Fine Particle Mass Concentrations Research Articles

Particulate and Ionic Species Near Highway Traffic During Day and Night

Ambient air particulate concentrations were sampled using an RP2300 Sampler (RP 2300, Rupprecht and Patashnick, CO, USA) from March 4 to April 2, 2006, at a sampling site near highway traffic. However particles that have an aerodynamic diameter of less than 10 μm (0.01 mm) are called respiratory particulates or particulate matter (PM10). PM2.5 denotes fine particles with an aerodynamic diameter of less than 2.5 μm (Ohlstrom et al., 2000). Analysis results indicated that the average mass concentrations of fine particles (PM2.5) and inhalable particles (PM10) were 64.43 and 109.20 μ g/m3, respectively, during the day. The average mass concentrations of PM2.5 and PM10 were 69.45 and 110.46 μ g/m3 during the night. Average concentrations of major ionic species, NO2 −, NO3 −, SO4 2 −, and NH4 + during the day were 2.37, 9.16, 13.72, and 7.70 μ g/m3 in PM2.5 and 3.72, 16.42, 16.90, and 8.91 μ g/m3 in PM10. The corresponding values at night were 3.29, 11.77, 11.55, and 8.03 μ g/m3 in PM2.5 and 3.87, 18.13, 14.27, and 9.98 μ g/m3 in PM10. However, t-test results revealed that the concentrations of ionic species (Cl−, NO2 −, NH4 +, Mg2 +, and Ca2 +) in PM2.5 during the day did not differ significantly from those at night. T-test results revealed that the ionic species (NO3 −, SO4 2 −, Na+, and K+) concentrations in PM2.5 during the day differ, significantly from those at night. The concentrations of ionic species (Cl−, NO2 −, NO3 −, and NH4 +) in PM10 during the day did not differ significantly from those at night. The concentrations of ionic species (SO4 2 −, Na+, K+, Mg2 +, and Ca2 +) in PM10 during the day differed significantly from those at night. The concentration of Cl− in PM2.5 is negatively correlated (r = −0.62) with the temperature during the day at this site close to highway traffic. Furthermore, a comparison with previous results (Fang et al., 1999a) revealed that the average concentration of NO3 − increased by 32% and 46% in PM2.5 and PM10, respectively, during the day. Average concentrations of NO3 − were increased by 72% and 65% in PM2.5 and PM10, respectively, during the night. Average concentrations of SO4 2 − were decreased by 10% and 7% in PM2.5 and PM10, respectively, during the day. Finally, average concentrations of SO4 2 − were decreased by 72% and 62% in PM2.5 and PM10, respectively, during the night. This monitoring data may be helpful to establish baseline or background concentrations, which is essential for forensic investigations.

Effect of Meteorological Parameters on Fine and Coarse Particulate Matter Mass Concentration in a Coal-Mining Area in Zonguldak, Turkey

In this work, the effect of meteorological parameters and local topography on mass concentrations of fine (PM2.5) and coarse (PM2.5–10) particles and their seasonal behavior was investigated. A total of 236 pairs of samplers were collected using an Anderson Dichotomous sampler between December 2004 and October 2005. The average mass concentrations of PM2.5, PM2.5–10, and particulate matter less than 10 μm in aerodynamic diameter (PM10) were found to be 29.38, 23.85, and 53.23 μ/m3, respectively. The concentrations of PM2.5 and PM10 were found to be higher in heating seasons (December to May) than in summer The increase of relative humidity, cloudiness, and lower temperature was found to be highly related to the increase of particulate matter (PM) episodic events. During non-rainy days, the episodic events for PM2.5 and PM10 were increased by 30 and 10.7%, respectively. This is a result of the extensive use of fuel during winter for heating purposes and also because of stagnant air masses formed because of low temperature and low wind speed over the study area.

