Wood smoke as a source of particle-phase organic compounds in residential areas

The objective of this study was to investigate the organic composition of wood smoke emissions and ambient air samples in order to determine the wood smoke contribution to the ambient air pollution in the residential areas. From November 2005 to March 2006 particle-phase PM₁₀ samples were collected in the residential town Dettenhausen surrounded by forests near Stuttgart in southern Germany. Samples collected on pre-baked glass fibre filters were extracted using toluene with ultrasonic bath and analysed by gas chromatography mass spectrometry (GC-MS). 21 polycyclic aromatic hydrocarbons (PAH) including 16 USEPA priority pollutants, different organic wood smoke tracers, primarily 21 species of syringol and guaiacol derivatives, levoglucosan and its isomers mannosan, galactosan and dehydroabietic acid were detected and quantified in this study. The concentrations of these compounds were compared with the fingerprints of emissions from hardwood and softwood combustion carried out in test facilities at Universitaet Stuttgart and field investigations at a wood stove during real operation in Dettenhausen. It was observed that the combustion derived PAH was detected in higher concentrations than other PAH in the ambient air PM₁₀ samples. Syringol and its derivatives were found in large amounts in hardwood burning but were not detected in softwood burning emissions. On the other hand, guaiacol and its derivatives were found in both softwood and hardwood burning emissions, but the concentrations were higher in the softwood smoke compared to hardwood smoke. So, these compounds can be used as typical tracer compounds for the different types of wood burning emissions. In ambient air samples both syringol and guaiacol derivatives were found which indicates the wood combustion contribution to the PM load in such residential areas. Levoglucosan was detected in high concentrations in all ambient PM₁₀ samples. A source apportionment modelling, Positive Matrix Factorization (PMF) was implemented to quantify the wood smoke contribution to the ambient PM₁₀ bound organic compounds in the residential area.     

Seasonal distribution of polar organic compounds in the urban atmosphere of two large cities from the North and South of Europe

Polar organic species, including n-alkanols, sterols, anhydrosugars, n-alkanoic acids, n-alkenoic acids and dicarboxylic acids were quantified to typify the composition of fine (PM_2.5) and coarse (PM_10–2.5) aerosols collected simultaneously at roadside and background sites in Oporto (Portugal) and Copenhagen (Denmark) during separate month-long intensive summer and winter campaigns. As a general trend, both cities exhibit roadside average concentrations higher than their correspondent urban background levels. The polar organics are more abundant in the fine fraction, exhibiting a seasonal pattern with high winter concentrations and low summer loads. Aerosols from both cities showed typical distributions of n-alkanols and n-alkanoic acids in the ranges C₁₂–C₂₈ and C₈–C₂₈, respectively. The <C₂₀ homologues, usually attributed to kitchen emissions, vehicular exhausts and microbial origins, dominated the fatty acid fraction. Linear alcohols were mainly represented by higher molecular weight homologues from vegetation waxes. Molecular tracer species for wood smoke (e.g. levoglucosan, mannosan and resinic acids) were found to contribute significantly to the urban aerosol, especially in winter. Ratios between these tracers indicated different biofuel contributions to the atmospheric particles of the two cities. Secondary constituents from both biogenic (e.g. pinonic acid) and anthropogenic precursors (e.g. phthalic and benzoic acids) were detected in both cities and seasons.     

Comprehensive primary particulate organic characterization of vehicular exhaust emissions in France

