help address these issues, we conducted a substantive review of wildfire smoke effects on population health, wildfire smoke exposure in occupational health, and experimental wood smoke exposure. Our goal was to evaluate the current literature on wildfire smoke and highlight important gaps in research. In particular we emphasize long-term health effects of wildfire smoke, recovery following wildfire smoke exposure, and health consequences of exposure in children.

Review of the health effects of wildland fire smoke on wildland firefighters and the public

Each year, the general public and wildland firefighters in the US are exposed to smoke from wildland fires. As part of an effort to characterize health risks of breathing this smoke, a review of the literature was conducted using five major databases, including PubMed and MEDLINE Web of Knowledge, to identify smoke components that present the highest hazard potential, the mechanisms of toxicity, review epidemiological studies for health effects and identify the current gap in knowledge on the health impacts of wildland fire smoke exposure. Respiratory events measured in time series studies as incidences of disease-caused mortality, hospital admissions, emergency room visits and symptoms in asthma and chronic obstructive pulmonary disease patients are the health effects that are most commonly associated with community level exposure to wildland fire smoke. A few recent studies have also determined associations between acute wildland fire smoke exposure and cardiovascular health end-points. These cardiopulmonary effects were mostly observed in association with ambient air concentrations of fine particulate matter (PM2.5). However, research on the health effects of this mixture is currently limited. The health effects of acute exposures beyond susceptible populations and the effects of chronic exposures experienced by the wildland firefighter are largely unknown. Longitudinal studies of wildland firefighters during and/or after the firefighting career could help elucidate some of the unknown health impacts of cumulative exposure to wildland fire smoke, establish occupational exposure limits and help determine the types of exposure controls that may be applicable to the occupation.

Employing Escherichia coli-derived outer membrane vesicles as an antigen delivery platform elicits protective immunity against Acinetobacter baumannii infection

Outer membrane vesicles (OMVs) have proven to be highly immunogenic and induced an immune response against bacterial infection in human clinics and animal models. We sought to investigate whether engineered OMVs can be a feasible antigen-delivery platform for efficiently inducing specific antibody responses. In this study, Omp22 (an outer membrane protein of A. baumannii) was displayed on E. coli DH5α-derived OMVs (Omp22-OMVs) using recombinant gene technology. The morphological features of Omp22-OMVs were similar to those of wild-type OMVs (wtOMVs). Immunization with Omp22-OMVs induced high titers of Omp22-specific antibodies. In a murine sepsis model, Omp22-OMV immunization significantly protected mice from lethal challenge with a clinically isolated A. baumannii strain, which was evidenced by the increased survival rate of the mice, the reduced bacterial burdens in the lung, spleen, liver, kidney, and blood, and the suppressed serum levels of inflammatory cytokines. In vitro opsonophagocytosis assays showed that antiserum collected from Omp22-OMV-immunized mice had bactericidal activity against clinical isolates, which was partly specific antibody-dependent. These results strongly indicated that engineered OMVs could display a whole heterologous protein (~22 kDa) on the surface and effectively induce specific antibody responses, and thus OMVs have the potential to be a feasible vaccine platform.

Episodic Impacts from California Wildfires Identified in Las Vegas Near-Road Air Quality Monitoring

Air pollutant concentrations near major highways are usually attributed to a combination of nearby traffic emissions and regional background, and generally presumed to be additive in nature. During a near-road measurement study conducted in Las Vegas, NV, the effects of distant wildfires on regional air quality were indicated over a several day period in the summer of 2009. Area-wide elevated particulate levoglucosan (maximum of 0.83 μg/m(3)) and roadside measurements of ultraviolet light-absorbing particulate matter (UVPM) in comparison to black carbon (Delta-C) were apparent over the three-day period. Back-trajectory modeling and satellite images supported the measurement results and indicated the transport of air pollutants from wildfires burning in southern California. Separating roadside measurements under apparent biomass burning event (Delta-C > 1000 ng m(-3)) and nonevent (Delta-C < 1000 ng m(-3)) periods, and constraining to specific days of week, wind speed range, wind direction from the road and traffic volume range, roadside carbon monoxide, black carbon, total particle number count (20-200 nm), and accumulation mode particle number count (100-200 nm) increased by 65%, 146%, 58%, and 366%, respectively, when biomass smoke was indicated. Meanwhile, ultrafine particles (20-100 nm) decreased by 35%. This episode indicates that the presence of aged wildfire smoke may interact with freshly emitted ultrafine particles, resulting in a decrease of particles in the ultrafine mode.

