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1.
This research evaluates commuter exposure to particulate matter during pre-journey commute segments for passengers waiting at bus stops by investigating 840 min of simultaneous exposure levels, both inside and outside seven bus shelters in Buffalo, New York. A multivariate regression model is used to estimate the relation between exposure to particulate matter (PM 2.5 measured in μg m ?3) and three vectors of determinants: time and location, physical setting and placement, and environmental factors. Four determinants have a statistically significant effect on particulate matter: time of day, passengers’ waiting location, land use near the bus shelter, and the presence of cigarette smoking at the bus shelter. Model results suggest that exposure to PM 2.5 inside a bus shelter is 2.63 μg m ?3 (or 18 percent) higher than exposure outside a bus shelter, perhaps due in part to the presence of cigarette smoking. Morning exposure levels are 6.51 μg m ?3 (or 52 percent) higher than afternoon levels. Placement of bus stops can affect exposure to particulate matter for those waiting inside and outside of shelters: air samples at bus shelters located in building canyons have higher particulate matter than bus shelters located near open space. 相似文献
2.
This paper presents results from an in-vehicle air quality study of public transit buses in Toledo, Ohio, involving continuous monitoring, and experimental and statistical analyses to understand in-vehicle particulate matter (PM) behavior inside buses operating on B20-grade biodiesel fuel. The study also focused on evaluating the effects of vehicle’s fuel type, operating periods, operation status, passenger counts, traffic conditions, and the seasonal and meteorological variation on particulates with aerodynamic diameter less than 1 micron (PM 1.0). The study found that the average PM 1.0 mass concentrations in B20-grade biodiesel-fueled bus compartments were approximately 15 μg m ?3, while PM 2.5 and PM 10 concentration averages were approximately 19 μg m ?3 and 37 μg m ?3, respectively. It was also observed that average hourly concentration trends of PM 1.0 and PM 2.5 followed a “μ-shaped” pattern during transit hours.Experimental analyses revealed that the in-vehicle PM 1.0 mass concentrations were higher inside diesel-fueled buses (10.0–71.0 μg m ?3 with a mean of 31.8 μg m ?3) as compared to biodiesel buses (3.3–33.5 μg m ?3 with a mean of 15.3 μg m ?3) when the windows were kept open. Vehicle idling conditions and open door status were found to facilitate smaller particle concentrations inside the cabin, while closed door facilitated larger particle concentrations suggesting that smaller particles were originating outside the vehicle and larger particles were formed within the cabin, potentially from passenger activity. The study also found that PM 1.0 mass concentrations at the back of bus compartment (5.7–39.1 μg m ?3 with a mean of 28.3 μg m ?3) were higher than the concentrations in the front (5.7–25.9 μg m ?3 with a mean of 21.9 μg m ?3), and the mass concentrations inside the bus compartment were generally 30–70% lower than the just-outside concentrations. Further, bus route, window position, and time of day were found to affect the in-vehicle PM concentrations significantly. Overall, the in-vehicle PM 1.0 concentrations inside the buses operating on B20-grade biodiesel ranged from 0.7 μg m ?3 to 243 μg m ?3, with a median of 11.6 μg m ?3.Statistical models developed to study the effects of vehicle operation and ambient conditions on in-vehicle PM concentrations suggested that while open door status was the most important influencing variable for finer particles and higher passenger activity resulted in higher coarse particles concentrations inside the vehicle compartments, ambient PM concentrations contributed to all PM fractions inside the bus irrespective of particle size. 相似文献
3.