A study to characterize primary particulate matter (PM_2.5 and PM₁₀) from the French vehicular fleet was conducted during winter 2008, in a tunnel in Marseille, France. The carbonaceous fraction represents 70% of the aerosol mass and elemental carbon fraction (EC) represent 60% of the carbonaceous fraction. The organic carbon OC was characterized in term of its water soluble fraction, functionalization rate and HULIS content. Seventy trace organic compounds including alkanes, polycyclic aromatic hydrocarbons (PAH), petroleum biomarkers and carboxylic acids were also quantified, in order to determine an organic emission profile for chemical mass balance modeling studies. Such source profiles were still missing in Europe and particularly in France. The profile obtained in this study is consistent with profiles determined in tunnel or dynamometer studies performed in other countries during the last ten years. These results suggest that organic compounds profiles from vehicular exhaust emissions are not significantly influenced by the geographic area and are thus suitable for use in aerosol source apportionment modeling applied across extensive regions. The chemical profile determined here is very similar to those obtained for diesel emissions with high concentrations of EC relative to OC (EC/OC = 1.8) and low concentrations of the higher molecular weight PAH. These results are consistent with the high proportion of diesel vehicles in the French fleet (49%).     

Influence of tobacco smoke on carcinogenic PAH composition in indoor PM10 and PM2.5

Because of the mutagenic and/or carcinogenic properties, Polycyclic Aromatic Hydrocarbons (PAH), have a direct impact on human population. Consequently, there is a widespread interest in analysing and evaluating the exposure to PAH in different indoor environments, influenced by different emission sources. The information on indoor PAH is still limited, mainly in terms of PAH distribution in indoor particles of different sizes; thus, this study evaluated the influence of tobacco smoke on PM₁₀ and PM_2.5 characteristics, namely on their PAH compositions, with further aim to understand the negative impact of tobacco smoke on human health. Samples were collected at one site influenced by tobacco smoke and at one reference (non-smoking) site using low-volume samplers; the analyses of 17 PAH were performed by Microwave Assisted Extraction combined with Liquid Chromatography (MAE–LC). At the site influenced by tobacco smoke PM concentrations were higher 650% for PM₁₀, and 720% for PM_2.5. When influenced by smoking, 4 ring PAH (fluoranthene, pyrene, and chrysene) were the most abundant PAH, with concentrations 4600–21 000% and 5100–20 800% higher than at the reference site for PM₁₀ and PM_2.5, respectively, accounting for 49% of total PAH (Σ_PAH). Higher molecular weight PAH (5–6 rings) reached concentrations 300–1300% and 140–1700% higher for PM₁₀ and PM_2.5, respectively, at the site influenced by tobacco smoke. Considering 9 carcinogenic PAH this increase was 780% and 760% in PM₁₀ and PM_2.5, respectively, indicating the strong potential risk for human health. As different composition profiles of PAH in indoor PM were obtained for reference and smoking sites, those 9 carcinogens represented at the reference site 84% and 86% of Σ_PAH in PM₁₀ and PM_2.5, respectively, and at the smoking site 56% and 55% of Σ_PAH in PM₁₀ and PM_2.5, respectively. All PAH (including the carcinogenic ones) were mainly present in fine particles, which corresponds to a strong risk for cardiopulmonary disease and lung cancer; thus, these conclusions are relevant for the development of strategies to protect public health.     

Wood Smoke Contribution to Winter Aerosol in Fresno,CA

Abstract

In an effort to better quantify wintertime particulate matter (PM) and the contribution of wood smoke to air pollution events in Fresno, CA, a field campaign was conducted in winter 2003–2004. Coarse and fine daily PM samples were collected at five locations in Fresno, including residential, urban, and industrial areas. Measurements of collected samples included gravimetric mass determination, organic and elemental carbon analysis, and trace organic compound analysis by gas chromatograph mass spectrometry (GC/MS). The wood smoke tracer levoglucosan was also measured in aqueous aerosol extracts using high-performance anion exchange chromatography coupled with pulsed amperometric detection. Sample preparation and analysis by this technique is much simpler and less expensive than derivatized levoglucosan analysis by GC/MS, permitting analysis of daily PM samples from all five of the measurement locations. Analyses revealed low spatial variability and similar temporal patterns of PM_2.5 mass, organic carbon (OC), and levoglucosan. Daily mass concentrations appear to have been strongly influenced by meteorological conditions, including precipitation, wind, and fog events. Fine PM (PM_2.5) concentrations are uncommonly low during the study period, reflecting frequent precipitation events. During the first portion of the study, levoglucosan had a strong relationship to the concentrations of PM_2.5 and OC. In the later portion of the study, there was a significant reduction in levoglucosan relative to PM_2.5 and OC. This may indicate a change in particle removal processes, perhaps because of fog events, which were more common in the latter period. Combined, the emissions from wood smoke, meat cooking, and motor vehicles appear to contribute ~65–80% to measured OC, with wood smoke, on average, accounting for ~41% of OC and ~18% of PM_2.5 mass. Two residential sites exhibit somewhat higher contributions of wood smoke to OC than other locations.     

