The PM2.5 and PM10 particles in urban areas of Taiwan

This study conducted an atmospheric aerosol sampling to measure the PM10 (particles < 10 microns in aerodynamic diameter) and PM2.5 (particles < 2.5 microns in aerodynamic diameter) mass concentrations from October 1996 to June 1997 in northern (Taipei), central (Taichung) and southern (Kaohsiung), the three largest cities of Taiwan. Seventy-eight samples were obtained to measure the mass concentrations of PM10 and PM2.5 from nine sampling sites. According to those results, the PM10 mass concentrations in Taipei, Taichung and Kaohsiung were 42.19, 60.99 and 77.10 micrograms/m3, respectively. The corresponding PM2.5 mass concentrations were 23.09, 39.97 and 48.47 micrograms/m3, respectively. The PM2.5 fraction accounted for 61-67% of the PM10 mass in central and southern Taiwan, but was lower (54-59%) in northern Taiwan. Some samples in which the PM2.5 fraction was overwhelmingly dominant could reach as high as 80-95% of the PM10 mass. In addition, the PM2.5, PM10 levels and PM2.5/PM10-2.5 (particles with aerodynamic diameters ranging from 2.5 to 10 microns) ratios in metropolitan Taiwan significantly fluctuated from site-to-site and over time. Moreover, ambient daily PM2.5 and PM10-2.5 mass concentrations did not correlate well with each other at most of the sampling sites, indicated that they originated from different kinds of sources and emitted variedly over time.     

The characteristic study of TSP, PM2.5-10 and PM2.5 in the rural site of central Taiwan.

The total suspended particle (TSP), PM2.5-10 (aerodynamic diameter less than 10 microns) and PM2.5 concentration (aerodynamic diameter less than 2.5 microns) concentrations were sampled by PS-1 and Universal sampler on the roof (25 m) of the Medical and Engineering Building in the campus of Hungkuang Institute of Technology (HKIT) which is located at a height of 500 m on Da Du Mountain. The results indicated that average TSP, PM2.5-10 and PM2.5 concentrations are 0.42, 0.34 and 0.019 mg/m3 in the day time, respectively and are 0.32, 0.26 and 0.017 mg/m3 in the night time, respectively. The ratios of PM2.5-10/TSP were from 76% to 85% and from 50% to 91% for day and night period, respectively. It indicated that the major composition in the total suspended particles was PM2.5-10 in the rural site. The relationship between TSP and PM2.5-10 is TSP = 1.16PM2.5-10 + 0.027 and TSP = 1.01 PM2.5-10 + 0.058 in the day and night time, respectively. The correlation coefficient (R2) is 0.98 and 0.97 for day and night period, respectively. The relationship between PM2.5-10 and PM2.5 is PM2.5 = 0.0005PM2.5-10 + 0.019 and PM2.5 = 0.037PM2.5-10 + 0.0076 in the day and night period, respectively. The correlation coefficient (R2) is 3E-5 and 0.67 for day and night period, respectively. The relationships between TSP, PM2.5-10, PM2.5 particle concentrations and wind speed (R2) in the day time are 0.71, 0.64, 0.43, respectively and are 0.83, 0.79, 0.57, respectively in the night time. The proposed reasons are that there are more activities caused by people (students) and natural living animals which absorbed some of the particles during the day time. Thus, the correlation coefficients for the night time are better than those of day time. The particle size distributions are both bimodel in the day and night time. The major peaks in the day time appear in the particle diameter between 0.031-0.056 micron and 3.16-5.62 microns in the day period and appear between 0.017-0.031 micron and 1.78-3.16 microns in the night period. The results indicate that the particle size distribution in the day time tends to be of larger particle size mode than the night time.     