PM 10 measurements were started in November 1992 at Melpitz site. The mean PM 10 concentration in 1993 was 38 μg m ?3 in the summer season (May until October) and about 44 μg m ?3 in the winter season (November until April). The mean PM 10 level decreased until 1999 and varies now in ranges from 20–34 μg m ?3 to 17–24 μg m ?3 (minimum and maximum mean values for 1999–2008) in winter and summer seasons, respectively. High volume filter samples of particles PM 10, PM 2.5 and PM 1 were characterized for mass, water-soluble ions, organic and elemental carbon from 2004 until 2008. The percentage of PM 2.5 in PM 10 varies between summer (71.6%) and winter seasons (81.9%). Mean concentrations of PM 10, PM 2.5 and PM 1 in Melpitz were 20, 15, and 13 μg m ?3 in 2004, 22, 18, and 13 μg m ?3 in 2005, 24, 19, and 12 μg m ?3 in 2006 and 22, 17, and 12 μg m ?3 in 2007, respectively. In the four winters the rural background concentration PM 10 at Melpitz exceeded the daily 50 μg m ?3 limit for Europe on 8, 8, 7 and 6 days, respectively.Findings for a simple two-sector-classification of the samples (May 2004 until April 2008) using 96-h backward trajectories for the identification of source regions are: Air masses were transported most of time (60%) from the western sector and secondly (17%) from the eastern sector. The lowest daily mean mass concentration PM 10 were found during western inflow in summer (17 μg m ?3) containing low amounts of sulphate (2.4 μg m ?3), nitrate (1.7 μg m ?3), ammonium (1.1 μg m ?3) and TC (3.7 μg m ?3). In opposite the highest mean mass concentration PM 10 was found during eastern inflow in winter (35 μg m ?3) with high amounts of sulphate (6.1 μg m ?3), nitrate (5.4 μg m ?3), ammonium (3.8 μg m ?3) and TC (9.4 μg m ?3). An estimation of secondary formed OC (SOA) shows 0.8–0.9 μg m ?3 for air masses from West and 2.1–2.2 μg m ?3 from East. The seasonal difference can be neglected.The half-hourly measurements of the particle mass concentration PM 10 evaluated as mean daily courses using a TEOM ® show low values (14–21 μg m ?3) in summer and winter for air masses transported from West and the highest concentrations (31–38 μg m ?3) in winter for air masses from East.The results demonstrate the influence of meteorological parameters on long-range transport, secondary particle mass formation and re-emission which modify mass concentration and composition of PM 10, PM 2.5 and PM 1. Melpitz site is located in the East of Germany faraway from strong local anthropogenic emissions (rural background). Therefore, this site is suitable for investigation of the influence of long-range transport of air pollution in continental air masses from the East with source regions inside and outside of the European Union. 相似文献
4.
We report on ambient atmospheric aerosols present at sea during the Atlantic–Mediterranean voyage of Oceanic II (The Scholar Ship) in spring 2008. A record was obtained of hourly PM 10, PM 2.5, and PM 1 particle size fraction concentrations and 24-h filter samples for chemical analysis which allowed for comparison between levels of crustal particles, sea spray, total carbon, and secondary inorganic aerosols. On-board monitoring was continuous from the equatorial Atlantic to the Straits of Gibraltar, across the Mediterranean to Istanbul, and back via Lisbon to the English Channel. Initially clean air in the open Atlantic registered PM 10 levels <10 μg m ?3 but became progressively polluted by increasingly coarse PM as the ship approached land. Away from major port cities, the main sources of atmospheric contamination identified were dust intrusions from North Africa (NAF), smoke plumes from biomass burning in sub-Saharan Africa and Russia, industrial sulphate clouds and other regional pollution sources transported from Europe, sea spray during rough seas, and plumes emanating from islands. Under dry NAF intrusions PM 10 daily mean levels averaged 40–60 μg m ?3 (30–40 μg m ?3 PM 2.5; c. 20 μg m ?3 PM 1), peaking briefly to >120 μg m ?3 (hourly mean) when the ship passed through curtains of higher dust concentrations amassed at the frontal edge of the dust cloud. PM 1/PM 10 ratios ranged from very low during desert dust intrusions (0.3–0.4) to very high during anthropogenic pollution plume events (0.8–1). 相似文献
5.