Particulate n-alkanes,n-alkanoic acids and polycyclic aromatic hydrocarbons in the atmosphere of Algiers City Area

The concentrations of particulate organic matter were measured from May to September 1998 in urban area of Algiers and in municipal waste landfill of Oued Smar. For the sake of comparability, organic aerosols were also monitored at Montelibretti (Italy) in June of the same year. In addition to n-alkanes and polycyclic aromatic hydrocarbons (PAH), monocarboxylic n-alkanoic acids accounted for a large portion of identified organic compounds of aerosol at both Algerian sites. All these species were more abundant at Oued Smar than in downtown Algiers. At the urban site, concentration levels reached by n-alkanes and PAH highlighted the strong impact of motor vehicle emission resulting over the city area. Instead, at the Oued Smar landfill n-alkane and PAH contents depended upon the nature and account of the wastes burnt, and their behaviours were consistent with a pyrolytic origin. n-Alkanoic acids rather originated from the bacterial activity. By contrast, n-alkanes and n-alkanoic acids at Montelibretti seemed to be released by biogenic sources, whereas PAH presence was related to downwind transport of air parcels from Rome metropolitan area.     

The Distribution of Particle-Phase Organic Compounds in the Atmosphere and Their Use for Source Apportionment during the Southern California Children’s Health Study

Abstract

Atmospheric particulate matter (PM) samples from 12 sites in southern California, collected as part of the Southern California Children’s Health Study (SCCHS), were analyzed using gas chromatography/mass spectrometry (GC/MS) techniques. Ninety-four organic compounds were quantified in these samples, including n-alkanes, fatty acids, polycyclic aromatic hydrocarbons (PAH), ho-panes, steranes, aromatic diacids, aliphatic diacids, resin acids, methoxyphenols, and levoglucosan. Annual average concentrations of all detected compounds, as well as average concentrations for three seasonal periods, were determined at all 12 sites for the calendar year of 1995. These measurements provide important information about the seasonal and spatial distribution of particle-phase organic compounds in southern California. Also, co-located samples from one site were analyzed to assess precision of measurement. Excellent agreement was observed between annual average concentrations for the broad range of organic compounds measured in this study. Measured concentrations from the 12 sampling sites were used in a previously developed molecular-marker source apportionment model to quantify the primary source contributions to the PM₁₀ organic carbon and mass concentrations at these 12 sites. Source contributions to atmospheric PM from six important air pollution sources were quantified: gasoline-powered motor vehicle exhaust, diesel vehicle exhaust, wood smoke, vegetative detritus, tire wear, and natural gas combustion. Important trends in the seasonal and spatial patterns of the impact of these six sources were observed. In addition, contributions from meat smoke were detected in selected samples.     