The impact of infield biomass burning on PM levels and its chemical composition

In the South of Italy, it is common for farmers to burn pruning waste from olive trees in spring. In order to evaluate the impact of the biomass burning source on the physical and chemical characteristics of the particulate matter (PM) emitted by these fires, a PM monitoring campaign was carried out in an olive grove. Daily PM10 samples were collected for 1 week, when there were no open fires, and when biomass was being burned, and at two different distances from the fires. Moreover, an optical particle counter and a polycyclic aromatic hydrocarbon (PAH) analyzer were used to measure the high time-resolved dimensional distribution of particles emitted and total PAHs concentrations, respectively. Chemical analysis of PM10 samples identified organic and inorganic components such as PAHs, ions, elements, and carbonaceous fractions (OC, EC). Analysis of the collected data showed the usefulness of organic and inorganic tracer species and of PAH diagnostic ratios for interpreting the impact of biomass fires on PM levels and on its chemical composition. Finally, high time-resolved monitoring of particle numbers and PAH concentrations was performed before, during, and after biomass burning, and these concentrations were seen to be very dependent on factors such as weather conditions, combustion efficiency, and temperature (smoldering versus flaming conditions), and moisture content of the wood burned.

Non-accidental health impacts of wildfire smoke

Wildfires take a heavy toll on human health worldwide. Climate change may increase the risk of wildfire frequency. Therefore, in view of adapted preventive actions, there is an urgent need to further understand the health effects and public awareness of wildfires. We conducted a systematic review of non-accidental health impacts of wildfire and incorporated lessons learned from recent experiences. Based on the literature, various studies have established the relationship between one of the major components of wildfire, particulate matter (particles with diameter less than 10 µm (PM10) and less than 2.5 µm (PM2.5)) and cardiorespiratory symptoms in terms of Emergency Rooms visits and hospital admissions. Associations between wildfire emissions and various subclinical effects have also been established. However, few relationships between wildfire emissions and mortality have been observed. Certain segments of the population may be particularly vulnerable to smoke-related health risks. Among them, people with pre-existing cardiopulmonary conditions, the elderly, smokers and, for professional reasons, firefighters. Potential action mechanisms have been highlighted. Overall, more research is needed to better understand health impact of wildfire exposure.

Downwind O3 and PM2.5 speciation during the wildfires in 2002 and 2010

A series of wildfires in northern Quebec, early July 2002, and in southern Quebec, late May 2010, resulted in severe air pollution downwind. Downwind exposures were investigated to estimate the impact on outdoor and indoor environments. The plumes derived from the wildfires resulted in an increase of over 10 ppbv ozone (O3) concentrations in both major cities and rural areas, while O3 enhancement was not observed at locations adjacent to wildfire burning areas. Temporal trend in PM2.5 concentration showed a peak of 105.5 μg/m3 on July 7, 2002, while on May 31, 2010 the peak was 151.1 μg/m3 in Boston downwind. PM2.5 speciation showed similar trends between the episodes, along with spikes in the PM2.5/PM10 ratio, and in the concentrations of Black Carbon, ΔC (i.e., UV absorbing compounds minus Black Carbon), Organic Carbon (OC), potassium, and chlorine. OC was the most dominant constituent of the PM2.5 mass in the wildfires. The dominant specific carbon fractions include OC fraction 3, pyrolysis carbon, and EC fraction 1, likely due to pyrolysis of structural components of wood. Indoor PM2.5 peaks at two houses corresponded well with the ambient PM2.5 peak, along with the elemental composition, which could indicate an impact of wildfires on indoor air pollution exposure.

