Fine Particle Mass Concentrations Research Articles

Risk in Perspective: Insight and Humor in the Age of Risk Management

A method for estimating long-term exposures from short-term measurements is validated using data from a recent EPA study of exposure to fine particles. The method was developed a decade ago but long-term exposure data to validate it did not exist until recently. In this article, exposure data from repeated visits to 37 persons over 1 year (up to 28 measurements per person) are used to test the model. Both fine particle mass and elemental concentrations measured indoors, outdoors, and on the person are examined. To provide the most stringent test of the method, only two single-day distributions are randomly selected for each element to predict the long-term distributions. The precision of the method in estimating the long-term geometric mean and geometric standard deviation appears to be of the order of 10%, with no apparent bias. The precision in estimating the 99 th percentile ranges from 19% to 48%, again without obvious bias. The precision can be improved by selecting a number of pairs of single-day distributions instead of just one pair. Occasionally, the method fails to provide an estimate for the long-term distribution. In that case, a repeat of the random selection procedure can provide an estimate. Although the method assumes a log-normal distribution, most of the distributions tested failed the chi-square test for log-normality. Therefore, the method appears suitable for application to distributions that depart from log-normality.

Measurements of Fine Particle Mass Concentrations Using Continuous and Integrated Monitors in Eastern US Cities

PM2.5 mass concentrations were measured using multiple continuous samplers (a continuous ambient mass monitor (CAMM), a real–time ambient mass sampler (RAMS), and a drier–equipped tapered element oscillating microbalance (TEOM)) as well as a federal reference method (FRM) filter sampler in three eastern US cities. The effects of measurement systems, ambient conditions, and composition on the measured PM2.5 mass concentrations were examined at each site. Different responses to PM2.5 mass were observed by the continuous samplers with a variation of 10–30% in the average PM mass concentrations. The impacts of semivolatile particulate ammonium nitrate on PM2.5 mass concentration was apparent for those time periods when high nitrate concentration >1.62 g m−3 was measured in Atlanta. Contribution of semivolatile particulate ammonium nitrate to the ambient PM2.5 mass appeared more significant than semivolatile organic material in Atlanta. The effects of the ambient water were not negligible and were significant ...

Fine particle number and mass concentration measurements in urban Indian households

Fine particle number concentration ( D p>10 nm, cm −3), mass concentrations (approximation of PM 2.5, μg m −3) and indoor/outdoor number concentration ratio (I/O) measurements have been conducted for the first time in 11 urban households in India, 2002. The results indicate remarkable high indoor number and mass concentrations and I/O number concentration ratios caused by cooking. Besides cooking stoves that used liquefied petroleum gas (LPG) or kerosene as the main fuel, high indoor concentrations can be explained by poor ventilation systems. Particle number concentrations of more than 300,000 cm −3 and mass concentrations of more than 1000 μg m −3 were detected in some cases. When the number and mass concentrations during cooking times were statistically compared, a correlation coefficient r>0.50 was observed in 63% of the households. Some households used other fuels like wood and dung cakes along with the main fuel, but also other living activities influenced the concentrations. In some areas, outdoor combustion processes had a negative impact on indoor air quality. The maximum concentrations observed in most cases were due to indoor combustion sources. Reduction of exposure risk and health effects caused by poor indoor air in urban Indian households is possible by improving indoor ventilation and reducing penetration of outdoor particles.

Manual synoptic climate classification for the east coast of New England (USA) with an application to PM2.5 concentration