Hospital indoor PM10/PM2.5 and associated trace elements in Guangzhou, China

PM10 and PM2.5 samples were collected in the indoor environments of four hospitals and their adjacent outdoor environments in Guangzhou, China during the summertime. The concentrations of 18 target elements in particles were also quantified. The results showed that indoor PM2.5 levels with an average of 99 microg m(-3) were significantly higher than outdoor PM2.5 standard of 65 microg m(-3) recommended by USEPA [United States Environmental Protection Agency. Office of Air and Radiation, Office of Air Quality Planning and Standards, Fact Sheet. EPA's Revised Particulate Matter Standards, 17, July 1997] and PM2.5 constituted a large fraction of indoor respirable particles (PM10) by an average of 78% in four hospitals. High correlation between PM2.5 and PM10 (R(2) of 0.87 for indoors and 0.90 for outdoors) suggested that PM2.5 and PM10 came from similar particulate emission sources. The indoor particulate levels were correlated with the corresponding outdoors (R(2) of 0.78 for PM2.5 and 0.67 for PM10), demonstrating that outdoor infiltration could lead to direct transportation into indoors. In addition to outdoor infiltration, human activities and ventilation types could also influence indoor particulate levels in four hospitals. Total target elements accounted for 3.18-5.56% of PM2.5 and 4.38-9.20% of PM10 by mass, respectively. Na, Al, Ca, Fe, Mg, Mn and Ti were found in the coarse particles, while K, V, Cr, Ni, Cu, Zn, Cd, Sn, Pb, As and Se existed more in the fine particles. The average indoor concentrations of total elements were lower than those measured outdoors, suggesting that indoor elements originated mainly from outdoor emission sources. Enrichment factors (EF) for trace element were calculated to show that elements of anthropogenic origins (Zn, Pb, As, Se, V, Ni, Cu and Cd) were highly enriched with respect to crustal composition (Al, Fe, Ca, Ti and Mn). Factor analysis was used to identify possible pollution source-types, namely street dust, road traffic and combustion processes.     

Chemical characteristics of airborne particulate matter near major roads and at background locations in Macao, China

PM10 and PM2.5 samples were collected near major roads and at the background locations in Macao using a TEOM1400a+ACCU system. The chemical analysis of these particles indicated the presence of 36 elements, water-soluble ions and carbonaceous species. The greatest contributors to total PM10 and PM2.5 mass were OC, sulfate, nitrate, ammonium, EC, Na, Cl and crustal elements including Si, Ca, Al, Fe, K and Mg. Organic material is the largest single fraction of airborne particulate matter in Macao. It contributes 32.8-41.5% and 38.2-48.4% of PM10 and PM2.5 at the roadsides, and as high as 29.7% and 33.4-39.4% of PM10 and PM2.5 at background locations, respectively. EC contributes 3.7-7.8% and 8.0-12.9% of PM10 and PM2.5, and crustal material is 10.2-15.4% and 7.6-12.2% of PM10 and PM2.5 near major roads, respectively. The share of EC at background locations is much lower than that at the roadsides, however, the contribution of crustal material is the same in both locations. At the roadsides, secondary aerosols, including sulfate, nitrate and ammonium, account for 16.6-29.0% and 15.8-38.0% of the total PM10 and PM2.5, respectively, as compared to 29.1-36.2% and 23.2-33.8% of total PM10 and PM2.5, respectively, at background locations. In PM2.5, Na and Cl contribute 1-3%, while the average amount of these two elements increase to 1-15% of the total PM10 in Macao.     

Characteristics of PM10, SO2, NO(x) and O3 in ambient air during the dust storm period in Beijing

In this study, the hourly variations of the mass concentrations of PM10, SO2, NO(x) and O3 at three sampling sites were observed in Beijing during dust storm occurrence period in April 2000. The PM2.5 samples were simultaneously collected. By comparing the hourly variations of the pollutant concentrations before, during and after dust storm event and haze pollution episode, the variation characteristics of the mass concentrations of PM10, SO2, NO(x) and O3 during dust storm events were presented. The results show that the mass concentration of PM10 reached 1500 microg m(-3) during dust storm events on April 6 and 25, 2000, which was 5-10 times that of the non-dust weather conditions, and this period of high mass concentration of PM10 lasted for about 14 h, and then the concentration level prior to the dust event was recovered in 6-h time period. Due to the strong wind, the concentrations of SO2, NO(x), NO2 and O3 during dust storm period were maintained at low levels, which was significantly different from those on non-dust storm and haze pollution conditions. A lot of coarse particles as well as a very large amount of fine particles were contained in the atmospheric particulates during dust storm period, and the concentration level of PM2.5 was comparable to that during haze pollution episode. During the dust storm period, the PM2.5 concentration was approximately 230 microg m(-3), accounting for 30% of the total PM10 mass concentration, was four times that of non-dust weather conditions, and the crustal elements constituted about 66.4% of the chemical composition of PM2.5 while sulfate and nitrate contributed much less, which was quite different from the chemical composition of PM2.5 primarily constituted by sulfate, nitrate and organics on haze pollution day.     