Microorganisms associated particulate matter: a preliminary study

This study aims to determine the microbiological quality of particulate matter (PM) in an urban area in Jeddah, Saudi Arabia, during December 2012 to April 2013. This was achieved by the determination of airborne bacteria, fungi, and actinobacteria associated PM10 and PM2.5, as well as their relationships with gaseous pollutants, O3, SO2 and NO2, and meteorological factors (T°C, RH% and Ws). High volume samplers with PM10 and PM2.5 selective sizes, and glass fiber filters were used to collect PM10 and PM2.5, respectively. The filters were suspended in buffer phosphate and aliquots were spread plated onto the surfaces of trypticase soy agar, malt extract agar, and starch casein agar media for counting of bacteria, fungi and actinobacteria-associated PM, respectively. PM10 and PM2.5 concentrations averaged 159.9 μg/m(3) and 60 μg/m(3), respectively, with the ratio of PM2.5/PM10 averaged ~0.4. The concentrations of O3, SO2 and NO2 averaged 35.73 μg/m(3), 38.1μg/m(3) and 52.5 μg/m(3), respectively. Fungi and actinobacteria associated PM were found in lower concentrations than bacteria. The sum of microbial loads was higher in PM10 than PM2.5, however a significant correlation (r=0.57, P ≤ 0.05) was found between the sum of microbial loads associated PM10 and PM2.5. Aspergillus fumigatus and Aspergillus niger were the common fungal types associated PM. Temperature significantly correlated with both PM10 (r=0.44), and PM2.5 (r=0.5). Significant negative correlations were found between O3 and PM2.5 (r=-0.47), and between SO2 with PM10 (r=-0.48). Wind speed positively correlated with airborne microorganisms associated PM. The regression model showed that the inverse PM2.5 concentration (1/PM2.5) was a significant determinant of fungal count associated PM. Chemical processes and environmental factors could affect properties of PM and in turn its biological quality.

Effects of Siberian wildfires on the chemical composition and acidity of atmospheric aerosols of remote urban, rural and background territories

Extensive forest fires occurred during the summer of 2012 in Siberia. This work presents the influence of long-range atmospheric smoke on the aerosol properties at urban, suburban and background sites, which are located 400-800 km from the fire source. The higher levels of submicron particles (PM1), organic (OC), secondary organic (SOC) and elemental (EC) carbon were observed at all sampling sites, whereas an increase in ionic species HCOO(-), K(+), NO3(-), and Cl(-) and a decrease in pH was higher at the background and suburban sites in comparison with the urban site. Other natural and anthropogenic factors appear to be more significant for ions Ca(2+) + Mg(2+), HCO3(-), NH4(+), SO4(2-) and Na(+). The present study indicates that the impact of remote fires on the aerosol characteristics depends on their background (without fires) levels at the sampling sites.

Seasonal variations in the chemical composition of particulate matter: a case study in the Po Valley. Part II: concentration and solubility of micro- and trace-elements

Size distribution (fine and coarse fraction) and solubility distribution (extracted and residual fraction) of 20 elements (As, Ba, Be, Cd, Co, Cu, Fe, Li, Mn, Pb, Ni, Rb, S, Sb, Se, Sn, Sr, Ti, Tl, V) in atmospheric particulate matter (PM) were determined during a 5-year field study carried out in the Po Valley (peri-urban area of Ferrara, in Northern Italy). By studying the contribution of the two size fractions and the two solubility fractions to the atmospheric concentration of each element, it was possible to obtain interesting information about the variability of PM sources, to assess the role played by atmospheric stability in determining pollution episodes, and to obtain an estimate of the bio-accessible fraction. Atmospheric stability is confirmed to be one of the main causes of atmospheric pollution in this area and is to be responsible for the pronounced winter increase in both PM and elemental concentration. Long-range transport of natural and polluted air masses caused temporary increases in PM and elemental concentration, while local industrial emission seemed to play a secondary role. Regulated elements were well below their concentration limit, but many toxic elements were in the form of fine particles and soluble chemical species, more accessible to the environment, and the human body.