Wood burning impact on PM10 in three Austrian regions

Anhydrosugars (levoglucosan, mannosan and galactosan) were investigated during one year in three Austrian regions at three types of sites (city-heavy traffic-impacted, city-residential and background) in order to assess the magnitude of the contribution of wood smoke to the particulate matter load and its organic fraction. The annually averaged concentrations of levoglucosan ranged from 0.12 to 0.48 μg m^?3. The levoglucosan concentration exhibited a strong annual cycle with higher concentrations in the cold season. The minor anhydrosugars had a similar annual trend, but their concentrations were lower by a factor of about 5 and about 25 in the cold season for mannosan and galactosan, respectively. Levoglucosan concentrations were higher at the inner-urban as compared to rural sites. The contribution of wood smoke to organic carbon and PM₁₀ levels was calculated using a constant ratio of levoglucosan and OC, respectively PM₁₀ as derived for fire wood typical for Alpine European regions [Schmidl, C., Marr, I.L., Caseiro, A.e, Kotianová, P., Berner, A., Bauer, H., Kasper-Giebl, A., Puxbaum, H., 2008a. Chemical characterisation of fine particle emissions from wood stove combustion of common woods growing in mid-European Alpine regions. Atmospheric Environment 42, 126–141]. The estimated contribution of wood smoke-OC to the OC of PM₁₀ ranged from one third to more than half in the cold season with higher contributions up to 70% in winter (December, January and February) in the smaller cities and the rural background. This indicates, that wood smoke is the predominant source of organic material at rural and small urban sites in central Europe. Consistently, wood smoke was an important contributor to PM₁₀ during the cold season, with contributions of around 10% in the Vienna larger region and around 20% at rural sites in the densely forested regions of Salzburg and Styria during the winter months. In those regions residential sites exhibited highest relative wood smoke contents in PM₁₀ during autumn (September till November), indicating the use of wood stoves for auxiliary heating in the transition of warm to cold season. Using the relationships between the different anhydrosugars the combustion of softwood was found to be dominant for the wood smoke occurrence in ambient air at the investigated sites. Potassium, a commonly used tracer for biomass burning, correlated well to levoglucosan, with a mass ratio of around 0.80 in the cold season.     

The impact of wood stove technology upgrades on indoor residential air quality

Fine particulate matter (PM_2.5) air pollution has been linked to adverse health impacts, and combustion sources including residential wood-burning may play an important role in some regions. Recent evidence suggests that indoor air quality may improve in homes where older, non-certified wood stoves are exchanged for lower emissions EPA-certified alternatives. As part of a wood stove exchange program in northern British Columbia, Canada, we sampled outdoor and indoor air at 15 homes during 6-day sampling sessions both before and after non-certified wood stoves were exchanged. During each sampling session two consecutive 3-day PM_2.5 samples were collected onto Teflon filters, which were weighed and analyzed for the wood smoke tracer levoglucosan. Residential PM_2.5 infiltration efficiencies (F_inf) were estimated from continuous light scattering measurements made with nephelometers, and estimates of F_inf were used to calculate the outdoor- and indoor-generated contributions to indoor air. There was not a consistent relationship between stove technology and outdoor or indoor concentrations of PM_2.5 or levoglucosan. Mean F_inf estimates were low and similar during pre- and post-exchange periods (0.32 ± 0.17 and 0.33 ± 0.17, respectively). Indoor sources contributed the majority (～65%) of the indoor PM_2.5 concentrations, independent of stove technology, although low indoor-outdoor levoglucosan ratios (median ≤ 0.19) and low indoor PM_2.5-levoglucosan correlations (r ≤ 0.19) suggested that wood smoke was not a major indoor PM_2.5 source in most of these homes. In summary, despite the potential for extensive wood stove exchange programs to reduce outdoor PM_2.5 concentrations in wood smoke-impacted communities, we did not find a consistent relationship between stove technology upgrades and indoor air quality improvements in homes where stoves were exchanged.     

Particulate organic compounds emitted from experimental wildland fires in a Mediterranean ecosystem

Fine (PM_2.5) and coarse (PM_2.5–10) smoke particles from controlled biomass burnings of a shrub-dominated forest in Lousã Mountain, Portugal, enabled the quantification by chromatographic techniques of several molecular tracers for the combustion of Mediterranean forest ecosystems, which could be conducive to source apportionment studies. The major organic components in the smoke samples were pyrolysates of vegetation cuticles, mainly comprising steradienes and sterol derivatives, carbohydrates from the breakdown of cellulose, aliphatic lipids from vegetation waxes and methoxyphenols from the lignin thermal degradation. Most of these compounds are chiefly found in fine particles. Polycyclic aromatic hydrocarbons (PAH) were also present as minor constituents. Anhydrosugar and PAH molecular diagnostic ratios were applied as source assignment tools. Some biomarkers are reported for the first time in biomass burning smoke.     