Effects of chlorine and sulphur on particle formation in wood combustion performed in a laboratory scale reactor

Fine particle formation in wood combustion was studied in a laboratory scale laminar flow reactor at various flue gas chlorine and sulphur concentrations. Aerosol samples were quenched at around 850 °C using a porous tube diluter. Fine particle number concentrations, mass concentrations, size distributions and chemical compositions were measured. In addition, flue gas composition, including SO 2 and HCl, was monitored. Experimental results were interpreted by thermodynamic equilibrium calculations. Addition of HCl clearly raised fine particle mass concentration (PM1.0) which was because of increased release of ash-forming material to fine particles. Especially the release of K, Na, Zn and Cd to fine particles increased. These species form chlorides which apparently increases their volatilization from the fuel. When a sufficient amount of SO 2 was supplied in a chlorine rich combustion (S/Cl molar ratio from 4.7 to 7.5), most of the HCl stayed in the gas phase, release of ash-forming elements decreased and also fine particle concentrations dropped significantly. The sulphation of alkali metals is suggested to play a key role in the observed decrease in the fine particle concentration. It seems that the formation of sulphates leads to alkali metal retention in the coarse particle fraction.

The Impact of Secondary Particles on the Association between Ambient Ozone and Mortality

BackgroundAlthough several previous studies have found a positive association between ambient ozone and mortality, the observed effect may be confounded by other secondary pollutants that are produced concurrently with ozone.ObjectivesWe addressed the question of whether the ozone–mortality relationship is entirely a reflection of the adverse effect of ozone, or whether it is, at least in part, an effect of other secondary pollutants.MethodsSeparate time-series models were fit to 3–6 years of data between 2000 and 2005 from 18 U.S. communities. The association between nonaccidental mortality was examined with ozone alone and with ozone after adjustment for fine particle mass, sulfate, organic carbon, or nitrate concentrations. The effect estimates from each of these models were pooled using a random-effects meta-analysis to obtain an across-community average.ResultsWe found a 0.89% [95% confidence interval (CI), 0.45–1.33%] increase in nonaccidental mortality with a 10-ppb increase in same-day 24-hr summertime ozone across the 18 communities. After adjustment for PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) mass or nitrate, this estimate decreased slightly; but when adjusted for particle sulfate, the estimate was substantially reduced to 0.58% (95% CI, –0.33 to 1.49%).ConclusionsOur results demonstrate that the association between ozone and mortality is confounded by particle sulfate, suggesting that some secondary particle pollutants could be responsible for part of the observed ozone effect.

COMBUSTION AEROSOLS FROM MUNICIPAL WASTE INCINERATION—EFFECT OF FUEL FEEDSTOCK AND PLANT OPERATION

Combustion aerosols were measured in a 22 MW (thermal energy) municipal waste incinerator. Different types of waste fractions were added to a base-load waste and the effect on aerosol formation was measured. The waste fractions applied were: PVC plastic, pressure-impregnated wood, shoes, salt (NaCl), batteries, and automotive shredder waste. Also, runs with different changes in the operational conditions of the incinerator were made. Mass-based particle size distributions were measured using a cascade impactor and the number-based size distributions were measured using a Scanning Mobility Particle Sizer. The plant is equipped with flue gas cleaning and the penetration through this was determined. The particle morphology was investigated by Transmission Electron Microscopy (TEM) and chemical analysis of the aerosol particles was made by Energy Dispersive X-ray Spectroscopy (EDS). The mass-based particle size distribution was bimodal with a fine mode peak around 0.4 µm and a coarse mode peak around 100 µm. The addition of NaCl, shredder waste, and impregnated wood increased the mass concentration of fine particles (aerodynamic diameter below 2.5 µm). In general the mass concentration was stable and close to the reference PM2.5-value of 252 ± 21 mg/m3 (std.T,P). The total number concentration deviated during runs and between runs spanning from 43 · 106 to 87 · 106 #/cm3(std.T,P). The aerosols formed were mixtures of dense and aggregated particles in all tests. The fine particles are mainly composed by alkali salts, zinc, and lead. The heavy metals Cu, Cd, Hg, and Pb are significantly enriched in the fine particles.

Experimental exposure to wood smoke: effects on airway inflammation and oxidative stress

Background:Particulate air pollution affects cardiovascular and pulmonary disease and mortality. A main hypothesis about the mechanisms involved is that particles induce inflammation in lower airways, systemic inflammation and oxidative stress.Objectives:To...