As indoor smoking bans have become widely adopted, some U.S. communities are considering restricting smoking outdoors, creating a need for measurements of air pollution near smokers outdoors. Personal exposure experiments were conducted with four to five participants at six sidewalk bus stops located 1.5–3.3 m from the curb of two heavily traveled California arterial highways with 3300–5100 vehicles per hour. At each bus stop, a smoker in the group smoked a cigarette. Gravimetrically calibrated continuous monitors were used to measure fine particle concentrations (aerodynamic diameter ≤2.5 µm; PM 2.5) in the breathing zones (within 0.2 m from the nose and mouth) of each participant. At each bus stop, ultrafine particles (UFP), wind speed, temperature, relative humidity, and traffic counts were also measured. For 13 cigarette experiments, the mean PM 2.5 personal exposure of the nonsmoker seated 0.5 m from the smoker during a 5-min cigarette ranged from 15 to 153 µg/m 3. Of four persons seated on the bench, the smoker received the highest PM 2.5 breathing-zone exposure of 192 µg/m 3. There was a strong proximity effect: nonsmokers at distances 0.5, 1.0, and 1.5 m from the smoker received mean PM 2.5 personal exposures of 59, 40, and 28 µg/m 3, respectively, compared with a background level of 1.7 µg/m 3. Like the PM 2.5 concentrations, UFP concentrations measured 0.5 m from the smoker increased abruptly when a cigarette started and decreased when the cigarette ended, averaging 44,500 particles/cm 3 compared with the background level of 7200 particles/cm 3. During nonsmoking periods, the UFP background concentrations showed occasional peaks due to traffic, whereas PM 2.5 background concentrations were extremely low. The results indicate that a single cigarette smoked outdoors at a bus stop can cause PM 2.5 and UFP concentrations near the smoker that are 16–35 and 6.2 times, respectively, higher than the background concentrations due to cars and trucks on an adjacent arterial highway. Implications: Rules banning smoking indoors have been widely adopted in the United States and in many countries. Some communities are considering smoking bans that would apply to outdoor locations. Although many measurements are available of pollutant concentrations from secondhand smoke at indoor locations, few measurements are available of exposure to secondhand smoke outdoors. This study provides new data on exposure to fine and ultrafine particles from secondhand smoke near a smoker outdoors. The levels are compared with the exposure measured next to a highway. The findings are important for policies that might be developed for reducing exposure to secondhand smoke outdoors. 相似文献
6.
Thoracic (PM 10), fine thoracic (PM 2.5) and sub-micrometer (PM 1) airborne particulate matter was sampled during day and night. In total, about 100 indoor and outdoor samples were collected for each fraction at ten different office environments. Energy-dispersive X-ray fluorescence spectrometry and ion chromatography were applied for the quantification of some major and minor elements and ions in the collected aerosols. During daytime, mass concentrations were in the ranges: 11–29, 8.1–24, and 6.6–18 μg m ?3, with averages of 20 ± 1, 15.0 ± 0.9, and 11.0 ± 0.8 μg m ?3, respectively. At night, mass concentrations were found to be significantly lower for all fractions. Indoor PM 1 concentrations exceeded the corresponding outdoor levels during office hours and were thought to be elevated by office printers. Particles with diameters between 1 and 2.5 μm and 2.5 and 10 μm were mainly associated with soil dust elements and were clearly subjected to distinct periods of settling/resuspension. Indoor NO 3? levels were found to follow specific microclimatic conditions at the office environments, while daytime levels of sub-micrometer Cl ? were possibly elevated by the use of Cl-containing cleaning products. Indoor carbon black concentrations were sometimes as high as 22 μg m ?3 and were strongly correlated with outdoor traffic conditions. 相似文献
7.
In developed nations people spend about 90% of their time indoors. The relationship between indoor and outdoor air pollution levels is important for the understanding of the health effects of outdoor air pollution. Although other studies describe both the outdoor and indoor atmospheric environment, few excluded a priori major indoor sources, measured the air exchange rate, included more than one micro-environment and included the presence of human activity. PM 2.5, soot, NO 2 and the air exchange rate were measured during winter and summer indoors and outdoors at 18 homes (mostly apartments) of 18 children (6–11-years-old) and also at the six schools and 10 pre-schools that the children attended. The three types of indoor environments were free of environmental tobacco smoke and gas appliances, as the aim was to asses to what extent PM 2.5, soot and NO 2 infiltrate from outdoors to indoors. The median indoor and outdoor PM 2.5 levels were 8.4 μg m ?3 and 9.3 μg m ?3, respectively. The median indoor levels for soot and NO 2 were 0.66 m ?1 × 10 ?5 and 10.0 μg m ?3, respectively. The respective outdoor levels were 0.96 m ?1 × 10 ?5 and 12.4 μg m ?3. The median indoor/outdoor (I/O) ratios were 0.93, 0.76 and 0.92 for PM 2.5, soot and NO 2, respectively. Their infiltration factors were influenced by the micro-environment, ventilation type and air exchange rate, with aggregated values of 0.25, 0.55 and 0.64, respectively. Indoor and outdoor NO 2 levels were strongly associated ( R2 = 0.71), followed by soot ( R2 = 0.50) and PM 2.5 ( R2 = 0.16). In Stockholm, the three major indoor environments occupied by children offer little protection against combustion-related particles and gases in the outdoor air. Outdoor PM 2.5 seems to infiltrate less, but indoor sources compensate. 相似文献
8.