Measurements of children's exposures to particles and nitrogen dioxide in Santiago, Chile

An exposure study of children (aged 10-12 years) living in Santiago, Chile, was conducted. Personal, indoor and outdoor fine and inhalable particulate matter (< 2.5 .m in diameter, PM2.5 and < 10 microm in diameter, PM10, respectively), and nitrogen dioxide (NO2) were measured during pilot (N = 8) and main (N = 20) studies, which were conducted during the winters of 1998 and 1999, respectively. For the main study, personal, indoor and outdoor 24-h samples were collected for five consecutive days. Similar mean personal, indoor and outdoor PM2.5 concentrations (69.5, 68.5 and 68.1 microg/m3, respectively) were found. However, for coarse particles (calculated as the difference between measured PM10 and PM2.5, PM2.5-10), indoor and outdoor levels (35.4 and 47.4 microg/m3) were lower than their corresponding personal exposures (76.3 microg/m3). Indoor and outdoor NO2 concentrations were comparable (35.8 and 36.9 ppb) and higher than personal exposures (25.9 ppb). Very low ambient indoor and personal O3 levels were found, which were mostly below the method's limit of detection (LOD). Outdoor particles contributed significantly to indoor concentrations, with effective penetration efficiencies of 0.61 and 0.30 for PM2.5 and PM2.5-10, respectively. Personal exposures were strongly associated with indoor and outdoor concentrations for PM2.5, but weakly associated for PM2.5-10. For NO2, weak associations were obtained for indoor-outdoor and personal-outdoor relationships. This is probably a result of the presence of gas cooking stoves in all the homes. Median I/O, P/I and P/O ratios for PM2.5 were close to unity, and for NO2 they ranged between 0.64 and 0.95. These ratios were probably due to high ambient PM2.5 and NO2 levels in Santiago, which diminished the relative contribution of indoor sources and subjects' activities to indoor and personal PM2.5 and NO2 levels.     

Indoor/outdoor relationships for PM2.5 and associated carbonaceous pollutants at residential homes in Hong Kong - case study

Six residences were selected (two roadside, two urban, and two rural) to evaluate the indoor-outdoor characteristics of PM(2.5) (aerodynamic diameter <2.5 microm) carbonaceous species in Hong Kong during March and April 2004. Twenty-minute-averaged indoor and outdoor PM(2.5) concentrations were recorded by DustTrak samplers simultaneously at each site for 3 days to examine diurnal variability of PM(2.5) mass concentrations and their indoor-to-outdoor (I/O) ratios. Daily (24-h average) indoor/outdoor PM(2.5) samples were collected on pre-fired quartz-fiber filters with battery-powered portable mini-volume samplers and analyzed for organic and elemental carbon (OC, EC) by thermal/optical reflectance (TOR) following the Interagency Monitoring of Protected Visual Environments (IMPROVE) protocol. The average indoor and outdoor concentrations of 24 h PM(2.5) were 56.7 and 43.8 microg/m(3), respectively. The short-term PM(2.5) profiles indicated that the penetration of outdoor particles was an important contributor to indoor PM(2.5), and a household survey indicated that daily activities were also sources of episodic peaks in indoor PM(2.5). The average indoor OC and EC concentrations of 17.1 and 2.8 microg/m(3), respectively, accounted for an average of 29.5 and 5.2%, respectively, of indoor PM(2.5) mass. The average indoor OC/EC ratios were 5.8, 9.1, and 5.0 in roadside, urban, and rural areas, respectively; while average outdoor OC/EC ratios were 4.0, 4.3, and 4.0, respectively. The average I/O ratios of 24 h PM(2.5), OC, and EC were 1.4, 1.8, and 1.2, respectively. High indoor-outdoor correlations (r(2)) were found for PM(2.5) EC (0.96) and mass (0.81), and low correlations were found for OC (0.55), indicative of different organic carbon sources indoors. A simple model implied that about two-thirds of carbonaceous particles in indoor air are originated from outdoor sources. PRACTICAL IMPLICATIONS: Indoor particulate pollution has received more attentions in Asia. This study presents a case study regarding the fine particulate matter and its carbonaceous compositions at six residential homes in Hong Kong. The characteristics and relationship of atmospheric organic and elemental carbon were discussed indoors and outdoors. The distribution of eight carbon fractions was first reported in indoor samples to interpret potential sources of indoor carbonaceous particles. The data set can provide significant scientific basis for indoor air quality and epidemiology study in Hong Kong and China.     