Physicochemical and toxicological characteristics of urban aerosols during a recent Indonesian biomass burning episode

Air particulate matter (PM) samples were collected in Singapore from 21 to 29 October 2010. During this time period, a severe regional smoke haze episode lasted for a few days (21-23 October). Physicochemical and toxicological characteristics of both haze and non-haze aerosols were evaluated. The average mass concentration of PM2.5 (PM with aerodynamic diameter of ≤2.5 μm) increased by a factor of 4 during the smoke haze period (107.2 μg/m(3)) as compared to that during the non-smoke haze period (27.0 μg/m(3)). The PM2.5 samples were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency and 10 transition metals. Out of the seven PAHs known as potential or suspected carcinogens, five were found in significantly higher levels in smoke haze aerosols as compared to those in the background air. Metal concentrations were also found to be higher in haze aerosols. Additionally, the toxicological profile of the PM2.5 samples was evaluated using a human epithelial lung cell line (A549). Cell viability and death counts were measured after a direct exposure of PM2.5 samples to A459 cells for a period of 48 h. The percentage of metabolically active cells decreased significantly following a direct exposure to PM samples collected during the haze period. To provide further insights into the toxicological characteristics of the aerosol particles, glutathione levels, as an indirect measure of oxidative stress and caspase-3/7 levels as a measure of apoptotic death, were also evaluated.

Toxicity and elemental composition of particulate matter from outdoor and indoor air of elementary schools in Munich, Germany

Outdoor particulate matter (PM(10)) is associated with detrimental health effects. However, individual PM(10) exposure occurs mostly indoors. We therefore compared the toxic effects of classroom, outdoor, and residential PM(10). Indoor and outdoor PM(10) was collected from six schools in Munich during teaching hours and in six homes. Particles were analyzed by scanning electron microscopy and X-ray spectroscopy (EDX). Toxicity was evaluated in human primary keratinocytes, lung epithelial cells and after metabolic activation by several human cytochromes P450. We found that PM(10) concentrations during teaching hours were 5.6-times higher than outdoors (117 ± 48 μg/m(3) vs. 21 ± 15 μg/m(3), P < 0.001). Compared to outdoors, indoor PM contained more silicate (36% of particle number), organic (29%, probably originating from human skin), and Ca-carbonate particles (12%, probably originating from paper). Outdoor PM contained more Ca-sulfate particles (38%). Indoor PM at 6 μg/cm(2) (10 μg/ml) caused toxicity in keratinocytes and in cells expressing CYP2B6 and CYP3A4. Toxicity by CYP2B6 was abolished with the reactive oxygen species scavenger N-acetylcysteine. We concluded that outdoor PM(10) and indoor PM(10) from homes were devoid of toxicity. Indoor PM(10) was elevated, chemically different and toxicologically more active than outdoor PM(10). Whether the effects translate into a significant health risk needs to be determined. Until then, we suggest better ventilation as a sensible option.

PRACTICAL IMPLICATIONS

Indoor air PM(10) on an equal weight base is toxicologically more active than outdoor PM(10). In addition, indoor PM(10) concentrations are about six times higher than outdoor air. Thus, ventilation of classrooms with outdoor air will improve air quality and is likely to provide a health benefit. It is also easier than cleaning PM(10) from indoor air, which has proven to be tedious.