Personal exposure to particulate matter of aerodynamic diameter under 2.5 μm (PM 2.5) was monitored using a DustTrak nephelometer. The battery-operated unit, worn by an adult individual for a period of approximately one year, logged integrated average PM 2.5 concentrations over 5 min intervals. A detailed time-activity diary was used to record the experimental subject’s movement and the microenvironments visited. Altogether 239 days covering all the months (except April) were available for the analysis. In total, 60 463 acceptable 5-min averages were obtained. The dataset was divided into 7 indoor and 4 outdoor microenvironments. Of the total time, 84% was spent indoors, 10.9% outdoors and 5.1% in transport. The indoor 5-min PM 2.5 average was higher (55.7 μg m ?3) than the outdoor value (49.8 μg m ?3). The highest 5-min PM 2.5 average concentration was detected in restaurant microenvironments (1103 μg m ?3), the second highest 5-min average concentration was recorded in indoor spaces heated by stoves burning solid fuels (420 μg m ?3). The lowest 5-min mean aerosol concentrations were detected outdoors in rural/natural environments (25 μg m ?3) and indoors at the monitored person’s home (36 μg m ?3). Outdoor and indoor concentrations of PM 2.5 measured by the nephelometer at home and during movement in the vicinity of the experimental subject’s home were compared with those of the nearest fixed-site monitor of the national air quality monitoring network. The high correlation coefficient (0.78) between the personal and fixed-site monitor aerosol concentrations suggested that fixed-site monitor data can be used as proxies for personal exposure in residential and some other microenvironments. Collocated measurements with a reference method (β-attenuation) showed a non-linear systematic bias of the light-scattering method, limiting the use of direct concentration readings for exact exposure analysis. 相似文献
9.
Particulate pollution has been clearly linked with adverse health impacts from open fire cookstoves, and indoor air concentrations are frequently used as a proxy for exposures in health studies. Implicit are the assumptions that the size distributions for the open fire and improved stove are not significantly different, and that the relationship between indoor concentrations and personal exposures is the same between stoves. To evaluate the impact of these assumptions size distributions of particulate matter in indoor air were measured with the Sioutas cascade impactor in homes using open fires and improved Patsari stoves in a rural Purepecha community in Michoacan, Mexico. On average indoor concentrations of particles less than 0.25 μm were 72% reduced in homes with improved Patsari stoves, reflecting a reduced contribution of this size fraction to PM 2.5 mass concentrations from 68% to 48%. As a result the mass median diameter of indoor PM 2.5 particulate matter was increased by 29% with the Patsari improved stove compared to the open fire (from 0.42 μm to 0.59 μm, respectively). Personal PM 2.5 exposure concentrations for women in homes using open fires were approximately 61% of indoor concentration levels (156 μg m ?3 and 257 μg m ?3 respectively). In contrast personal exposure concentrations were 77% times indoor air concentration levels for women in homes using improved Patsari stoves (78 μg m ?3and 101 μg m ?3 respectively). Thus, if indoor air concentrations are used in health and epidemiologic studies significant bias may result if the shift in size distribution and the change in relationship between indoor air concentrations and personal exposure concentrations are not accounted for between different stove types. 相似文献
10.