Annoyance due to air pollution in Europe

Annoyance due to air pollution is a subjective score of air quality, which has been incorporated into the National Environmental monitoring of some countries. The objectives of this study are to describe the variations in annoyance due to air pollution in Europe and its individual and environmental determinants. This study took place in the context of the European Community Respiratory Health Survey II (ECRHS II) that was conducted during 1999-2001. It included 25 centres in 12 countries and 7867 randomly selected adults from the general population. Annoyance due to air pollution was self-reported on an 11-point scale. Annual mean mass concentration of fine particles (PM(2.5)) and its sulphur (S) content were measured in 21 centres as a surrogate of urban air pollution. Forty-three per cent of participants reported moderate annoyance (1-5 on the scale) and 14% high annoyance (> or =6) with large differences across centres (2-40% of high annoyance). Participants in the Northern European countries reported less annoyance. Female gender, nocturnal dyspnoea, phlegm and rhinitis, self-reported car and heavy vehicle traffic in front of the home, high education, non-smoking and exposure to environmental tobacco smoke were associated with higher annoyance levels. At the centre level, adjusted means of annoyance scores were moderately associated with sulphur urban levels (slope 1.43 microg m(-3), standard error 0.40, r = 0.61). Annoyance due to air pollution is frequent in Europe. Individuals' annoyance may be a useful measure of perceived ambient quality and could be considered a complementary tool for health surveillance.

Aerosol characteristics and surface radiative forcing components during a dust outbreak in Gwangju, Republic of Korea

Atmospheric surface aerosol radiative forcing (SARF) DeltaF, forcing efficiency DeltaF(e) and fractional forcing efficiency DeltaFF(e) evaluated from cloud-screened narrowband spectral and thermal-offset-corrected radiometric observations during the Asia dust outbreak episodes in Gwangju, Republic of Korea are reported in this study. Columnar aerosol optical properties (aerosol optical depth (AOD), tau (alambda), Angstrom exponent alpha, mass concentration of fine and coarse mode particles) were also reported for the station between January 2000 and May 2001 consisting of 211cloud-free days. Results indicate that majority of the AOD were within the range 0.25-0.45 while some high aerosol events in which AODs > or = 0.6 were observed during the severe dust episodes. For example, AOD increases from annual average value of 0.34 +/- 0.13 at 501 nm to values >0.60 during the major dust events of March 27-30 and April 7-9, 2000, respectively. The alpha (501-870 nm) which is often used as a qualitative indicator of aerosol particle size had values ranging from 0.01 to 1.77. The diurnal forcing efficiency DeltaDF(e) at Gwangju was estimated to be -81.10 +/- 5.14 W m (-2)/tau (501 nm) and -47.09 +/- 2.20 W m (-2)/tau (501 nm) for the total solar broadband and visible band pass, respectively while the fractional diurnal forcing efficiency DeltaFDF(e) were -15.8 +/- 0.64%/tau (501 nm) and -22.87 +/- 1.13%/tau (501 nm) for the same band passes. Analyses of the 5-day air-mass back trajectories were further developed for Gwangju in order to classify the air-mass and types of aerosol reaching the site during the Asia dust episodes.

Characterization and Mapping of Very Fine Particles in an Engine Machining and Assembly Facility

Very fine particle number and mass concentrations were mapped in an engine machining and assembly facility in the winter and summer. A condensation particle counter (CPC) was used to measure particle number concentrations in the 0.01 μ m to 1 μ m range, and an optical particle counter (OPC) was used to measure particle number concentrations in 15 channels between 0.3 μ m and 20 μ m. The OPC measurements were used to estimate the respirable mass concentration. Very fine particle number concentrations were estimated by subtracting the OPC particle number concentrations from 0.3 μ m to 1 μ m from the CPC number concentrations. At specific locations during the summer visit, an electrical low pressure impactor was used to measure particle size distribution from 0.07 μ m to 10 μ m in 12 channels. The geometric mean ratio of respirable mass concentration estimated from the OPC to the gravimetrically measured mass concentration was 0.66 with a geometric standard deviation of 1.5. Very fine particle number concentrations in winter were substantially greater where direct-fire natural gas heaters were operated (7.5 × 105 particles/cm3) than where steam was used for heat (3 × 105 particles/cm3). During summer when heaters were off, the very fine particle number concentrations were below 105 particles/cm3, regardless of location. Elevated very fine particle number concentrations were associated with machining operations with poor enclosures. Whereas respirable mass concentrations did not vary noticeably with season, they were greater in areas with poorly fitting enclosures (0.12 mg/m3) than in areas where state-of-the-art enclosures were used (0.03 mg/m3). These differences were attributed to metalworking fluid mist that escaped from poorly fitting enclosures. Particles generated from direct-fire natural gas heater operation were very small, with a number size distribution modal diameter of less than 0.023 μ m. Aerosols generated by machining operations had number size distributions modes in the 0.023 μ m to 0.1 μ m range. However, multiple modes in the mass size distributions estimated from OPC measurements occurred in the 2–20 μ m range. Although elevated, very fine particle concentrations and respirable mass concentrations were both associated with poorly enclosed machining operations; the operation of the direct-fire natural gas heaters resulted in the greatest very fine particle concentrations without elevating the respirable mass concentration. These results suggest that respirable mass concentration may not be an adequate indicator for very fine particle exposure.

