Results of An Indoor Size Fractionated PM School Sampling Program in Libby, Montana

Libby, Montana is the only PM_2.5 nonattainment area in the western United States with the exceptions of parts of southern California. During January through March 2005, a particulate matter (PM) sampling program was conducted within Libby’s elementary and middle schools to establish baseline indoor PM concentrations before a wood stove change-out program is implemented over the next several years. As part of this program, indoor concentrations of PM mass, organic carbon (OC), and elemental carbon (EC) in five different size fractions (>2.5, 1.0–2.5, 0.5–1.0, 0.25–0.5, and <0.25 μm) were measured. Total measured PM mass concentrations were much higher inside the elementary school, with particle size fraction (>2.5, 0.5–1.0, 0.25–0.5, and <0.25 μm) concentrations between 2 and 5 times higher when compared to the middle school. The 1.0–2.5 μm fraction had the largest difference between the two sites, with elementary school concentrations nearly 10 times higher than the middle school values. The carbon component for the schools’ indoor PM was found to be predominantly composed of OC. Measured total OC and EC concentrations, as well as concentrations within individual size fractions, were an average of two to five times higher at the elementary school when compared to the middle school. For the ultrafine fraction (<0.25), EC concentrations were similar between each of the schools. Despite the differences in concentrations between the schools at the various fraction levels, the OC/EC ratio was determined to be similar.     

Apportionment of the airborne PM10 in Spain. Episodes of potential negative impact for human health

The particulate matter with an aerodynamic diameter less than or equal to 10 and 2.5 microns respectively (PM10 and PM2.5) constitutes one of the main air pollutants, which is currently regulated in Europe through Directive 2008/50/EC due to its proven harmful effects on human health. In this paper, the airborne PM10 samples collected in Zaragoza city during 2001-2009 were apportioned by statistical tools based on principal component analysis with absolute principal component scores (PCA-APCS). PM10 samples were characterized regarding their concentrations of polycyclic aromatic hydrocarbons (PAH) and water-soluble ions. PAH were analyzed by gas chromatography-mass spectrometry-mass spectrometry detection (GC-MS-MS) and ions were analyzed by ion chromatography. A total of five factors were identified by PCA-APCS corresponding to different anthropogenic and natural sources. This work was focused on analyzing in more detail those samples involving higher negative impact on human health, in particular, PM10 samples exceeding the daily PM10 limit value of 50 μg m(-3) according to Directive 2008/50/EC and samples with concentrations of benzo[a]pyrene (BaP) higher than the upper assessment threshold (BaP > 0.6 ng m(-3)) established by the Directive 2004/107/EC. Most of the exceedances of the daily PM10 limit value were associated with direct and indirect North-African long-range transport. During these exceedances, it was observed that anthropogenic pollution sources slightly decreased with regard to the natural sources. This indicated that episodes of high PM10 could have a natural origin associated with long-range transport from the African continent. On the contrary, those exceedances with regional contribution and samples with BaP concentrations higher than 0.6 ng m(-3) showed an important contribution of anthropogenic pollution sources increasing their negative impact on human health.     

Spatial & temporal variations of PM10 and particle number concentrations in urban air

The size of particles in urban air varies over four orders of magnitude (from 0.001 μm to 10 μm in diameter). In many cities only particle mass concentrations (PM10, i.e. particles <10 μm diameter) is measured. In this paper we analyze how differences in emissions, background concentrations and meteorology affect the temporal and spatial distribution of PM10 and total particle number concentrations (PNC) based on measurements and dispersion modeling in Stockholm, Sweden. PNC at densely trafficked kerbside locations are dominated by ultrafine particles (<0.1 μm diameter) due to vehicle exhaust emissions as verified by high correlation with NOx. But PNC contribute only marginally to PM10, due to the small size of exhaust particles. Instead wear of the road surface is an important factor for the highest PM10 concentrations observed. In Stockholm, road wear increases drastically due to the use of studded tires and traction sand on streets during winter; up to 90% of the locally emitted PM10 may be due to road abrasion. PM10 emissions and concentrations, but not PNC, at kerbside are controlled by road moisture. Annual mean urban background PM10 levels are relatively uniformly distributed over the city, due to the importance of long range transport. For PNC local sources often dominate the concentrations resulting in large temporal and spatial gradients in the concentrations. Despite these differences in the origin of PM10 and PNC, the spatial gradients of annual mean concentrations due to local sources are of equal magnitude due to the common source, namely traffic. Thus, people in different areas experiencing a factor of 2 different annual PM10 exposure due to local sources will also experience a factor of 2 different exposure in terms of PNC. This implies that health impact studies based solely on spatial differences in annual exposure to PM10 may not separate differences in health effects due to ultrafine and coarse particles. On the other hand, health effect assessments based on time series exposure analysis of PM10 and PNC, should be able to observe differences in health effects of ultrafine particles versus coarse particles.     