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 28:143-153 (2005) - doi:10.3354/cr028143 Manual synoptic climate classification for the east coast of New England (USA) with an application to PM2.5 concentration Barry D. Keim1,*, Loren David Meeker2, John F. Slater3 1Department of Geography and Anthropology, Louisiana State University, 327E Howe-Russell Science Complex, Baton Rouge, Louisiana 70803, USA2Climate Change Research Center, University of New Hampshire, 56 College Road, Durham, New Hampshire 03824, USA3Division of Engineering, Math, and Science, Daniel Webster College, 20 University Drive, Nashua, New Hampshire 03063, USA *Email: keim@lsu.edu ABSTRACT: This study presents a manual synoptic climate classification for the East Coast of New England with an application to regional pollution. New England weather was classified into 9 all-inclusive weather types: Canadian High, Modified High, Gulf of Maine Return, New England High, Atlantic Return, Frontal Atlantic Return, Frontal Overrunning–Continental, Frontal Overrunning–Marine, and Tropical Disturbance. Canadian High and Modified High weather are the dominant weather patterns at Boston, Massachusetts, while Tropical Disturbance, Gulf of Maine Return, and New England High weather types are the least frequent. Properties of the weather types were determined at 07:00 h Local Standard Time (LST) each day in Boston. The coldest and driest weather type is the Canadian High, while the hottest, most humid weather is generated by Frontal Atlantic Return. The synoptic weather classification system, applied to airborne fine particle mass concentrations with an aerodynamic diameter ≤2.5 µm (PM2.5), showed significant differences in concentrations between weather types: transport from the north and northwest had low PM2.5, while transport from the south and southwest had high PM2.5 concentrations. This climate classification system also has potential applications ranging from studies of insect migration to analyses of climate change. KEY WORDS: synoptic climatology · New England · USA · Boston · weather types · applied climatology · PM2.5 Full article in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 28, No. 2. Online publication date: March 16, 2005 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2005 Inter-Research.

A case study of the single and size-resolved particles in roadway tunnel in Seoul, Korea

Abstract Particle sampling was conducted at the center of Buk-Ak tunnel, which is one of heavily polluted tunnels in Seoul, in October 2000. The sampling equipments consist of a 2-stage filter pack sampler and an Andersen impactor sampler. Micro-particle induced X-ray emission (PIXE) was applied to determine the elemental composition of individual particles (>1.2 μm). The thermal/optical reflectance (TOR ® ) method was also employed in analyzing of EC and OC. Mass concentrations of fine and coarse particles are 177 and 40 μg m −3 , respectively. The most important contributor to particle mass concentration in the present study is carbonaceous components. Most of the individual particles are found to be internally mixed with soil-derived and trace elemental components.

Regional haze in Wisconsin: sources and the spatial distribution

The atmospheric fine particulate matter (PM2.5) chemical composition and the light scattering coefficient were measured at a rural air monitoring site in Wisconsin between September 2001 and August 2002 to understand the source of regional haze in the area. The average fine particle mass concentration, was 10.8 µg/m3 over this time period and was 27.2% organic material, 2.4% elemental carbon, 34.2% ammonium sulfate, 31.6% ammonium nitrate, 3.7% soil, and 1.8% non-soil trace elements. Ammonium sulfate, organic matter, and soil were highest during the summer period while ammonium nitrate was highest during the winter. Elemental carbon peaked in the fall while the trace elements did not vary significantly. These trends were also observed at an urban Milwaukee site. A comparison of spring 2002 data between sites distributed across Wisconsin revealed a similar relative chemical composition, though absolute concentrations varied significantly. The average measured light scattering coefficient (bsp) at the rural sampling site was 53 ± 1 Mm–1. The PM2.5 mass and the measured bsp showed good correlation with an R2 of 0.84. The average chemical composition of the particulate matter was used to calculate bsp and the resulting values agree well with the measured bsp, though not as well as the PM2.5 mass, giving a regression slope of 1.06 and an R2 of 0.72. Key words: PM2.5 chemical speciation, light scattering coefficient, visibility.

Indoor Fine Particles: The Role of Terpene Emissions from Consumer Products

Consumer products can emit significant quantities of terpenes, which can react with ozone (O3). Resulting byproducts include compounds with low vapor pressures that contribute to the growth of secondary organic aerosols (SOAs). The focus of this study was to evaluate the potential for SOA growth, in the presence of O3, following the use of a lime-scented liquid air freshener, a pine-scented solid air freshener, a lemon-scented general-purpose cleaner, a wood floor cleaner, and a perfume. Two chamber experiments were performed for each of these five terpene-containing agents, one at an elevated O3 concentration and the other at a lower O3 concentration. Particle number and mass concentrations increased and O3 concentrations decreased during each experiment. Experiments with terpene-based air fresheners produced the highest increases in particle number and mass concentrations. The results of this study clearly demonstrate that homogeneous reactions between O3 and terpenes from various consumer products can lead to increases in fine particle mass concentrations when these products are used indoors. Particle increases can occur during periods of elevated outdoor O3 concentrations or indoor O3 generation, coupled with elevated terpene releases. Human exposure to fine particles can be reduced by minimizing indoor terpene concentrations or O3 concentrations.

Variability of apparent particle density of an urban aerosol.