Atmospheric PM pollution from traffic comprises not only direct emissions but also non-exhaust emissions because resuspension of road dust that can produce high human exposure to heavy metals, metalloids, and mineral matter. A key task for establishing mitigation or preventive measures is estimating the contribution of road dust resuspension to the atmospheric PM mixture. Several source apportionment studies, applying receptor modeling at urban background sites, have shown the difficulty in identifying a road dust source separately from other mineral sources or vehicular exhausts. The Multilinear Engine (ME-2) is a computer program that can solve the Positive Matrix Factorization (PMF) problem. ME-2 uses a programming language permitting the solution to be guided toward some possible targets that can be derived from a priori knowledge of sources (chemical profile, ratios, etc.). This feature makes it especially suitable for source apportionment studies where partial knowledge of the sources is available.In the present study ME-2 was applied to data from an urban background site of Barcelona (Spain) to quantify the contribution of road dust resuspension to PM 10 and PM 2.5 concentrations. Given that recently the emission profile of local resuspended road dust was obtained (Amato, F., Pandolfi, M., Viana, M., Querol, X., Alastuey, A., Moreno, T., 2009. Spatial and chemical patterns of PM 10 in road dust deposited in urban environment. Atmospheric Environment 43 (9), 1650–1659), such a priori information was introduced in the model as auxiliary terms of the object function to be minimized by the implementation of the so-called “pulling equations”.ME-2 permitted to enhance the basic PMF solution (obtained by PMF2) identifying, beside the seven sources of PMF2, the road dust source which accounted for 6.9 μg m ?3 (17%) in PM 10, 2.2 μg m ?3 (8%) of PM 2.5 and 0.3 μg m ?3 (2%) of PM 1. This reveals that resuspension was responsible of the 37%, 15% and 3% of total traffic emissions respectively in PM 10, PM 2.5 and PM 1. Therefore the overall traffic contribution resulted in 18 μg m ?3 (46%) in PM 10, 14 μg m ?3 (51%) in PM 2.5 and 8 μg m ?3 (48%) in PM 1. In PMF2 this mass explained by road dust resuspension was redistributed among the rest of sources, increasing mostly the mineral, secondary nitrate and aged sea salt contributions. 相似文献
11.
This study investigates the levels of particulate matter smaller than 2.5 μm (PM 2.5) and some selected volatile organic compounds (VOCs) at 12 photocopy centers in Taiwan from November 2004 to June 2005. The results of BTEXS (benzene, toluene, ethylbenzene, xylenes and styrene) measurements indicated that toluene had the highest concentration in all photocopy centers, while the concentration of the other four compounds varied among the 12 photocopy centers. The average background-corrected eight-hour PM 2.5 in the 12 photocopy centers ranged from 10 to 83 μg m −3 with an average of 40 μg m −3. The 24-h indoor PM 2.5 at the photocopy centers was estimated and at two photocopy centers exceeded 100 μg m −3, the 24-h indoor PM 2.5 guideline recommended by the Taiwan EPA. The ozone level and particle size distribution at another photocopy center were monitored and indicated that the ozone level increased when the photocopying started and the average ozone level at some photocopy centers during business hour may exceed the value (50 ppb) recommended by the Taiwan EPA. The particle size distribution monitored during photocopying indicated that the emitted particles were much smaller than the original toner powders. Additionally, the number concentration of particles that were smaller than 0.5 μm was found to increase during the first hour of photocopying and it increased as the particle size decreased. The ultrafine particle (UFP, <100 nm) dominated the number concentration and the peak concentration appeared at sizes of under 50 nm. A high number concentration of UFP was found with a peak value of 1E+8 particles cm −3 during photocopying. The decline of UFP concentration was observed after the first hour and the decline is likely attributable to the surface deposition of charged particles, which are charged primarily by the diffusion charging of corona devices in the photocopier. This study concludes that ozone and UFP concentrations in photocopy centers should be concerned in view of indoor air quality and human health. The corona devices in photocopiers and photocopier-emitted VOCs have the potential to initiate indoor air chemistry during photocopying and result in the formation of UFP. 相似文献
12.
Carbon monoxide (CO) and particulate matter (PM 2.5) were measured in two reconstructed Danish farmhouses (17–19th century) during two weeks of summer. During the first week intensive measurements were performed while test cooking fires were burned, during the second week the houses were monitored while occupied by guest families. A masonry hearth was located in the middle of each house for open cooking fires and with heating stoves. One house had a chimney leading to the outside over the hearth; in the other, a brickwork hood led the smoke into an attic and through holes in the roof. During the first week the concentration of PM 2.5 averaged daily between 138 and 1650 μg m ?3 inside the hearths and 21–160 μg m ?3 in adjacent living rooms. CO averaged daily between 0.21 and 1.9 ppm in living areas, and up to 12 ppm in the hearths. Highest concentrations were measured when two fires were lit at the same time, which would cause high personal exposure for someone working in the kitchens. 15 min averages of up to 25 400 μg m ?3 (PM 2.5) and 260 ppm CO were recorded. WHO air quality guidelines were occasionally exceeded for CO and constantly for PM 2.5. However, air exchange and air distribution measurements revealed a large draw in the chimney, which ensured a fast removal of wood smoke from the hearth area. The guest families were in average exposed to no more than 0.21 ppm CO during 48 h. Based on a hypothetical time-activity pattern, however, a woman living in this type of house during the 17–19th century would be exposed to daily averages of 1.1 ppm CO and 196 μg m ?3 PM 2.5, which exceeds WHO guideline for PM 2.5, and is comparable to what is today observed for women in rural areas of developing countries. 相似文献
13.