Characterizing air pollution in two low-income neighborhoods in Accra, Ghana

Sub-Saharan Africa has the highest rate of urban population growth in the world, with a large number of urban residents living in low-income "slum" neighborhoods. We conducted a study for an initial assessment of the levels and spatial and/or temporal patterns of multiple pollutants in the ambient air in two low-income neighborhoods in Accra, Ghana. Over a 3-week period we measured (i) 24-hour integrated PM(10) and PM(2.5) mass at four roof-top fixed sites, also used for particle speciation; (ii) continuous PM(10) and PM(2.5) at one fixed site; and (iii) 96-hour integrated concentration of sulfur dioxide (SO(2)) and nitrogen dioxide (NO(2)) at 30 fixed sites. We also conducted seven consecutive days of mobile monitoring of PM(10) and PM(2.5) mass and submicron particle count. PM(10) ranged from 57.9 to 93.6 microg/m(3) at the four sites, with a weighted average of 71.8 microg/m(3) and PM(2.5) from 22.3 to 40.2 microg/m(3), with an average of 27.4 microg/m(3). PM(2.5)/PM(10) ratio at the four fixed sites ranged from 0.33 to 0.43. Elemental carbon (EC) was 10-11% of PM(2.5) mass at all four measurement sites; organic matter (OM) formed slightly less than 50% of PM(2.5) mass. Cl, K, and S had the largest elemental contributions to PM(2.5) mass, and Cl, Si, Ca, Fe, and Al to coarse particles. SO(2) and NO(2) concentrations were almost universally lower than the US-EPA National Ambient Air Quality Standards (NAAQS), with virtually no variation across sites. There is evidence for the contributions from biomass and traffic sources, and from geological and marine non-combustion sources to particle pollution. The implications of the results for future urban air pollution monitoring and measurement in developing countries are discussed.     

Particulate matter exposure along designated bicycle routes in Vancouver, British Columbia

An instrumented bicycle was used to elucidate particulate matter exposures along bicycle routes passing through a variety of land uses over 14 days during summer and fall in a mid-latitude traffic dominated urban setting. Overall, exposures were low or comparable to those found in studies elsewhere (mean PM(2.5) and PM(10) concentrations over each daily bicycle traverse varied between 7-34 microg m(-3) and 26-77 microg m(-3) respectively). Meteorological factors were responsible for significant day-to-day variability with PM(2.5) positively correlated with air temperature, PM(10) negatively correlated with precipitation, and ultrafine particles negatively correlated with both air temperature and wind speed. On individual days, land use and proximity to traffic were factors significantly affecting exposure along designated bicycle routes. While concentrations of PM(2.5) were found to be relatively spatially uniform over the length of the study route, PM(10) showed a more heterogeneous spatial distribution. Specifically, construction sites and areas susceptible to the suspension of road dust have higher concentrations of coarse particles. Ultrafine particles were also heterogeneously distributed in space, with areas with heavy traffic volumes having the highest concentrations. Observations show qualitative agreement in terms of spatial patterns with a land-use regression (LUR) model for annual PM(2.5) concentrations.     