Indoor and outdoor PM mass and number concentrations at schools in the Athens area

Simultaneous indoor and outdoor PM₁₀ and PM_2.5 concentration measurements were conducted in seven primary schools in the Athens area. Both gravimetric samplers and continuous monitors were used. Filters were subsequently analyzed for anion species. Moreover ultrafine particles number concentration was monitored continuously indoors and outdoors. Mean 8-hr PM₁₀ concentration was measured equal to 229 ± 182 μg/m³ indoors and 166 ± 133 μg/m³ outdoors. The respective PM_2.5 concentrations were 82 ± 56 μg/m³ indoors and 56 ± 26 μg/m³ outdoors. Ultrafine particles 8-h mean number concentration was measured equal to 24,000 ± 17,900 particles/cm³ indoors and 32,000 ± 14,200 particles/cm³ outdoors. PM₁₀ outdoor concentrations exhibited a greater spatial variability than the corresponding PM_2.5 ones. I/O ratios were close or above 1.00 for PM₁₀ and PM_2.5 and smaller than 1.00 for ultrafine particles. Very high I/O ratios were observed when intense activities took place. The initial results of the chemical analysis showed that accounts for the 6.6 ± 3.5% of the PM₁₀ and for the 3.1 ± 1.4%.The corresponding results for PM_2.5 are 12.0 ± 7.7% for and 3.1 ± 1.9% for . PM_2.5 indoor concentrations were highly correlated with outdoor ones and the regression line had the largest slope and a very low intercept, indicative of no indoor sources of fine particulate . The results of the statistical analysis of indoor and outdoor concentration data support the use of as a proper surrogate for indoor PM of outdoor origin.     

Characterization of PM10 and PM2.5 and associated heavy metals at the crossroads and urban background site in Zabrze, Upper Silesia, Poland, during the smog episodes

The concentrations of seven heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, and Pb) associated with PM10 and PM2.5 at the crossroads and the background sites have been studied in Zabrze, Poland, during smog episodes. Although the background level was unusually elevated due to both high particulate emission from the industrial and municipal sources and smog favorable meteorological conditions, significant increase of the concentration of PM2.5 and PM10 as well as associated heavy metals in the roadside air compared to the urban background has been documented. The average daily difference between the roadside and corresponding urban background aerosol concentration was equal to 39.5 μg m^???3 for PM10 and 41.2 μg m^???3 for PM2.5. The highest levels of the studied metals in Zabrze appeared for iron carried by PM10 particles: 1,706 (background) and 28,557 ng m^???3 (crossroads). The lowest concentration level (in PM10) has been found for cadmium: 7 and 77 ng m^???3 in the background and crossroads site, respectively. Also the concentrations of heavy metals carried by the fine particles (PM2.5) were very high in Zabrze during the smog episodes. Concentrations of all studied metals associated with PM10 increased at the roadside compared to the background about ten times (one order) while metals contained in PM2.5 showed two to three times elevated concentrations (except Fe—five times and Cr—no increase).     

Characteristics of aerosol types during large-scale transport of air pollution over the Yellow Sea region and at Cheongwon,Korea, in 2008

Episodes of large-scale transport of airborne dust and anthropogenic pollutant particles from different sources in the East Asian continent in 2008 were identified by National Oceanic and Atmospheric Administration satellite RGB (red, green, and blue)-composite images and the mass concentrations of ground level particulate matter. These particles were divided into dust, sea salt, smoke plume, and sulfate by an aerosol classification algorithm. To analyze the aerosol size distribution during large-scale transport of atmospheric aerosols, aerosol optical depth (AOD) and fine aerosol weighting (FW) of moderate imaging spectroradiometer aerosol products were used over the East Asian region. Six episodes of massive airborne dust particles, originating from sandstorms in northern China, Mongolia, and the Loess Plateau of China, were observed at Cheongwon. Classified dust aerosol types were distributed on a large-scale over the Yellow Sea region. The average PM10 and PM2.5 ratio to the total mass concentration TSP were 70% and 15%, respectively. However, the mass concentration of PM2.5 among TSP increased to as high as 23% in an episode where dust traveled in by way of an industrial area in eastern China. In the other five episodes of anthropogenic pollutant particles that flowed into the Korean Peninsula from eastern China, the anthropogenic pollutant particles were largely detected in the form of smoke over the Yellow Sea region. The average PM10 and PM2.5 ratios to TSP were 82% and 65%, respectively. The ratio of PM2.5 mass concentrations among TSP varied significantly depending on the origin and pathway of the airborne dust particles. The average AOD for the large-scale transport of anthropogenic pollutant particles in the East Asian region was measured to be 0.42 ± 0.17, which is higher in terms of the rate against atmospheric aerosols as compared with the AOD (0.36 ± 0.13) for airborne dust particles with sandstorms. In particular, the region ranging from eastern China, the Yellow Sea, and the Korean Peninsula to the Korea East Sea was characterized by high AOD distributions. In the episode of anthropogenic polluted aerosols, FW averaged 0.63 ± 0.16, a value higher than that in the episode of airborne dust particles (0.52 ± 0.13) with sandstorms, showing that fine anthropogenic pollutant particles contribute greatly to atmospheric aerosols in East Asia.     