Emission factors of particulate matter,polycyclic aromatic hydrocarbons,and levoglucosan from wood combustion in south-central Chile

In south-central Chile, wood stoves have been identified as an important source of air pollution in populated areas. Eucalyptus (Eucalyptus globulus), Chilean oak (Nothofagus oblique), and mimosa (Acacia dealbata) were burned in a single-chamber slow-combustion wood stove at a controlled testing facility located at the University of Concepción, Chile. In each experiment, 2.7–3.1 kg of firewood were combusted while continuously monitoring temperature, exhaust gases, burn rate, and collecting particulate matter samples in Teflon filters under isokinetic conditions for polycyclic aromatic hydrocarbon and levoglucosan analyses. Mean particulate matter emission factors were 2.03, 4.06, and 3.84 g/kg dry wood for eucalyptus, oak, and mimosa, respectively. The emission factors were inversely correlated with combustion efficiency. The mean emission factors of the sums of 12 polycyclic aromatic hydrocarbons in particle phases were 1472.5, 2134.0, and 747.5 μg/kg for eucalyptus, oak, and mimosa, respectively. Fluoranthene, pyrene, benzo[a]anthracene, and chrysene were present in the particle phase in higher proportions compared with other polycyclic aromatic hydrocarbons that were analyzed. Mean levoglucosan emission factors were 854.9, 202.3, and 328.0 mg/kg for eucalyptus, oak, and mimosa, respectively. Since the emissions of particulate matter and other pollutants were inversely correlated with combustion efficiency, implementing more efficient technologies would help to reduce air pollutant emissions from wood combustion.

Implications: Residential wood burning has been identified as a significant source of air pollution in populated areas. Local wood species are combusted for home cooking and heating, which releases several toxic air pollutants, including particulate matter, carbon monoxide, and polycyclic aromatic hydrocarbons. Air pollutant emissions depend on the type of wood and the technology and operational conditions of the wood stove. A better understanding of emissions from local wood species and wood stove performance would help to identify better biomass fuels and wood stove technologies in order to reduce air pollution from residential wood burning.     

Characterization of organic aerosol in Big Bend National Park,Texas

The Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study was conducted in Big Bend National Park, Texas, July through October 1999. Daily PM_2.5 organic aerosol samples were collected on pre-fired quartz fiber filters. Daily concentrations were too low for detailed organic analysis by gas chromatography-mass spectrometry (GC-MS) and were grouped based on their air mass trajectories. A total of 12 composites, each containing 3–10 daily samples, were analyzed. Alkane carbon preference indices suggest primary biogenic emissions were small contributors to primary PM_2.5 organic matter (OM) during the first 3 months, while in October air masses advecting from the north and south were more strongly influenced by biogenic sources. A series of trace organic compounds previously shown to serve as particle phase tracers for various carbonaceous aerosol source types were examined. Molecular tracer species were generally at or below detection limits, except for the wood smoke tracer levoglucosan in one composite, so maximum possible source influences were calculated using the detection limit as an upper bound to the tracer concentration. Wood smoke was found not to contribute significantly to PM_2.5 OM, with contributions for most samples at <1% of the total organic particulate matter. Vehicular exhaust also appeared to make only minor contributions, with maximum possible influences calculated to be 1–4% of PM_2.5 OM. Several factors indicate that secondary organic aerosol formation was important throughout the study, and may have significantly altered the molecular composition of the aerosol during transport.     