Chemical composition of PM2.5 and PM10 in Mexico City during winter 1997

PM2.5 and PM10 were measured over 24-h intervals at six core sites and at 25 satellite sites in and around Mexico City from 23 February to 22 March 1997. In addition, four 6-h samples were taken each day at three of the core sites. Sampling locations were selected to represent regional, central city, commercial, residential, and industrial portions of the city. Mass and light transmission concentrations were determined on all of the samples, while elements, ions and carbon were measured on approximately two-thirds of the samples. PM10 concentrations were highly variable, with almost three-fold differences between the highest and lowest concentrations. Fugitive dust was the major cause of PM10 differences, although carbon concentrations were also highly variable among the sampling sites. Approximately 50% of PM10 was in the PM2.5 fraction. The majority of PM mass was comprised of carbon, sulfate, nitrate, ammonium and crustal components, but in different proportions on different days and at different sites. The largest fine-particle components were carbonaceous aerosols, constituting approximately 50% of PM2.5 mass, followed by approximately 30% secondary inorganic aerosols and approximately 15% geological material. Geological material is the largest component of PM10, constituting approximately 50% of PM10 mass, followed by approximately 32% carbonaceous aerosols and approximately 17% secondary inorganic aerosols. Sulfate concentrations were twice as high as nitrate concentrations. Sulfate and nitrate were present as ammonium sulfate and ammonium nitrate. Approximately two-thirds of the ammonium sulfate measured in urban areas appears to have been transported from regions outside of the study domain, rather than formed from emissions in the urban area. Diurnal variations are apparent, with two-fold increases in concentration from night-time to daytime. Morning samples had the highest PM2.5 and PM10 mass, secondary inorganic aerosols and carbon concentrations, probably due to a shallow surface inversion and rush-hour traffic.     

The adverse effects of fine particle air pollution on respiratory function in the elderly

There is increasing concern that airborne particles are critical risk factors for adverse health conditions in susceptible populations. The objective of this panel study is to investigate an association between particulate matter and the peak expiratory flow rate (PEFR) in the elderly and to compare estimated risks using PM10 or PM2.5 levels as a measure of exposure. During a 2-year longitudinal follow-up study, we contacted subjects living in an asylum for the elderly, provided them with a mini-Wright peak flow meter, and instructed to record all the flow readings, any respiratory symptoms, passive smoking activity, and hours spent outdoors for that given day. Daily levels of particulate matter were measured by two separate mini-volume air samplers (for PM10 and PM2.5) placed on the rooftop of the two-story residence asylum building. In our statistical models, we assumed that the expected response varied linearly for each participant with a slope and intercept that depended on fixed or time-varying covariates using a mixed linear model. The daily mean levels of PM10 and PM2.5 were 78 microg/m3 and 56 microg/m3, respectively. For every 10 microg/m3 increase in PM10 and PM2.5 levels, there was an estimated PEFR change of -0.39 l/min (95% CI, -0.63, -0.14) and -0.54 l/min (95% CI, -0.89, -0.19), respectively. These data also suggest that fine particles have a more adverse respiratory health impact for sensitive individuals such as the elderly and that more research and control strategies should focus on the smaller particles associated with air pollution.     

Small-scale spatial variability of particle concentrations and traffic levels in Montreal: a pilot study

Little is known about the particulate exposure of populations living along major urban roads. The objective of this pilot study was to explore the small-scale spatial and temporal variability of the absorption coefficient of PM2.5 filters, as a surrogate for elemental carbon, in relation to levels of PM2.5, at residential sites with varying traffic densities in a large Canadian city. Concurrent 24-h measurements were performed at four residential sites during 7 weeks. A gradient existed across all four sites for the absorption coefficient of the filters (and NO2 levels). In contrast, the levels of PM2.5 were quite similar at all sites. The difference in the filter absorption coefficient of PM2.5 filters, between an urban background and a residential traffic site (with about 30000 vehicles/day), expressed as a percentage of the background site, was 40%. These results indicate that spatial variability in PM2.5 absorption coefficient can be observed with traffic intensity on a small scale within a North American city and suggests that regression modelling approaches similar to those used in European studies could be used to estimate exposure of the general population to traffic-related particles on a local scale in North America.     