Chemical Composition and Sources of PM10 and PM2.5 Aerosols in Guangzhou, China

Aerosol samples of PM10 and PM2.5 are collected in summertime at four monitoring sites in Guangzhou, China. The concentrations of organic and elemental carbons (OC/EC), inorganic ions, and elements in PM10 and PM2.5 are also quantified. Our study aims to: (1) characterize the particulate concentrations and associated chemical species in urban atmosphere (2) identify the potential sources and estimate their apportionment. The results show that average concentration of PM2.5 (97.54 μg m⁻³) in Guangzhou significantly exceeds the National Ambient Air Quality Standard (NAAQS) 24-h average of 65 μg m⁻³. OC, EC, Sulfate, ammonium, K, V, Ni, Cu, Zn, Pb, As, Cd and Se are mainly in PM2.5 fraction of particles, while chloride, nitrate, Na, Mg, Al, Fe, Ca, Ti and Mn are mainly in PM2.5-10 fraction. The major components such as sulfate, OC and EC account for about 70–90% of the particulate mass. Enrichment factors (EF) for elements are calculated to indicate that elements of anthropogenic origins (Zn, Pb, As, Se, V, Ni, Cu and Cd) are highly enriched with respect to crustal composition (Al, Fe, Ca, Ti and Mn). Ambient and source data are used in the multi-variable linearly regression analysis for source identification and apportionment, indicating that major sources and their apportionments of ambient particulate aerosols in Guangzhou are vehicle exhaust by 38.4% and coal combustion by 26.0%, respetively.     

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

Atmospheric surface aerosol radiative forcing (SARF) ΔF, forcing efficiency ΔF_e and fractional forcing efficiency ΔFF_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), τ _aλ, Angstrom exponent α, 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 ≥ 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 α _{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 ΔDF_e at Gwangju was estimated to be −81.10 ± 5.14 W m ⁻²/τ _{501 nm} and −47.09 ± 2.20 W m ⁻²/τ _{501 nm} for the total solar broadband and visible band pass, respectively while the fractional diurnal forcing efficiency ΔFDF_e were −15.8 ± 0.64%/τ _{501 nm} and −22.87 ± 1.13%/τ _{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.     

Local and regional air pollution in Ireland during an intensive aerosol measurement campaign

An intensive two month measurement campaign has been performed during a two year study of major component composition of urban PM10 and PM2.5 in Ireland (J. Yin, A. G. Allen, R. M. Harrison, S. G. Jennings, E. Wright, M. Fitzpatrick, T. Healy, E. Barry, D. Ceburnis and D. McCusker, Atmos. Res., 2005, 78(3-4), 149-165). Measurements included size-segregated mass, soluble ions, elemental carbon (EC) distributions, fine and coarse fraction organic carbon (OC) and major gases along with standard meteorological measurements. The study revealed that urban emissions in Ireland had mainly a local character and therefore were confined within a limited area of 20-30 km radius, without significantly affecting regional air quality. Gaseous measurements have shown that urban emissions in Ireland had clear, but fairly limited influence on the regional air quality due to favorable mixing conditions at higher wind speeds, in particular from the western sector. Size-segregated mass and chemical measurements revealed a clear demarcation size between accumulation and coarse modes at about 0.8 microm which was constant at all sites. Carbonaceous compounds at the urban site accounted for up to 90% of the particle mass in a size range of 0.066-0.61 microm. Nss SO4(2-) concentrations in PM2.5 were only slightly higher at the urban site compared to the rural or coastal sites, while NO3- and NH4+ concentrations were similar at the urban and coastal sites, but were a factor of 2 to 3 higher than at the rural site. OC was highly variable between the sites and revealed clear seasonal differences. Natural or biogenic OC component accounted for <10% in winter and up to 30% in summer of the PM2.5 OC at urban sites. A contribution of biogenic OC component to PM2.5 OC mass at rural site was dominant.     

Inorganic constituents of urban air pollution in the Lazio region (Central Italy)

A field study was carried out at six locations in the Lazio region (Central Italy) aimed at characterising atmospheric particulate matter (PM₁₀ and PM_2.5) from the point of view of the chemical composition and grain size distribution of the particles, the mixing properties of the atmosphere, the frequency and relevance of natural events. The combination of four different analytical techniques (ion chromatography, X-ray fluorescence and ICP for inorganic components, thermo-optical analysis for carbon compounds) yielded sound results in terms of characterisation of the air masses. During the first three months of the study (October–December 2004), many pollution events of natural (sea-salt or desert dust episodes) or anthropogenic nature were identified and characterised. More than 90% of the collected mass was identified by chemical analysis. The central role played by the mixing properties of the lower atmosphere when pollution events occurred was highlighted. The results show a major impact of primary anthropogenic pollutants on traffic stations and a homogeneous distribution of secondary pollutants over the regional area. An evaluation of the sources of PM and an identification of possible reliable tracers were obtained using a chemical fractionation procedure.