Springtime soluble particles in a suburban area of Taichung in central Taiwan

Continuous measurements of concentrations of soluble species between fine and coarse particles were made using a RP 2300 sampler to characterize springtime particulate pollutants in Shalu, a suburban area of Taichung, Taiwan. Particulate matter was closely observed from March 4 to April 2, 2006. The characteristics of ambient particulates were investigated during the winter monsoon period, the weak winter monsoon period and the non-winter monsoon period. The wind speed influenced the ratio of the mass concentration of coarse particles to that of fine particles. The ratio was high during the strong winter monsoon because the coarse particles were re-suspended by high wind speed. In contrast, the low ratio was associated with the accumulation of local anthropogenic particles in a stagnant atmosphere in the non-winter monsoon period. The increases in the concentrations of soluble SO 4 2− and NO 3 − species were associated with the long-range transport of pollutants from the Asian Continent and local urban pollution emissions, respectively. Factor analysis was performed on the measurements to determine the variances of the identified sources among the three atmospheric conditions. The deviations from the seawater Cl −/Na + ratio of 1.16 in the coarse particles indicated the notable deficit of chloride. A large amount of air pollutants was transported by airflow during a dust event: the mass concentrations of fine particles and coarse particles in a dust event were 30% and 160% higher than those in a non-dust event, respectively.

Daily mortality and particulate matter in different size classes in Erfurt, Germany

The link between elevated concentrations of ambient particulate matter (PM) and increased mortality has been investigated in numerous studies. Here we analyzed the role of different particle size fractions with respect to total and cardio-respiratory mortality in Erfurt, Germany, between 1995 and 2001. Number concentrations (NC) of PM were measured using an aerosol spectrometer consisting of a Differential Mobility Particle Sizer and a Laser Aerosol Spectrometer to characterize particles between 0.01 and 0.5 and between 0.1 and 2.5 microm, respectively. We derived daily means of particle NC for ultrafine (0.01-0.1 microm) and for fine particles (0.01-2.5 microm). Assuming spherical particles of a constant density, we estimated the mass concentrations (MC) of particles in these size ranges. Concurrently, data on daily total and cardio-respiratory death counts were obtained from local health authorities. The data were analyzed using Poisson Generalized Additive Models adjusting for trend, seasonality, influenza epidemics, day of the week, and meteorology using smooth functions or indicator variables. We found statistically significant associations between elevated ultrafine particle (UFP; diameter: 0.01-0.1 microm) NC and total as well as cardio-respiratory mortality, each with a 4 days lag. The relative mortality risk (RR) for a 9748 cm(-3) increase in UFP NC was RR=1.029 and its 95% confidence interval (CI)=1.003-1.055 for total mortality. For cardio-respiratory mortality we found: RR=1.031, 95% CI: 1.003-1.060. No association between fine particle MC and mortality was found. This study shows that UFP, representing fresh combustion particles, may be an important component of urban air pollution associated with health effects.