The impact of wood smoke on ambient PM2.5 in northern Rocky Mountain valley communities

During the winters of 2006/2007 and 2007/2008, PM_2.5 source apportionment programs were carried out within five western Montana valley communities. Filter samples were analyzed for mass and chemical composition. Information was utilized in a Chemical Mass Balance (CMB) computer model to apportion the sources of PM_2.5. Results showed that wood smoke (likely residential woodstoves) was the major source of PM_2.5 in each of the communities, contributing from 56% to 77% of the measured wintertime PM_2.5. Results of ¹⁴C analyses showed that between 44% and 76% of the measured PM_2.5 came from a new carbon (wood smoke) source, confirming the results of the CMB modeling. In summary, the CMB model results, coupled with the ¹⁴C results, support that wood smoke is the major contributor to the overall PM_2.5 mass in these rural, northern Rocky Mountain airsheds throughout the winter months.     

The solvent-extractable organic compounds in the Indonesia biomass burning aerosols – characterization studies

The large-scale air pollution episode due to the out-of-control biomass burning for agricultural purposes in Indonesia started in June 1997, has become a severe environmental problem for itself and the neighboring countries. The fire lasted for almost five months. Its impact on the health and ecology in the affected areas is expected to be substantial, costly and possibly long lasting. Air pollution Index as high as 839 has been reported in Malaysia. API is calculated based on the five pollutants: NO₂, SO₂, O₃, CO, and respirable suspended particulates (PM10). It ranges in value from 0 to 500. An index above 101 is considered to be unhealthy and a value over 201 is very unhealthy (Abidin and Shin, 1996).The solvent-extractable organic compounds from four total suspended particulate (TSP) high-volume samples collected in Kuala Lumpur, Malaysia (Stations Pudu and SIRIM) were subjected to characterization – the abundance was determined and biomarkers were identified. Two of the samples were from early September when the fire was less intense, while the other two were from late September when Kuala Lumpur experienced very heavy smoke coverage which could be easily observed from NOAA/AVHRR satellite images. The samples contained mainly aliphatic hydrocarbons such as n-alkanes and triterpanes, alkanoic acids, alkanols, and polycyclic aromatic hydrocarbons. The difference between the early and late September samples was very significant. The total yield increased from 0.6 to 24.3 μg m^-3 at Pudu and 1.9 to 20.1 μg m^-3 at SIRIM, with increases in concentration in every class. The higher input of vascular plant wax components in the late September samples, when the fire was more intense, was characterized by the distribution patterns of the homologous series n-alkanes, n-alkanoic acids, and n-alkanols, e.g., lower U : R, higher >C₂₂/<C₂₀ for n-alkanoic acids, higher >C₂₀/<C₂₀ for n-alkanols, a shift in C_max from C₁₆ to C₂₆ for n-alkanoic acids and C₁₈ to C₂₈ for n-alkanols, and the presence of abundant moretane (17β(H), 21α(H)-hopanes). The biomarkers dehydroabietic acid and retene were not found in the samples suggesting there is a difference in the long-distance transport samples of an Asian forest fire and the controlled experiments reported in the literature. Similar to the biomass burning in Amazonia (Abas et al., 1995), the present study also showed an absence of conifer tracers in the smoke aerosols indicating tropical wood sources. Abundant friedelin, a specific biomarker for smoke from oak wood fires (Standley and Simoneit, 1990), was present in the late September samples when the fire was more intense. The results were compared to literature values from an earlier study of the haze episode on 29 September 1991 in Kuala Lumpur, Malaysia (Abas and Simoneit, 1996).     

Size Distribution and Sources of Aerosol in Launceston,Australia, during Winter 1997

ABSTRACT

As part of a pilot study into the chemical and physical properties of Australian fine particles, a suite of aerosol samples was collected at Ti Tree Bend in Launceston, Tasmania, during June and July 1997. This period represents midwinter in the Southern Hemisphere, a period when aerosol sources in Launceston are dominated by smoke from domestic wood burning. This paper describes the results from this measurement campaign, with the aim of assessing the effect of wood smoke on the chemical and physical characteristics of ambient aerosol. A micro orifice uniform deposit impactor (MOUDI) was used to measure the size distributions of the aerosol from 0.05 to 20 n m aerodynamic diameter. Continuous measurements of fine particle mass were made using a PM_2.5 tapered element oscillating microbalance (TEOM) and light scattering coefficients at 530 nm were measured with nephelometers.