Concentration and chemical characteristics of PM2.5 in Beijing, China: 2001-2002

Weekly PM2.5 samples were simultaneously collected at a semi-residential (Tsinghua University) and a downtown (Chegongzhuang) site in Beijing from August 2001 through September 2002. The ambient mass concentration and chemical composition of PM2.5 were determined. Analyses including elemental composition, water-soluble ions, and organic and elemental carbon were performed. The annual average concentrations of PM2.5 were 96.5 microg m(-3) and 106.9 microg m(-3) at CGZ and HU site, respectively. More than 80% of the PM2.5 mass concentrations were explained by carbonaceous species, secondary particles, crustal matters and trace elements at the two sites. Carbonaceous species were the most abundant components, constituting about 45% and 48% of the total PM2.5 mass concentrations at CGZ and THU site, respectively. SO4(2-), NO3- and NH4+ were three major ions, accounting for 37%, 23% and 20%, respectively, of the total mass of inorganic water-soluble ions.     

Influence of meteorological conditions and particulate matter on visual range impairment in Jinan, China

To understand the influence of aerosol particles and meteorological conditions on visual range in Jinan, the capital of Shandong Province, China, PM(2.5) and PM(10) samples were collected from November 2004 to September 2005. The mass concentrations of PM(2.5) and PM(10), concentrations of water-soluble ions in PM(2.5) and concentrations of black carbon (BC) in the atmosphere were analyzed. The decrease of visual range in Jinan results from the combined influence of PM(2.5), PM(10) and meteorological conditions. For the period studied, the average light extinction coefficient, b(ext), which was estimated from an equation developed by the IMPROVE network was 292 Mm(-1). Ammonium sulfate was the major contributor to visual range impairment, accounting for 41%, while ammonium nitrate, particulate organic matter (POM) and BC made comparable contributions accounting for 20%, 22% and 18%, respectively. This highlights the significance of secondary particles ((NH(4))(2)SO(4), NH(4)NO(3), POM) in visual range impairment in Jinan. The data from this study are also compared with the long-term variations of visual range in Jinan from 1961 to 2005.     

Approaching PM(2.5) and PM(2.5-10) source apportionment by mass balance analysis, principal component analysis and particle size distribution

A chemical characterization was carried out for PM(2.5) and PM(2.5-10) samples collected in a suburban area and the concentrations of 12 elements were determined in 8 size segregated fractions using a Berner Impactor. Two main objectives were proposed in this work: 1) to test for closure among chemical and gravimetric measurements of PM(2.5) and PM(2.5-10) and 2) evaluate the performance of Multilinear Regression Analysis (MLRA) and Mass Balance Analysis (MBA) in the determination of source contribution to Particulate Matter (PM) concentrations. The fraction unaccounted for by chemical analysis comprised on average 17% and 34% of gravimetric PM(2.5) and PM(2.5-10), respectively. The lack of closure in PM(2.5) and PM(2.5-10) mass (i.e., constituent concentrations not adding up to gravimetrically measured) could partly result from the presence of water associated with particles and errors in the estimation of unmeasured species. MLRA and MBA showed very similar results for the temporal variation of the source contributions. However, quantitatively important discrepancies could be observed, principally due to the lack of mass closure in PM(2.5) and PM(2.5-10). Both methods indicated that the major PM(2.5) aerosol mass contributors included secondary aerosol and vehicle exhaust. In the coarse fraction, marine and mineral aerosol contributions were predominant.     