The day to day and diurnal variation of apparent particle density was studied using highly time-resolved measurements of particle number distribution and fine-particle mass concentration. The study was conducted in Erfurt, Germany, from January 1, 1999, to November 22, 2000. A setup consisting of a differential mobility particle spectrometer and a laser aerosol spectrometer was used for particle number distribution measurements. PM2.5 particle mass was measured in parallel on an hourly basis using a tapered element oscillating microbalance (TEOM) and on daily base by using a Harvard marple impactor (HI). For the estimation of the mean apparent density of particles, number size distributions were converted into volume size distributions, assuming that the particles were spherically shaped. The volume size distributions were integrated over the range of 10 nm to 2.03 microm Stokes equivalent diameter to obtain volume concentrations. Mean apparent particle density was calculated as ratio of mass concentration and volume concentration. The mean apparent particle density, determined from HI and number size distribution on a daily basis was 1.6 +/- 0.5 g cm(-3). We found a strong day-to-day variation of apparent density ranging from 1.0 to 2.5 g cm(-3) (5th and 95th percentile). Furthermore, the apparent density showed pronounced diurnal pattern both in summer and in winter and also on weekdays and weekends. The apparent density was lowest in the morning and highest in the afternoon. The mean apparent density on an hourly basis was 1.4 +/- 0.5 and 1.5 +/- 0.5 g cm(-3) for PM2.5TEOM and corrected PM2.5TEOM using regression equation between daily mass concentration of HI and TEOM, respectively. The strong diurnal variation of apparent particle density was associated predominantly with the vertical temperature inversion and with traffic intensity. Thus, the apparent particle density depends on the physical particle properties and might be related to chemical composition of the sampled particle.

EFFECTS OF PARTICULATE AIR POLLUTION ON ELECTROCARDIOGRAM (ECG) PARAMETER IN CORONARY ARTERY DISEASE PATIENTS

Air pollution episodes have been associated with increased risk of cardiac death. Cardiac death is an outgrowth of a defective interplay between the autonomic cardiac function, the myocardial substrate and the myocardial vulnerability. A prospective panel study with up to 12 repeated clinical visits was conducted in 58 males with coronary artery disease in Erfurt, East Germany in order to assess short term effects of ambient air pollution on cardiovascular health. As part of the study protocol a 12-lead ECG was recorded. The aim of this analysis was to evaluate the effect of particulates air pollution on ECG measures of autonomic function (SDNN and RMSSD), myocardial substrate (QTc, T complexity and T amplitude) and myocardial vulnerability (variability of QT peak and of T complexity) during a 6-minute period of resting supine with spontaneous breathing. Fine particle mass (PM2.5) and ultrafine particle number concentrations (UFP) were measured at a central measuring site. Fixed effect linear regression analysis was used to model the association between 24-hour mean concentrations of air pollutants and repolarization parameters adjusting for subject, trend, weekday, air temperature, barometric air pressure and relative humidity. No association was found between particles and SDNN. Only a weak association was observed for RMSSD. T wave complexity increased with same day PM2.5 (3.6% per 13 μg/m3 (95% confidence interval (CI): 0.6% to 6.6%)) and with same day UFP (1.9% per 9830 cm-3 (95% CI: −2.06% to 5.8%)). Consistently, T wave amplitude decreased with same day PM2.5 (−1.6% per 13 μg/m3 (95% CI: −3.4% to 0.1%)) and with same day UFP (−2.6% per 9830 cm-3 (95% CI: −5.3% to −0.1%)). The results suggest that these changes in myocardial function associated with PM2.5 and UFP could precipitate arrhythmic events especially in susceptible individuals. Funded by: US EPA STRA centre grant R-827354 (2003; 14: 000–000)

Analytical Solutions to Compartmental Indoor Air Quality Models with Application to Environmental Tobacco Smoke Concentrations Measured in a House