Chemical composition of fine particles in fresh smoke plumes from boreal wild-land fires in Europe

A series of smoke plumes was detected in Helsinki, Finland, during a one-month-lasting period in August 2006. The smoke plumes originated from wildfires close to Finland, and they were short-term and had a high particulate matter (PM) concentration. Physical and chemical properties of fine particles in those smokes were characterised by a wide range of real-time measurements that enabled the examination of individual plume events. Concurrently PM(1) filter samples were collected and analysed off-line. Satellite observations employing MODIS sensor on board of NASA EOS Terra satellite with the dispersion model SILAM and the Fire Assimilation System were used for evaluation of the emission fluxes from wildfires. The model predicted well the timing of the plumes but the predicted PM concentrations differed from the observed. The measurements showed that the major growth in PM concentration was caused by submicrometer particles consisting mainly of particulate organic matter (POM). POM had not totally oxidised during the transport based on the low WSOC-to-OC ratio. The fresh plumes were compared to another major smoke episode that was observed in Helsinki during April-May 2006. The duration and the source areas of the two episode periods differed. The episode in April-May was a period of nearly constantly upraised level of long-range transported PM and it was composed of aged particles when arriving in Helsinki. The two episodes had differences also in the chemical composition of PM. The mass concentrations of biomass burning tracers (levoglucosan, potassium, and oxalate) increased during both the episodes but different concentration levels of elemental carbon and potassium indicated that the episodes differed in the form of burning as well as in the burning material. In spring dry crop residue and hay from the previous season were burnt whereas in August smokes from smouldering and incomplete burning of fresh vegetation were detected.

Seasonal variation in chemical composition of size-segregated urban air particles and the inflammatory activity in the mouse lung

We investigated the seasonal variations in the chemical composition and in vivo inflammatory activity of urban air particulate samples in four size ranges (PM(10-2.5), PM(2.5-1), PM(1-0.2), and PM(0.2)). The samples were collected in Helsinki using a high-volume cascade impactor (HVCI). Healthy C57BL/6J mice were intratracheally instilled with a single dose (10 mg/kg) of the particulate samples. The lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6, and keratinocyte-derived chemokine [KC]) at 4 h, and total cell number and total protein concentration at 12 h. The PM(10-2.5) and PM(2.5-1) samples had much higher inflammatory potency than the PM(1-0.2) and PM(0.2) samples. The relative inflammatory activities of the autumn samples were the highest on an equal mass basis, but when estimated for the particulate mass per cubic meter of air, the springtime samples had the highest inflammatory potential. Resuspended soil material and other non-exhaust particulate material from traffic were associated with a high inflammatory activity of the PM(10-2.5) and PM(2.5-1) samples. Secondary inorganic ions in the PM(1-0.2) and PM(0.2) samples had inconsistent negative or positive correlations with the inflammatory activity. There were no systematic seasonal variations in the tracers of incomplete combustion and atmospherically oxidized organics in the PM(1-0.2) and PM(0.2) samples, which probably explains their low correlations with the inflammatory activity. In conclusion, in a relatively clean Nordic city, the resuspension of road dust and other non-exhaust particulate material from traffic were the major sources of inflammatory activity of urban air inhalable particles.

Characterization and origin of EC and OC particulate matter near the Doñana National Park (SW Spain)

In the South of Spain, major industrial estates (e.g. Huelva) exist alongside ecologically interesting zones (e.g. Doñana National Park). Between June 2005 and June 2006, PM10 and PM2.5 were measured, for total mass, organic carbon (OC) and elemental carbon (EC) chemical composition, at a station in an ecologically interesting area located near Doñana National Park and an urban background area with industrial influence. The mean OC concentration is higher in the urban background (3.5 microg m(-3)) than in the rural monitoring station (2.8 microg m(-3)) as a consequence of local emissions (e.g. traffic). A total of 82% of TC is OC in the rural station, while the urban background station reveals 70% and 73% of TC in the PM10 and PM2.5 mass, respectively. The study of air-mass origin and characterization of carbonaceous species in the course of simultaneous sampling in rural and urban background monitoring stations differentiated three long-range air-mass transports: a North-African dust outbreak, Atlantic Advection and Continental (N-NW) episodes, the origins of the first and last of which are more heavily influenced by the anthropogenic emissions from industrial estates located around the city of Huelva (Punta del Sebo and Nuevo Puerto). Higher values were measured for OC and EC in the study area during the North-African dust outbreak, similar to those obtained during the Continental episode (N-NW), which was clearly influenced by industrial emissions, followed by the Atlantic Advection episodes. The comparison of carbon species with air-mass origin can help to discriminate the origin and source of particulate matter, as well as to determine the urban impact on rural areas.