An apartment bedroom located in a residential area of Aveiro (Portugal) was selected with the aim of characterizing the cellulose content of indoor aerosol particles. Two sets of samples were taken: (1) PM 10 collected simultaneously in indoor and outdoor air; (2) PM 10 and PM 2.5 collected simultaneously in indoor air. The aerosol particles were concentrated on quartz fibre filters with low-volume samplers equipped with size selective inlets. The filters were weighed and then extracted for cellulose analysis by an enzymatic method. The average indoor cellulose concentration was 1.01 ± 0.24 μg m ?3, whereas the average outdoor cellulose concentration was 0.078 ± 0.047 μg m ?3, accounting for 4.0% and 0.4%, respectively, of the PM 10 mass. The corresponding average ratio between indoor and outdoor cellulose concentrations was 11.1 ± 4.9, indicating that cellulose particles were generated indoors, most likely due to the handling of cotton-made textiles as a result of routine daily activities in the bedroom. Indoor cellulose concentrations averaged 1.22 ± 0.53 μg m ?3 in the aerosol coarse fraction (determined from the difference between PM 10 and PM 2.5 concentrations) and averaged 0.38 ± 0.13 μg m ?3 in the aerosol fine fraction. The average ratio between the coarse and fine fractions of cellulose concentrations in the indoor air was 3.6 ± 2.1. This ratio is in line with the primary origin of this biopolymer. Results from this study provide the first experimental evidence in support of a significant contribution of cellulose to the mass of suspended particles in indoor air. 相似文献
14.
Particulate matter, including coarse particles (PM 2.5–10, aerodynamic diameter of particle between 2.5 and 10 μm) and fine particles (PM 2.5, aerodynamic diameter of particle lower than 2.5 μm) and their compositions, including elemental carbon, organic carbon, and 11 water-soluble ionic species, and elements, were measured in a tunnel study. A comparison of the six-hour average of light-duty vehicle (LDV) flow of the two sampling periods showed that the peak hours over the weekend were higher than those on weekdays. However, the flow of heavy-duty vehicles (HDVs) on the weekdays was significant higher than that during the weekend in this study. EC and OC content were 49% for PM 2.5–10 and 47% for PM 2.5 in the tunnel center. EC content was higher than OC content in PM 2.5–10, but EC was about 2.3 times OC for PM 2.5. Sulfate, nitrate, ammonium were the main species for PM 2.5–10 and PM 2.5. The element contents of Na, Al, Ca, Fe and K were over 0.8 μg m ?3 in PM 2.5–10 and PM 2.5. In addition, the concentrations of S, Ba, Pb, and Zn were higher than 0.1 μg m ?3 for PM 2.5–10 and PM 2.5. The emission factors of PM 2.5–10 and PM 2.5 were 18 ± 6.5 and 39 ± 11 mg km ?1-vehicle, respectively. The emission factors of EC/OC were 3.6/2.7 mg km ?1-vehicle for PM 2.5–10 and 15/4.7 mg km ?1-vehicle for PM 2.5 Furthermore, the emission factors of water-soluble ions were 0.028(Mg 2+)–0.81(SO 42?) and 0.027(NO 2?)–0.97(SO 42?) mg km ?1-vehicle for PM 2.5–10 and PM 2.5, respectively. Elemental emission factors were 0.003(V)–1.6(Fe) and 0.001(Cd)–1.05(Na) mg km ?1-vehicle for PM 2.5–10 and PM 2.5, respectively. 相似文献
15.