This paper derives the analytical solutions to multi-compartment indoor air quality models for predicting indoor air pollutant concentrations in the home and evaluates the solutions using experimental measurements in the rooms of a single-story residence. The model uses Laplace transform methods to solve the mass balance equations for two interconnected compartments, obtaining analytical solutions that can be applied without a computer. Environmental tobacco smoke (ETS) sources such as the cigarette typically emit pollutants for relatively short times (7-11 min) and are represented mathematically by a “rectangular” source emission time function, or approximated by a short-duration source called an “impulse” time function. Other time-varying indoor sources also can be represented by Laplace transforms. The two-compartment model is more complicated than the single-compartment model and has more parameters, including the cigarette or combustion source emission rate as a function of time, room volumes, compartmental air change rates, and interzonal air flow factors expressed as dimensionless ratios. This paper provides analytical solutions for the impulse, step (Heaviside), and rectangular source emission time functions. It evaluates the indoor model in an unoccupied two-bedroom home using cigars and cigarettes as sources with continuous measurements of carbon monoxide (CO), respirable suspended particles (RSP), and particulate polycyclic aromatic hydrocarbons (PPAH). Fine particle mass concentrations (RSP or PM3.5) are measured using real-time monitors.In our experiments, simultaneous measurements of concentrations at three heights in a bedroom confirm an important assumption of the model-spatial uniformity of mixing. The parameter values of the two-compartment model were obtained using a “grid search” optimization method, and the predicted solutions agreed well with the measured concentration time series in the rooms of the home. The door and window positions in each room had considerable effect on the pollutant concentrations observed in the home. Because of the small volumes and low air change rates of most homes, indoor pollutant concentrations from smoking activity in a home can be very high and can persist at measurable levels indoors for many hours.

Diverging long-term trends in ambient urban particle mass and number concentrations associated with emission changes caused by the German unification

Air quality in urban areas has considerably changed over time. Recent changes of particle emissions in Eastern Germany during the last 10 years provide a quick motion picture of a development which lasted several decades in Western countries. Size distributions of fine particles (<2.5 μm aerodynamic diameter) were measured during winters 1991/1992 through 2000/2001. Within these 10 years particle size distributions shifted strongly towards smaller sizes. This was mainly due to a twofold increase of the number concentration of 0.01–0.03 μm sized particles. In parallel, fine particle mass concentration decreased by 75%. Since the mass concentration of fine particles is considered most relevant for human health today, the observed substantially decreasing trend in Eastern Germany is a desirable development. It is, however, accompanied by an increase of the number concentration of ultrafine particles in the 0.01–0.03 μm size range for which most recently associations with health effects have been found. This development associated with rapid emission changes caused by the German unification may be considered as a time-lapsed development representing partially unrecorded temporal alterations of emissions in a large entity of Western industrialized urban environments over the last five decades. Thus, the worldwide policy to reduce only the mass concentration of ambient aerosols without controlling for the number concentration may not be sufficient to assess health effects associated with urban particles.

Trimethylsilyl derivatives of organic compounds in source samples and in atmospheric fine particulate matter.

Source sample extracts of vegetative detritus, motor vehicle exhaust, tire dust paved road dust, and cigarette smoke have been silylated and analyzed by GC-MS to identify polar organic compounds that may serve as tracers for those specific emission sources of atmospheric fine particulate matter. Candidate molecular tracers were also identified in atmospheric fine particle samples collected in the San Joaquin Valley of California. A series of normal primary alkanols, dominated by even carbon-numbered homologues from C26 to C32, the secondary alcohol 10-nonacosanol, and some phytosterols are prominent polar compounds in the vegetative detritus source sample. No new polar organic compounds are found in the motor vehicle exhaust samples. Several hydrogenated resin acids are present in the tire dust sample, which might serve as useful tracers for those sources in areas that are heavily impacted by motor vehicle traffic. Finally, the alcohol and sterol emission profiles developed for all the source samples examined in this project are scaled according to the ambient fine particle mass concentrations attributed to those sources by a chemical mass balance receptor model that was previously applied to the San Joaquin Valley to compute the predicted atmospheric concentrations of individual alcohols and sterols. The resulting underprediction of alkanol concentrations at the urban sites suggests that alkanols may be more sensitive tracers for natural background from vegetative emissions (i.e., waxes) than the high molecular weight alkanes, which have been the best previously available tracers for that source.