Mass size distributions tended to be bimodal, with the diameter of the dominant mode tending to smaller sizes with increases in total mass. Non-sea salt potassium and polycyclic aromatic hydrocarbons (PAHs) were used as chemical tracers for wood smoke. Wood smoke was found to increase absolute particle mass (enough to regularly exceed air quality standards), and to concentrate mass in a single mode below 1 μm aerodynamic diameter. The acid-base equilibrium of the aerosol was altered by the wood smoke source, with free acidity hydrogen ion, non-sea salt sulfate, and ammonium concentrations being higher and the concentration of all species, including nitrate (to differing extents), focused in the fine particle size ranges. The wood smoke source also heavily influenced the aerosol scattering efficiency, adding to a strong diurnal cycle in both mass concentration and light scattering.     

Source apportionment of fine particles at urban background and rural sites in the UK atmosphere

Airborne fine particulate matter (PM_2.5) has been collected at two sites in the West Midlands conurbation, UK, representing urban background and rural locations. Chemical analyses have been carried out for major anions, trace metals, total OC and EC, and for individual organic marker species including n-alkanes, hopanes, PAHs, organic acids and sterols. Source apportionment has been conducted using both a pragmatic mass closure model and the US EPA chemical mass balance (CMB) model. The pragmatic mass closure model is well able to account for the measured PM_2.5 mass in terms of chemical/source components, and the chemical mass balance model has been used to apportion the carbonaceous component of the aerosol. The dominant components of PM_2.5 at both sites are secondary inorganic (sulphate and nitrate) and carbonaceous particles. The CMB model shows the latter to arise mainly from road traffic sources, with smaller contributions from vegetative detritus, wood smoke, natural gas, coal, and dust/soil. The CMB model also identifies an important component of the organic aerosol not associated with these primary sources, which correlates very strongly with secondary organic aerosol estimated from the OC/EC ratio. The split between different automotive source types does not relate well to UK emission inventories, and may indicate that CMB source profiles from North American studies and different carbon analysis protocols may lead to erroneous conclusions.     

Temporal variation and impact of wood smoke pollution on a residential area in southern Germany

This paper is a continuation of our previous publication (Bari, M.A., Baumbach, G., Kuch, B., Scheffknecht, G., 2009. Wood smoke as a source of particle-phase organic compounds in residential areas. Atmospheric Environment 43, 4722–4732) and describes a detailed characterisation of different particle-phase wood smoke tracer compounds in order to find out the impact of wood-fired heating on ambient PM₁₀ pollution in a residential area near Stuttgart in southern Germany. The results from previous flue gas measurements help distinguishing different tracer compounds in ambient PM₁₀ samples. In the residential area, significant amounts of hardwood markers (syringaldehyde, acetosyringone, propionylsyringol, sinapylaldehyde) and low concentrations of softwood markers (vanillin, acetovanillone, coniferyldehyde, dehydroabietic acid, retene) were found in the ambient air. The general wood combustion markers Levoglucosan, mannosan and galactosan were detected in high concentrations in all particle-phase PM₁₀ samples. To find out the size distribution of ambient particles, cascade impactor measurements were carried out. It was found that more than 70% of particulate matter was in the particle diameter of less than 1 μm. Using emission ratio of levoglucosan to PM₁₀, it can be demonstrated that during winter months 59% of ambient PM₁₀ pollution could be attributed to residential wood-fired heating.     

Is remaining indoors an effective way of reducing exposure to fine particulate matter during biomass burning events?