Characterization of aerosol pollution events in France using ground-based and POLDER-2 satellite data

Abstract. We analyze the relationship between daily fine particle mass concentration (PM2.5) and columnar aerosol optical thickness derived from the Polarization and Directionality of Earth's Reflectances (POLDER) satellite sensor. The study is focused over France during the POLDER-2 lifetime between April and October 2003. We have first compared the POLDER derived aerosol optical thickness (AOT) with integrated volume size distribution derived from ground-based Sun Photometer observations. The good correlation (R=0.72) with sub-micron volume fraction indicates that POLDER derived AOT is sensitive to the fine aerosol mass concentration. Considering 1974 match-up data points over 28 fine particle monitoring sites, the POLDER-2 derived AOT is fairly well correlated with collocated PM2.5 measurements, with a correlation coefficient of 0.55. The correlation coefficient reaches a maximum of 0.80 for particular sites. We have analyzed the probability to find an appropriate air quality category (AQC) as defined by U.S. Environmental Protection Agency (EPA) from POLDER-2 AOT measurements. The probability can be up to 88.8% (±3.7%) for the "Good" AQC and 89.1% (±3.6%) for the "Moderate" AQC.

Spectral aerosol optical depth variation with different types of aerosol at Gwangju, Korea

Simultaneous ground-based measurements of aerosol chemical composition and atmospheric aerosol optical depth (AOD) in the UV and visible regions were carried out at Gwangju (35.13°N, 126.50°E), Korea during a biomass burning period, October 4–November 12, 2002. An Asian dust event and biomass burning events were observed during the study period. The correlation coefficients ( R) between AOD and PM 2.5 and PM 10 mass concentration during the study period are 0.58±0.15 and 0.52±0.14, respectively. Aerosol optical properties (AOD and Ångström exponent) and chemical characteristics were presented for selected days and their impacts on aerosol loading were examined. Both fine and coarse mode particle mass concentrations increased on biomass burning day resulting in high AOD values. The simultaneous occurrence of Asian dust and biomass burning resulted in the highest AOD of 1.20 at 311 nm and the lowest Ångström exponent of 0.42 in the visible range. When both transported urban pollutants and land dust aerosols affected the air quality over the study area, AOD and surface PM mass concentration increased 18–60% and 230–890%, respectively.

Estimation of the seasonal variation of particulate nitrate and sensitivity to the emission changes in the greater Seoul area

Seasonal variation of fine particulate nitrate and sensitivity of fine particle mass concentration to the emission changes of VOCs and NO x were estimated in the greater Seoul area. SBOX, a photochemical box model was used to obtain the total nitric acid (HNO 3 T) concentration, and SCAPE2, a gas/particle equilibrium model was used to determine the partitioning of nitric acid/nitrate and particulate water content. Most HNO 3 T existed as nitrate except in summer (∼60%) since there was enough ammonia to form particulate ammonium nitrate. In summer, high temperature was favorable to gaseous nitric acid. Also, because of average relative humidity (RH) higher than the deliquescence points of most salts, water content in summer was higher than those in other seasons by a factor of two. For all seasons, fine particle mass concentration (the sum of ion concentrations and water content) increased until considerable amount of NO x emissions was reduced. This phenomenon is a typical example of the so-called ‘NO x disbenefits’ that has been discussed in relation to the abatement of ozone pollution.

Risk assessment of exposure to indoor aerosols associated with Chinese cooking

Cooking is an important source of indoor aerosols in residential homes and buildings with non-smokers, and thus has public health implications. However, limited information is currently available in the published literature on the physical and chemical characteristics of aerosols produced by gas cooking. Consequently, a comprehensive study was carried out to investigate the physical (number and mass concentrations and size distributions) and chemical (metals) properties in a typical Chinese food stall in Singapore where stir-frying in a wok is the most common cooking method using gas stove. To assess the contribution of cooking activities to indoor particle concentrations, aerosol measurements were performed in two distinct time periods, i.e., during cooking and non-cooking hours. The average mass concentrations of fine particles (PM 2.5) and metals increased by a factor of 12 and 11, respectively, from 26.7 and 1.5 μg m −3 during non-cooking hours to 312.4 and 15.6 μg m −3 during cooking hours. The average number concentration was also elevated by a factor of 85, from 9.1×10 3 cm −3 during non-cooking hours to 7.7×10 5 cm −3 during cooking hours. Real-time particle measurements showed that about 80% of the particles associated with cooking are ultrafine particles in terms of particle counts. To evaluate the potential health threat due to inhalation of air pollutants released from gas cooking, the health risk estimates based on exposure and dose–response assessments of metals were calculated for a maximally exposed individual. The findings indicate that the indoor air quality existing at the food stall may pose adverse health effects over long-term exposure to cooking emissions.