Particle-associated polycyclic aromatic hydrocarbons in the atmospheric environment of Zonguldak, Turkey

Airborne fine (PM(2.5)) and coarse (PM(2.5-10)) particulate matter was collected from January to December in 2007 in Zonguldak, Turkey using dichotomous Partisol 2025 sampler. Fourteen selected polycyclic aromatic hydrocarbons (PAHs) in particulate matter were determined simultaneously by high-performance liquid chromatography with fluorescence detection (HPLC-FL) and seasonal distributions were examined. The source identification of PAHs in airborne particulates was performed by principal component analysis (PCA) in combination with diagnostic ratios. The predominant PAHs determined in PM(2.5) were pyrene, fluoranthene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene and benzo[a]pyrene. The total concentrations of PAHs were up to 464.0 ng m(-3) in fine and 28.0 ng m(-3) in coarse fraction in winter, whereas in summer times were up to 22.9 and 3.0 ng m(-3) respectively. Approximately 93.3% of total PAHs concentration was determined in PM(2.5) in winter and 84.0% in summer. The concentration levels of PAHs fluctuate significantly within a year with higher means and peak concentrations in the winter compared to that of summer times. Higher benzo(a)pyrene-equivalent (BaPE) concentrations of PAHs were obtained for PM(2.5) especially in winter. The results obtained from PCA in combination with diagnostic ratios revealed that coal combustion and vehicle emissions were the major pollutant sources for both PM(2.5) and PM(2.5-10) associated PAHs in studied area. Two principal components for PM(2.5) and three for PM(2.5-10) were identified and these accounted for 89.4 and 85.2% of the total variance respectively. The emissions from coal combustion were estimated to be the main source of PAHs in the ambient air particulates with contributions of 80.8% of total variance for PM(2.5) and 53.8% for PM(2.5-10).     

Trace elements total content and particle sizes distribution in the air particulate matter of a rural-residential area in north Italy investigated by instrumental neutron activation analysis

The concentrations (ng/m3) of more than 30 trace elements have been determined in the total air particulate of a rural-residential area in north Italy. By collecting the aerosols with multistage impactors the distribution of the trace elements in the different size-fractionated particles has been also investigated. The fine 'inhalable' fraction with particles of less than 10 microns in equivalent aerodynamic diameter (PM10) as well as the subsequent finest 'respirable' fractions with particles of 0-1.1 microns (alveolar), 1.1-4.6 microns (bronchial) and 4.6-9 microns (tracheo-pharynx) have been analyzed and evaluated. Apart from Pb, Cd and, in some cases, Ni and Cu which have been determined by ETAAS (electrothermal atomic absorption spectroscopy), all measurements have been carried out by instrumental neutron activation analysis (INAA).     

Elemental and organic carbon exposure in highway tollbooths: a study of Taiwanese toll station workers

The carbon composition of fine particles (PM(2.5)) from traffic exhausts may play a role in adverse health effects. The objective of this study was to assess the concentrations of elemental and organic carbon in PM(2.5) in traffic exhausts from different types of vehicles in the booths of Taiwanese toll station workers and estimate the relations between traffic density and carbon concentrations. Tollbooth indoor monitoring samples were collected for 10 days to assess the 8 h integrated PM(2.5) concentration. Particle samples were analyzed for the content of total carbon, and elemental, and organic carbon. The mean carbon concentrations in the bus and truck lanes were [total: 167.7 microg/m(3) (SD 79.8 microg/m(3)); elemental: 131.7 (66.2); organic: 36.0 (25.8)], substantially higher compared with the car lanes with cash payment [39.2 (29.5); 20.2 (19.5); 19.2 (14.6)] and the car lanes with ticket payment [34.1 (26.1); 15.8 (17.6); 18.5 (12.2)]. The increase in elemental carbon concentration per vehicle in the bus and truck lane was 14 and 9 times greater than that of car lanes of ticket payment and car lanes of cash payment. The mass fraction of carbonaceous species in PM(2.5) accounted for 54% in bus and truck lanes, whereas the corresponding figure was 30-31% for car lanes. Elemental carbon is an important component of diesel exhaust. Workers in toll stations are exposed to high levels of both elemental and organic carbon.     