Increased asthma medication use in association with ambient fine and ultrafine particles

The association between particulate air pollution and asthma medication use and symptoms was assessed in a panel study of 53 adult asthmatics in Erfurt, Germany in winter 1996/1997. Number concentrations of ultrafine particles, 0.01-0.1 microm in diameter (NC(0.01-0.1), mean 17,300 x cm(-3), and mass concentrations of fine particles 0.01-2.5 microm in diameter (MC(0.01-2.5)), mean 30.3 microg x m(-3), were measured concurrently. They were not highly correlated (r=0.45). The associations between ambient particle concentrations and the prevalence of inhaled beta2-agonist, corticosteroid use and asthma symptoms, were analysed separately with logistic regression models, adjusting for trend, temperature, weekend, holidays, and first order autocorrelation of the error. Cumulative exposures over 14 days of ultrafine and fine particles were associated with corticosteroid use. Beta2-agonist use was associated with 5-day mean NC(0.01-0.1) and MC(0.01-2.5). The prevalence of asthma symptoms was associated with ambient particle concentrations. The results suggest that reported asthma medication use and symptoms increase in association with particulate air pollution and gaseous pollutants such as nitrogen dioxide.

Evolution of nitrogen species air pollutants along trajectories crossing the Los Angeles area.

Ambient aerosol sampling was conducted in Diamond Bar, Mira Loma, and Riverside, CA, to observe at close range the effects of ammonia emissions on air quality. These sites are located upwind,within, and downwind, respectively, of the Chino dairy area, the largest single source of ammonia emissions in the Los Angeles area. Inertial impactors and bulk filter samplers provided 4-7-h measurements of aerosol chemical composition and size distribution. Daily average fine particle mass concentrations were in the range 22.4-143.0 microg m(-3). On some days the fine particulate matter concentrations were more than two times greater than the proposed 24-h Federal standard of 65 microg m(-3). Ammonium nitrate was the largest component of fine particle mass at all three sites; 24-h average fine particulate ammonium plus nitrate concentrations ranged from 11.7 to 75.4 microg m(-3). A single air mass was studied as it passed the Diamond Bar air monitoring site in the morning and stagnated near Mira Loma in the evening of the same day. Between these two sites NO was oxidized to NO2, and the ammonia concentration increased by a factor of 5. A second air parcel trajectory, which stagnated near Mira Loma during the early morning and passed near the Riverside site approximately 24 h later, showed a decrease in ammonia concentration over time that is consistent with dilution as the air mass moved downwind from the source of ammonia in the dairy area. Particulate NH4NO3 concentration in that air parcel remained approximately constant over time, consistent with a continued excess of NH3 relative to HNO3 downwind of the dairy area.

Measurements and modelling of PM 2.5 concentrations near a major road in Kuopio, Finland

A particle measurement campaign was conducted in a suburban environment near a major road in Kuopio, Central Finland from 3 August to 9 September 1999. The mass concentrations of fine particles (PM 2.5) were measured simultaneously at distances of 12, 25, 52 and 87 m from the centre of a major road at a height of 1.8 m, using identical samplers. The concentration measurements were conducted during 16 daytime hours (from 6.00 a.m. to 10.00 p.m.) for 27 days. Traffic flows and relevant meteorological parameters were measured on-site; meteorological measurements from a nearby synoptic weather station were also utilised. We also suggest a preliminary model for predicting the concentrations of PM 2.5 and apply this model in order to analyse the measured data. The regionally and long-range transported contribution was evaluated on the basis of a semi-empirical mathematical model utilising as input values the daily sulphate, nitrate and ammonium measurements at the EMEP stations (Co-operative programme for monitoring and evaluation of the long-range transmission of air pollutants in Europe). The influence of primary vehicular emissions from the nearest roads was evaluated using a roadside emission and dispersion model, CAR-FMI, in combination with a meteorological pre-processing model, MPP-FMI. The contribution of non-exhaust particulate matter emissions (including resuspension of particulate matter from road surfaces) was estimated simply to be directly proportional to the concentrations originating from primary vehicular emissions. Comparison of the predicted results and measurements yields information on the relative importance of various source categories of the measured concentrations of PM 2.5. The regionally and long-range transported contribution, the primary and non-exhaust vehicular emissions, and other sources were estimated to contribute on average 41±6%, 33±6% and 26±7% of the observed PM 2.5 concentrations, respectively. The model presented could also be applied in other European cities for analysing the source contributions to measured fine particulate matter concentrations.