Experimental Exposure to Wood-Smoke Particles in Healthy Humans: Effects on Markers of Inflammation, Coagulation, and Lipid Peroxidation

Particulate air pollution is known to increase cardiovascular morbidity and mortality. Proposed mechanisms underlying this increase include effects on inflammation, coagulation factors, and oxidative stress, which could increase the risk of coronary events and atherosclerosis. The aim of this study was to examine whether short-term exposure to wood smoke affects markers of inflammation, blood hemostasis, and lipid peroxidation in healthy humans. Thirteen subjects were exposed to wood smoke and clean air in a chamber during two 4-h sessions, 1 wk apart. The mass concentrations of fine particles at wood smoke exposure were 240–280 μg/m3, and number concentrations were 95,000–180,000/cm3. About half of the particles were ultrafine (< 100 nm). Blood and urine samples were taken before and after the experiment. Exposure to wood smoke increased the levels of serum amyloid A, a cardiovascular risk factor, as well as factor VIII in plasma and the factor VIII/von Willebrand factor ratio, indicating a slight effect on the balance of coagulation factors. Moreover, there was an increased urinary excretion of free 8-iso-prostaglandin2α, a major F2-isoprostane, though this was based on nine subjects only, indicating a temporary increase in free radical-mediated lipid peroxidation. Thus, wood-smoke particles at levels that can be found in smoky indoor environments seem to affect inflammation, coagulation, and possibly lipid peroxidation. These factors may be involved in the mechanisms whereby particulate air pollution affects cardiovascular morbidity and mortality. The exposure setup could be used to establish which particle characteristics are critical for the effects.

Effect of Chlorine and Sulfur on Fine Particle Formation in Pilot-Scale CFBC of Biomass

Behavior of chlorine and sulfur is critical on the formation of fine particles (here particles smaller than one micrometer, PM1.0) during combustion. In this investigation, we studied experimentally fine particle formation in a pilot-scale circulating fluidized bed reactor during combustion of bark and pulp and paper mill sludge. The effect of chlorine and sulfur on fine particle formation was investigated by adding HCl and SO2 into the reactor. Fine fly ash particles were formed from alkali species that were released from the fuel to the gas phase. In low-HCl conditions, alkali species reacted readily with silicates, and therefore, a large fraction of alkalis was retained in the bottom ash. Consequently, fine particle concentrations in the flue gas were relatively low. In this case, fine particles were both alkali metal chlorides and sulfates. HCl addition increased the concentration of fine particles considerably due to gas phase reactions between alkali metal species and HCl. Alkali metal chlorides that were formed condensed producing large mass concentrations of fine alkali metal chloride particles. Due to extensive alkali metal chloride formation, significantly less alkalis reacted with silicates and ended up in the bottom ash than when HCl concentration was low. Further SO2 addition transformed some of the chlorides into sulfates in the fine particle mode. At the same time, the total fine particle concentration decreased, possibly due to formation of coarse mixed K−Ca−sulfate ash particles.

Fine Particulate Formation During Switchgrass/Coal Cofiring

Experiments to examine the effects of biomass/coal cofiring on fine particle formation were performed in the Sandia Multi-Fuel Combustor using fuels of pure coal, three combinations of switchgrass and coal, and pure switchgrass. For this work, fine particles with aerodynamic diameter between 10 nm and 1 μm were examined. A constant solid-fuel thermal input of 8 kW was maintained. The combustion products were cooled from 1200 to 420°C during passage through the 4.2 m long reactor to simulate the temperatures experienced in the convection pass of a boiler. Fine particle number densities, mass concentrations, and total integrated number and mass concentrations at the reactor exit were determined using a scanning mobility particle sizer. The fine particle number concentrations for cofiring were much higher than those achieved with dedicated coal combustion. However, the total integrated mass concentration of particles remained essentially constant for all levels of cofiring from 0% coal to 100% coal. The constant mass concentration is significant because pending environmental regulations are likely to be based on particle mass rather than particle size.

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

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

Validation of a Method for Estimating Long‐Term Exposures Based on Short‐Term Measurements

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 99th 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.