Particulate matter and carbon monoxide multiple regression models using environmental characteristics in a high diesel-use area of Baguio City, Philippines

In Baguio City, Philippines, a mountainous city of 252,386 people where 61% of motor vehicles use diesel fuel, ambient particulate matter <2.5 microm (PM(2.5)) and <10 microm (PM(10)) in aerodynamic diameter and carbon monoxide (CO) were measured at 30 street-level locations for 15 min apiece during the early morning (4:50-6:30 am), morning rush hour (6:30-9:10 am) and afternoon rush hour (3:40-5:40 pm) in December 2004. Environmental observations (e.g. traffic-related variables, building/roadway designs, wind speed and direction, etc.) at each location were noted during each monitoring event. Multiple regression models were formulated to determine which pollution sources and environmental factors significantly affect ground-level PM(2.5), PM(10) and CO concentrations. The models showed statistically significant relationships between traffic and early morning particulate air pollution [(PM(2.5)p=0.021) and PM(10) (p=0.048)], traffic and morning rush hour CO (p=0.048), traffic and afternoon rush hour CO (p=0.034) and wind and early morning CO (p=0.044). The mean early morning, street-level PM(2.5) (110+/-8 microg/m3; mean+/-1 standard error) was not significantly different (p-value>0.05) from either rush hour PM(2.5) concentration (morning=98+/-7 microg/m3; afternoon=107+/-5 microg/m3) due to nocturnal inversions in spite of a 100% increase in automotive density during rush hours. Early morning street-level CO (3.0+/-1.7 ppm) differed from morning rush hour (4.1+/-2.3 ppm) (p=0.039) and afternoon rush hour (4.5+/-2.2 ppm) (p=0.007). Additionally, PM(2.5), PM(10), CO, nitrogen dioxide (NO2) and select volatile organic compounds were continuously measured at a downtown, third-story monitoring station along a busy roadway for 11 days. Twenty-four-hour average ambient concentrations were: PM(2.5)=72.9+/-21 microg/m3; CO=2.61+/-0.6 ppm; NO2=27.7+/-1.6 ppb; benzene=8.4+/-1.4 microg/m3; ethylbenzene=4.6+/-2.0 microg/m3; p-xylene=4.4+/-1.9 microg/m3; m-xylene=10.2+/-4.4 microg/m3; o-xylene=7.5+/-3.2 microg/m3. The multiple regression models suggest that traffic and wind in Baguio City, Philippines significantly affect street-level pollution concentrations. Ambient PM(2.5) levels measured are above USEPA daily (65 microg/m3) and Filipino/USEPA annual standards (15 microg/m3) with concentrations of a magnitude rarely seen in most countries except in areas where local topography plays a significant role in air pollution entrapment. The elevated pollution concentrations present and the diesel-rich nature of motor vehicle emissions are important pertaining to human exposure and health information and as such warrant public health concern.     

Bioreactivity of particulate matter in Beijing air: results from plasmid DNA assay

An in vitro plasmid assay was employed to study the bioreactivity of PM (particulate matter) in Beijing air. It was found that the TD20 (toxic dose of PM causing 20% of plasmid DNA damage) of Beijing PM can be as low as 28 microg ml(-1) and as high as >1000 microg ml(-1). Comparison of the physical properties, such as morphology and size distribution, and oxidative potential indicates that the PM(2.5) (particulate matter with an aerodynamic diameter of 2.5 microm or less) has a stronger oxidative capacity than PM(10) (particulate matter with an aerodynamic diameter of 10 microm or less), and that the higher number percentages of soot aggregates and lower number percentages of mineral and fly ashes are associated with the higher oxidative capacity. Although the mass of PM(10) during dust storms is commonly 5 times higher than that during non-dust storm episodes, the oxidative capacity of PM(10)s of dust storms is much lower than that of the non-dust storm PM(10)s. The water-soluble fractions and intact whole particle solutions of Beijing airborne particles produce similar plasmid assay results, demonstrating that the bioreactivity of Beijing airborne particles is mainly sourced from the water-soluble fraction. In the samples with stronger bioreactivity, the total analyzed water soluble Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As and Pb (ppm) concentrations are higher. The water soluble zinc shows a good negative correlation with TD20s, suggesting that the water-soluble zinc is probably the major element responsible for the plasmid DNA damage.