Atmospheric particle size and composition measurements to support light extinction calculations over the Indian Ocean

The size distribution and chemical composition of the atmospheric aerosol at the Kaashidhoo Climate Observatory (KCO) in the Republic of Maldives was determined during the winter northeast monsoon season to aid in determining the light scattering and light absorption properties of the aerosol particles in that region. These experiments were conducted over 8 two‐day periods during February 11–26, 1999, using filter‐based samplers and cascade impactors operated at ambient relative humidity which was in the range of 80–89% relative humidity over 83% of the period sampled. Fine particle concentrations (Da&lt;1.8 μm) averaged 17.7(±0.22) μg m−3 and varied between 8.4(±0.33)–24.7(±0.21) μg m−3 over the period studied. Sulfate ion and carbonaceous aerosols are the largest contributors to the fine particle mass concentration, accounting for 33–37% and 26–27% of the fine mass, respectively. Calcium carbonate contributes 3% of the mass measured on the impactor stages. Ammonium, nitrate, and chloride ion account for 7–9, 1, and 0–1% of the fine particle mass, respectively. The residual mass of as yet undetermined fine particle material stands at 28–30%. Black elemental carbon particles contribute 6–11% of the fine particle mass concentration and dominate light absorption in the atmosphere at KCO (A. Eldering et al., unpublished manuscript, 2001). These fine particle concentrations are comparable to those found in major cities in the United States and are surprisingly high for a remote location such as the Maldive Islands, which is located downwind of the Indian subcontinent.

Sources and chemical composition of atmospheric fine and coarse particles in the Helsinki area

During April 1996–June 1997 size-segregated atmospheric aerosol particles were collected at an urban and a rural site in the Helsinki area by utilising virtual impactors (VI) and Berner low-pressure impactors (BLPI). In addition, VI samples were collected at a semi-urban site during October 1996–May 1997. The average PM 2.3 (fine particle) concentrations at the urban and rural sites were 11.8 and 8.4 μg/m 3, and the PM 2.3−15 (coarse particle) concentrations were 12.8 and about 5 μg/m 3, respectively. The difference in fine particle mass concentrations suggests that on average, more than one third of the fine mass at the urban site is of local origin. Evaporation of fine particle nitrate from the VI Teflon filters during sampling varied similarly at the three sites, the average evaporation being about 50–60%. The average fine particle concentrations of the chemical components (25 elements and 13 ions) appeared to be fairly similar at the three sites for most components, which suggests that despite the long-range transport, the local emissions of these components were relatively evenly distributed in the Helsinki area. Exceptions were the average fine particles Ba, Fe, Sb and V concentrations that were clearly highest at the urban site pointing to traffic (Ba, Fe, Sb) and to combustion of heavy fuel oil (V) as the likely local sources. The average coarse particle concentrations for most components were highest at the urban site and lowest at the rural site. Average chemical composition of fine particles was fairly similar at the urban and rural sites: non-analysed fraction (mainly carbonaceous material and water) 43% and 37%, sulphate 21% and 25%, crustal matter 12% and 13%, nitrate 12% and 11%, ammonium 9% and 10% and sea-salt 2.5% and 3.2%, respectively. At the semi-urban site also, the average fine particle composition was similar. At the urban site, the year round average composition of coarse particles was dominated by crustal matter (59%) and the non-analysed components (28%, mainly carbonaceous material and water), while the other contributions were much lower: sea-salt 7%, nitrate 4% and sulphate 2%. At the rural site, the coarse samples were collected in spring and summer and the percentage was clearly lower for crustal matter (37%) and sea-salt (3%) but higher for the not-analysed fraction (51%). At the semi-urban site, the average composition of coarse particles was nearly identical to that at the urban site. Correlations between the chemical components were calculated separately for fine and coarse particles. In urban fine particles sulphate, ammonium, Tl, oxalate and PM 2.3 mass correlated with each other and originated mainly from long-range transport. The sea-salt ions Na +, Cl − and Mg 2+ formed another group and still another group was formed by the organic anions oxalate, malonate, succinate, glutarate and methane sulphonate. Ni and V correlated strongly pointing to combustion of heavy fuel oil as the likely source. In addition, some groups with lower correlations were detected. At the rural and semi-urban sites, the correlating components were rather similar to those at the urban site, although differences were also observed.