Population exposure to fine particles and estimated excess mortality in Finland from an East European wildfire episode

Long-range transported particulate matter (PM) air pollution episodes associated with wildfires in the Eastern Europe are relatively common in Southern and Southeastern Finland. In severe cases such as in August-September 2002, the reduced visibility and smell of the smoke, and symptoms such as irritation of eyes and airways experienced by the population raise the issue into the headlines. Because PM air pollution, in general, has been identified as a major health risk, and the exposures are of repeating nature, the issue warrants a risk assessment to estimate the magnitude of the problem. The current work uses the available air quality data in Finland to estimate population exposures caused by one of the worst episodes experienced in this decade. This episode originated from wildfires in Russia, Belarus, Ukraine, and the Baltic countries. The populations of 11 Southern Finnish provinces were exposed between 26 August and 8 September 2002, for 2 weeks to an additional population-weighted average PM(2.5) level of 15.7 microg/m(3). Assuming similar effect on mortality for these particles as observed in epidemiological time series studies on urban particles (0.5%-2% increase in mortality per 10 microg/m(3), central estimate 1%), this exposure level would be associated with 9-34 cases (17 cases central estimate) of additional mortality. Epidemiological evidence specific to particles from biomass combustion is scarce, affecting also the reliability of the current risk assessment. Do the wildfire aerosols exhibit the same level of toxicity as the urban particles? To shed light on this question, it is interesting to look at the exposure data in relationship to the observed daily mortality in Finland, even though the limited duration of the episode allows only for a weak statistical power. The percentage increases observed (0.8%-2.1% per 10 microg/m(3) of fine PM) are in line with the more general estimates for urban PM and those used in the current risk assessment.

Measurements of oxalic acid, oxalates, malonic acid, and malonates in atmospheric particulates

This study systematically examined effects of analytical approaches on resultant concentrations of oxalic acid, oxalates, malonic acid, and malonates. Results demonstrated that employing separate water extraction and THF extraction is required to properly quantify dicarboxylic acids vs dicarboxylates using IC or GC-MS. Applications of the recommended methods to analyze PM2.5 collected in Singapore showed that concentrations of oxalate ranged from 361.4 to 481.4 ng m(-3), which were 10-14.7 times higher than that of oxalic acid. Unlike that of oxalates, malonate concentrations (10.5-23.4 ng m(-3)) were no more than half of malonic acid concentration (43.8-53.9 ng m(-3)) in PM2.5. Concentration ratios of oxalate-to-oxalic acid and malonate-to-malonic acid obtained from this work were applied to reported literature data; as a first approximation, in urban environments similar to that in Singapore, quantifiable oxalic acid, oxalates, malonic acid, and malonates in PM2.5 could range from 7.6 to 68.0, 82.2 to 732.8, 6.3 to 150, and 1.3 to 60 ng m(-3), respectively. Because photooxidation properties and hygroscopicity of dicarboxylic acids can substantially differ from that of dicarboxylates, more studies are needed to quantify ambient oxalic acid and malonic acid vs oxalates and malonates.