Concentrations of ultrafine (<0.1 μm) particles (UFPs) and PM 2.5 (<2.5 μm) were measured whilst commuting along a similar route by train, bus, ferry and automobile in Sydney, Australia. One trip on each transport mode was undertaken during both morning and evening peak hours throughout a working week, for a total of 40 trips. Analyses comprised one-way ANOVA to compare overall (i.e. all trips combined) geometric mean concentrations of both particle fractions measured across transport modes, and assessment of both the correlation between wind speed and individual trip means of UFPs and PM 2.5, and the correlation between the two particle fractions. Overall geometric mean concentrations of UFPs and PM 2.5 ranged from 2.8 (train) to 8.4 (bus) × 10 4 particles cm ?3 and 22.6 (automobile) to 29.6 (bus) μg m ?3, respectively, and a statistically significant difference ( p < 0.001) between modes was found for both particle fractions. Individual trip geometric mean concentrations were between 9.7 × 10 3 (train) and 2.2 × 10 5 (bus) particles cm ?3 and 9.5 (train) to 78.7 (train) μg m ?3. Estimated commuter exposures were variable, and the highest return trip mean PM 2.5 exposure occurred in the ferry mode, whilst the highest UFP exposure occurred during bus trips. The correlation between fractions was generally poor, and in keeping with the duality of particle mass and number emissions in vehicle-dominated urban areas. Wind speed was negatively correlated with, and a generally poor determinant of, UFP and PM 2.5 concentrations, suggesting a more significant role for other factors in determining commuter exposure. 相似文献
16.
Indoor and outdoor particulate matter (PM 0.3-10) number concentrations were established in two medieval churches in Cyprus. In both churches incense was burnt occasionally during Mass. The highest indoor PM 0.5-1 concentrations compared with outdoors (10.7 times higher) were observed in the church that burning of candles indoors was allowed. Peak indoor black carbon concentration was 6.8 μg m −3 in the instances that incense was burning and 13.4 μg m −3 in the instances that the candles were burning (outdoor levels ranged between 0.6 and 1.3 μg m −3). From the water soluble inorganic components determined in PM 10, calcium prevailed in all samples indoors or outdoors, whilst high potassium concentration indoors were a clear marker of combustion. Indoor sources of PM were clearly identified and their emission strengths were estimated via modeling of the results. Indoor estimated PM 0.3-10 mass concentrations exceeded air quality standards for human health protection and for the preservation of works of art. 相似文献
17.
Long-term study of air pollution plays a decisive role in formulating and refining pollution control strategies. In this study, two 12-month measurements of PM 2.5 mass and speciation were conducted in 00/01 and 04/05 to determine long-term trend and spatial variations of PM 2.5 mass and chemical composition in Hong Kong. This study covered three sites with different land-use characteristics, namely roadside, urban, and rural environments. The highest annual average PM 2.5 concentration was observed at the roadside site (58.0±2.0 μg m −3 (average±2 σ) in 00/01 and 53.0±2.7 μg m −3 in 04/05), followed by the urban site (33.9±2.5 μg m −3 in 00/01 and 39.0±2.0 μg m −3 in 04/05), and the rural site (23.7±1.9 μg m −3 in 00/01 and 28.4±2.4 μg m −3 in 04/05). The lowest PM 2.5 level measured at the rural site was still higher than the United States’ annual average National Ambient Air Quality Standard of 15 μg m −3. As expected, seasonal variations of PM 2.5 mass concentration at the three sites were similar: higher in autumn/winter and lower in summer. Comparing PM 2.5 data in 04/05 with those collected in 00/01, a reduction in PM 2.5 mass concentration at the roadside (8.7%) but an increase at the urban (15%) and rural (20%) sites were observed. The reduction of PM 2.5 at the roadside was attributed to the decrease of carbonaceous aerosols (organic carbon and elemental carbon) (>30%), indicating the effective control of motor vehicle emissions over the period. On the other hand, the sulfate concentration at the three sites was consistent regardless of different land-use characteristics in both studies. The lack of spatial variation of sulfate concentrations in PM 2.5 implied its origin of regional contribution. Moreover, over 36% growth in sulfate concentration was found from 00/01 to 04/05, suggesting a significant increase in regional sulfate pollution over the years. More quantitative techniques such as receptor models and chemical transport models are required to assess the temporal variations of source contributions to ambient PM 2.5 mass and chemical speciation in Hong Kong. 相似文献
18.