Bushfires, prescribed burns, and residential wood burning are significant sources of fine particles (aerodynamic diameter <2.5 μm; PM_2.5) affecting the health and well-being of many communities. Despite the lack of evidence, a common public health recommendation is to remain indoors, assuming that the home provides a protective barrier against ambient PM_2.5. The study aimed to assess to what extent houses provide protection against peak concentrations of outdoor PM_2.5 and whether remaining indoors is an effective way of reducing exposure to PM_2.5. The effectiveness of this strategy was evaluated by conducting simultaneous week-long indoor and outdoor measurements of PM_2.5 at 21 residences in regional areas of Victoria, Australia. During smoke plume events, remaining indoors protected residents from peak outdoor PM_2.5 concentrations, but the level of protection was highly variable, ranging from 12% to 76%. Housing stock (e.g., age of the house) and ventilation (e.g., having windows/doors open or closed) played a significant role in the infiltration of outdoor PM_2.5 indoors. The results also showed that leaving windows and doors closed once the smoke plume abates trapped PM_2.5 indoors and increased indoor exposure to PM_2.5. Furthermore, for approximately 50% of households, indoor sources such as cooking activities, smoking, and burning candles or incense contributed significantly to indoor PM_2.5.

Implications: Smoke from biomass burning sources can significantly impact on communities. Remaining indoors with windows and doors closed is a common recommendation by health authorities to minimize exposures to peak concentrations of fine particles during smoke plume events. Findings from this study have shown that the protection from fine particles in biomass burning smoke is highly variable among houses, with information on housing age and ventilation status providing an approximate assessment on the protection of a house. Leaving windows closed once a smoke plume abates traps particles indoors and increases exposures.     

Analysis of particle-associated semi-volatile aromatic and aliphatic hydrocarbons in urban particulate matter on a daily basis

PM_2.5 Particle-associated semi-volatile organic compounds (SVOC) were determined in the city of Augsburg, Germany. Daily samples were collected at a central monitoring station from late summer to late autumn 2002. The concentrations of polycyclic aromatic hydrocarbons (PAH), oxidized PAH (O-PAH), n-alkanes, hopanes and long chain linear alkylbenzenes were determined by direct thermal desorption-gas chromatography-time of flight mass spectrometry (DTD-GC-TOFMS). Additionally, PM_2.5 particle mass and number concentrations were measured. The sampling campaign can be divided into two parts, distinguished by a lower temperature level in the second part of the campaign. The particulate mass concentration showed no significant changes, whereas most of the SVOC had significant higher mean and peak concentrations in the colder period. The analysis of the data showed an increased influence of non-traffic sources in the colder period, reflected by a weak shift in the PAH profile and a significant shift in the hopane pattern. Statistical analysis of the inter-group correlations was carried out. Eight clusters partly representing different sources of the aerosol have been identified.     

Composition of extractable organic matter of air particles from rural and urban Portuguese areas

Atmospheric particulate matter (PM₁₀) was collected simultaneously at three sites in the West Coast of Portugal, during an intensive campaign in August 1996. The sites were located in line with the breezes blowing from the sea. The collected aerosol was analysed in relation to black and organic carbon content. The particulate organic matter was extracted with solvents and characterised by gas chromatography and mass spectrometry (GC–MS). Most of the organic mass identified consists of alkanes, polycyclic aromatic hydrocarbons (PAH), ketones, aldehydes, alcohols and fatty acids with both biogenic and anthropogenic origin. Many photochemical products from volatile organic compounds emitted by vegetation were also detected. Biomarkers such as 6,10,14-trimethylpentadecanone, abieta-8,11,13-trien-7-one and Patchouli alcohol were observed at higher concentrations in the rural sites. Samples from the urban site present lower values of “carbon preference index” and higher concentrations of petrogenic/pyrogenic species, such as PAH. The PM₁₀ concentrations and the total organic extract measured for the more interior site were generally lower, indicating that dispersion and dry deposition into the forest canopy were more important during the transport of the air masses than aerosol production by condensation and photochemical reactions. On the contrary, the ratio between organic and black carbon was, in general, lower at sites near the coast, especially for compounds that evaporate at lower temperatures. The organic aerosol composition also seems to be strongly dependent on the meteorology.