Fate and transport of emissions for several trace metals over the United States

A regional model for atmospheric photochemistry and particulate matter is used to predict the fate and transport of five trace metals: lead, manganese, total chromium, nickel, and cadmium over the continental United States during January and July 2001. Predicted concentrations of the metals are compared to observations. Lead predictions have the lowest mean differences with observations and the highest correlation coefficients. They best agree with observations made in January over residential and commercial areas in the eastern United States and worst with observations over remote forests and deserts located in the western United States during July. Manganese predictions show similar abilities to reproduce observations but had larger changes between months. Chromium and nickel predictions show diminishing ability to reproduce observations over both urban and rural areas. Cadmium predictions show the least ability to reproduce observations. Potential causes are examined for the errors in predictions. For errors in lead, manganese and perhaps chromium predictions, aerial suspension and biomass burning are suspected because simulations did not include emissions from these sources. Nickel, cadmium and, to a lower extent, chromium predictions suffer from errors in the emissions that represent current anthropogenic activities. Predicted concentrations of all metals show errors from not including sub-grid processes in meteorological and emission rates. Examples include sea breeze circulation along coastal areas and individual sources in urban areas. These errors reduce the ability to reproduce the time dependence of observations.

The health impact of common inorganic components of fine particulate matter (PM2.5) in ambient air: a critical review

Ambient air particulate matter (PM) originates as either primary particles emitted directly into the atmosphere from a specific source or as secondary particles produced from atmospheric chemical reactions between precursor gases or between these gases and primary particles. PM can derive from both natural and anthropogenic sources, resulting in a complex chemical mix. The "fine" size mode of ambient PM, designated as PM(2.5), is defined as comprising those particles having aerodynamic diameters below 2.5 microm. While the total mass of PM(2.5) has been associated with adverse human health outcomes, the relationship between these and specific chemical components has not been resolved. This article provides a perspective on the current state of the science concerning health effects from a major group of chemical species found within PM(2.5), namely common inorganic constituents. The specific chemical classes discussed herein are secondary inorganic species, namely, sulfate, nitrate, and acidity, and generally crustal-derived species, namely, phosphate, sodium, potassium, calcium, magnesium, silicon, and aluminum. The article discusses evidence for adverse health effects from inorganic PM(2.5) components within the framework of various caveats surrounding both epidemiology and toxicology assessments. The largest database exists for sulfate, but conclusions that attribute sulfate to health outcomes have not been consistent across all epidemiology studies, and there is a lack of coherence with toxicology studies, which show biological responses only at high levels of exposure. Limited epidemiological and toxicological data for nitrate suggests little or no adverse health effects at current levels. Epidemiological studies specifically identifying crustal components of PM(2.5) suggest that they are not likely, by themselves, to produce a significant health risk, and these components do not have unequivocal biological plausibility from toxicological studies for being significant contributors to adverse health outcomes.

In vitro inflammatory and cytotoxic effects of size-segregated particulate samples collected during long-range transport of wildfire smoke to Helsinki

The impact of long-range transport (LRT) episodes of wildfire smoke on the inflammogenic and cytotoxic activity of urban air particles was investigated in the mouse RAW 264.7 macrophages. The particles were sampled in four size ranges using a modified Harvard high-volume cascade impactor, and the samples were chemically characterized for identification of different emission sources. The particulate mass concentration in the accumulation size range (PM(1-0.2)) was highly increased during two LRT episodes, but the contents of total and genotoxic polycyclic aromatic hydrocarbons (PAH) in collected particulate samples were only 10-25% of those in the seasonal average sample. The ability of coarse (PM(10-2.5)), intermodal size range (PM(2.5-1)), PM(1-0.2) and ultrafine (PM(0.2)) particles to cause cytokine production (TNFalpha, IL-6, MIP-2) reduced along with smaller particle size, but the size range had a much smaller impact on induced nitric oxide (NO) production and cytotoxicity or apoptosis. The aerosol particles collected during LRT episodes had a substantially lower activity in cytokine production than the corresponding particles of the seasonal average period, which is suggested to be due to chemical transformation of the organic fraction during aging. However, the episode events were associated with enhanced inflammogenic and cytotoxic activities per inhaled cubic meter of air due to the greatly increased particulate mass concentration in the accumulation size range, which may have public health implications.