This study conducted roadside particulate sampling to measure the total suspended particulate (TSP), PM 10 (particles <10 μm in aerodynamic diameter) and PM 2.5 (particles <2.5 μm in aerodynamic diameter) mass concentration in 11 urbanized and densely populated districts in Hong Kong. One hundred and thirty-three samples were obtained to measure the mass concentrations of TSP, PM 10 and PM 2.5. According to these results, the TSP, PM 10 and PM 2.5 mass concentrations varied from 94.85 to 301.63 μg m −3, 67.67 to 142.68 μg m −3 and 50.01 to 125.12 μg m −3, respectively. The PM 2.5/PM 10 ratio of all samples was 0.82 which ranged from 0.62 to 0.95. The PM levels and PM ratios in metropolitan Hong Kong significantly fluctuated from site-to-site and over time. The PM 2.5 mass concentration in different districts corresponding to urban industrial, new town, urban residential and urban commercial were 77.64, 87.50, 106.96 and 88.54 μg m −3, respectively. The PM 2.5 level is high in Hong Kong, and for individual sampling, more than 60% daily measurements exceeded the NAAQS. The mass fraction of PM 2.5 in PM 10 and TSP is relatively high when compared with overseas studies. 相似文献
19.
Between November 1995 and October 1996, particulate matter concentrations (PM 10 and PM 2.5) were measured in 25 study areas in six Central and Eastern European countries: Bulgaria, Czech Republic, Hungary, Poland, Romania and Slovak Republic. To assess annual mean concentration levels, 24-h averaged concentrations were measured every sixth day on a fixed urban background site using Harvard impactors with a 2.5 and 10 μm cut-point. The concentration of the coarse fraction of PM 10 (PM 10−2.5) was calculated as the difference between the PM 10 and the PM 2.5 concentration. Spatial variation within study areas was assessed by additional sampling on one or two urban background sites within each study area for two periods of 1 month. QA/QC procedures were implemented to ensure comparability of results between study areas. A two to threefold concentration range was found between study areas, ranging from an annual mean of 41 to 98 μg m −3 for PM 10, from 29 to 68 μg m −3 for PM 2.5 and from 12 to 40 μg m −3 for PM 10−2.5. The lowest concentrations were found in the Slovak Republic, the highest concentrations in Bulgaria and Poland. The variation in PM 10 and PM 2.5 concentrations between study areas was about 4 times greater than the spatial variation within study areas suggesting that measurements at a single sampling site sufficiently characterise the exposure of the population in the study areas. PM 10 concentrations increased considerably during the heating season, ranging from an average increase of 18 μg m −3 in the Slovak Republic to 45 μg m −3 in Poland. The increase of PM 10 was mainly driven by increases in PM 2.5; PM 10−2.5 concentrations changed only marginally or even decreased. Overall, the results indicate high levels of particulate air pollution in Central and Eastern Europe with large changes between seasons, likely caused by local heating. 相似文献
20.
The extent of the exceedance of the EU limit values for nitrogen dioxide (NO 2) and particulate matter (PM 10) concentrations within the Netherlands is expected to decrease significantly, in the coming years. Whether limit values will actually be exceeded, in the next decade, depends not only on European, national and local policies, but also on the effects of inevitable interannual meteorological fluctuations. An analysis of model calculations and measurements yields variations (1 sigma) in the annual average concentration of about 5% for NO 2 and 9% for PM 10, due to meteorological fluctuations. These deviations from long-term average concentrations affect assessments of future levels, set against limit values. For instance, an NO 2 concentration of 39 μg m ?3, estimated for a given year with long-term average meteorology, indicates that it is likely (chance >66%) that the limit value of 40 μg m ?3 will not be exceeded in that particular year. At the same time, the estimation also indicates, for example, that this situation is unlikely (change <33%) to continue for three years in a row. However, with an estimated concentration of 38 μg m ?3, it is likely that the limit value will not be exceeded for three years in a row. The limit value for the daily average PM 10 concentration is equivalent to an annual average of about 32 μg m ?3. This threshold is unlikely to be exceeded for three years in a row, when an annual average concentration of 29 μg m ?3 is estimated. Interannual variations in concentrations of NO 2 and PM 10 are linked to large-scale meteorological fluctuations. Therefore, similar results can be expected for other European countries. 相似文献
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