Change of the ambient particle size distribution in East Germany between 1993 and 1999

Size distribution of particle number concentrations in the geometric equivalent diameter range 0.01–2.5 μm were determined in three communities, Zerbst, Bitterfeld and Hettstedt of the state of Sachsen-Anhalt in Eastern Germany, in the first half of 1993 and 1999. A Mobile Aerosol Spectrometer (MAS) consisting of a differential mobility particle spectrometer (DMPS) and a laser aerosol spectrometer (LAS-X) were used for size-selective particle number concentration measurements from which mass concentrations were derived based on an apparent mean density of the ambient aerosol of the closely situated city of Erfurt. The total number concentration was governed by ultra-fine particles (<0.1 μm) (81% in 1993 and 90% in 1999) and 0.1–0.5 μm size fraction dominates total mass concentration (approximately 80%). While the mass concentration of fine particles (PM2.5) decreased from 39 to 19 μg m −3, the geometric means of total number concentration showed constant concentration (13.3×10 3 cm −3 in 1993 and 13.3×10 3 cm −3 in 1999, p=0.975) and the geometric means of number concentration of ultra-fine particles (UP) between 10 and 30 nm increased from 5.9×10 3 to 8.2×10 3 cm −3 from 1993 to 1999 ( p=0.016). The temporal changes of number and mass concentrations in the three communities are similar. The clear shift to smaller particle sizes within this six years period was caused by changes of the most prominent sources, traffic and domestic heating, since formerly dominating industries in Bitterfeld and Hettstedt had vanished grossly.

Source Apportionment of Wintertime Gas-Phase and Particle-Phase Air Pollutants Using Organic Compounds as Tracers

Two chemical mass balance receptor models are developed which can determine the source contributions to atmospheric pollutant concentrations using organic compounds as tracers. The first model uses particle-phase organic compounds to apportion the primary source contributions to atmospheric fine particulate organic carbon concentrations and fine particle mass concentrations. The second receptor model simultaneously uses both volatile gas-phase hydrocarbons and particle-phase organic compounds as tracers to determine source contributions to non-methane organic gases in the atmosphere. Both models are applied to data collected in California's San Joaquin Valley during two severe wintertime air pollution episodes. Source contributions to fine particle air quality are calculated for two urban sites, Fresno and Bakersfield, and one background site, Kern Wildlife Refuge. Primary particle emissions from hardwood combustion, softwood combustion, diesel engines, meat cooking, and gasoline-powered motor vehicles contribute on average 79% of the airborne fine particle organic compound mass at the urban sites during both episodes with smaller but still measurable contributions from fine particle road dust and natural gas combustion aerosol. Anthropogenic primary particle sources contribute less than 10% of the fine particle mass concentration at the background site. The combined gas-phase and particle-phase organic compound receptor model shows that gasoline-powered motor vehicle exhaust and gasoline vapors are the largest contributors to non-methane organic gases concentrations followed by natural gas leakage. Smaller but statistically significant contributions to organic vapors from wood combustion, meat cooking, and diesel exhaust also are quantified.

A case study of gas‐to‐particle conversion in an eastern Canadian forest

Aerosol and trace gas measurements were made at Kejimkujik National Park, Nova Scotia, Canada, during the summer of 1996. A case study from July 7–8 provides evidence of nucleation and condensation of products related to the oxidation of different biogenic emissions. Particles from 5 nm to 50 nm in diameter evolved during the afternoon and early evening associated with variations in isoprene. Late in the evening the α‐ and β‐pinene mixing ratios and the aerosol particle volume increased. Soon after, there was a sharp increase in RO2H/H2O2 that persisted until about 0100 LT. The initial increases in the pinenes and aerosols were strong and influenced by changes in winds. After 2200 LT, and into the early morning, the winds were relatively steady, and the α‐ and β‐pinene mixing ratios continually decreased. The decay of α‐pinene is explained through reaction with O3. However, the addition of OH radicals from the reaction of terpenes with O3 is necessary to explain the observed rate of decay of β‐pinene. During the same time, the aerosol volume increased with the decrease in α‐ and β‐pinene. The volume increase was distributed 40∶60 between particles in a mode centered at 80–90 nm and particles &gt; 150 nm. The fine particle mass concentrations of the measured inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, and calcium) and organic ions (oxalate, formate, acetate, pyruvate, propionate) account for 25–30% of the total aerosol volume during the period (2.7 μm3 cm−3) indicating that the aerosol volume increase was due to unidentified species. Assuming that the increase in the aerosol was the result of products from the oxidation of α‐ and β‐pinene, an aerosol mass yield of 13% is estimated. The concentrations of cloud condensation nuclei active at 0.2% supersaturation were enhanced by the appearance of the 80–90 nm mode pointing to at least some of these forest‐generated particles as being able to serve as nuclei for cloud droplets at common atmospheric supersaturations.