Particulate oxidative burden associated with firework activity

Firework events are capable of inducing particulate matter (PM) episodes that lead to exceedances of regulatory limit values. As short-term peaks in ambient PM concentration have been associated with negative impacts on respiratory and cardiovascular health, we performed a detailed study of the consequences of firework events in London on ambient air quality and PM composition. These changes were further related to the oxidative activity of daily PM samples by assessing their capacity to drive the oxidation of physiologically important lung antioxidants including ascorbate, glutathione and urate (oxidative potential, OP). Twenty-four hour ambient PM samples were collected at the Marylebone Road sampling site in Central London over a three week period, including two major festivals celebrated with pyrotechnic events: Guy Fawkes Night and Diwali. Pyrotechnic combustion events were characterized by increased gas phase pollutants levels (NO(x) and SO(2)), elevated PM mass concentrations, and trace metal concentrations (specifically Sr, Mg, K, Ba, and Pb). Relationships between NO(x), benzene, and PM(10) were used to apportion firework and traffic source fractions. A positive significant relationship was found between PM oxidative burden and individual trace metals associated with each of these apportioned source fractions. The level of exposure to each source fraction was significantly associated with the total OP. The firework contribution to PM total OP, on a unit mass basis, was greater than that associated with traffic sources: a 1 μg elevation in firework and traffic PM fraction concentration was associated with a 6.5 ± 1.5 OP(T) μg(-1) and 5.2 ± 1.4 OP(T) μg(-1) increase, respectively. In the case of glutathione depletion, firework particulate OP (3.5 ± 0.8 OP(GSH) μg(-1)) considerably exceeded that due to traffic particles (2.2 ± 0.8 OP(GSH) μg(-1)). Therefore, in light of the elevated PM concentrations caused by firework activity and the increased oxidative activity of this PM source, there is value in examining if firework derived PM is related to acute respiratory outcomes.     

Spatiotemporal aspects of real-time PM(2.5): low- and middle-income neighborhoods in Bangalore, India

We measured outdoor fine particulate matter (PM(2.5)) concentrations in a low- and a nearby middle-income neighborhood in Bangalore, India. Each neighborhood included sampling locations near and not near a major road. One-minute average concentrations were recorded for 168 days during September 2008 to May 2009 using a gravimetric-corrected nephelometer. We also measured wind speed and direction, and PM(2.5) concentration as a function of distance from road. Average concentrations are 21-46% higher in the low- than in the middle-income neighborhood, and exhibit differing spatiotemporal patterns. For example, in the middle-income neighborhood, median concentrations are higher near-road than not near-road (56 versus 50 μg m(-3)); in the low-income neighborhood, the reverse holds (68 μg m(-3) near-road, 74 μg m(-3) not near-road), likely because of within-neighborhood residential emissions (e.g., cooking; trash combustion). A moving-average subtraction method used to infer local- versus urban-scale emissions confirms that local emissions are greater in the low-income neighborhood than in the middle-income neighborhood; however, relative contributions from local sources vary by time-of-day. Real-time relative humidity correction factors are important for accurately interpreting real-time nephelometer data.     

Comparison of light scattering devices and impactors for particulate measurements in indoor,outdoor, and personal environments

Short-term monitoring of individual particulate matter (PM) exposures on subjects and inside residences in health effect studies have been sparse due to the lack of adequate monitoring devices. The recent development of small and portable light scattering devices, including the Radiance nephelometer (neph) and the personal DataRAM (pDR) has made this monitoring possible. This paper evaluates the performance of both the passive pDR and neph (without any size fractionation inlet) against measurements from both Harvard impactors (HI2.5) and Harvard personal environmental monitors (HPEM2.5) for PM2.5 in indoor, outdoor, and personal settings. These measurements were taken at the residences and on the person of nonsmoking elderly subjects across the metropolitan Seattle area and represent a wide range of light scattering measurements directly related to exposures and health effects. At low PM levels, nephs provided finer resolution and more precise measurements (precision = 3-8% and uncertainty = 2.8 x 10(-7) m(-1) or <1 microg/m3) than the pDRs. The unbiased precision of pDRs above 10 microg/m3 is around 5% (with an unbiased uncertainty of 4.4 microg/m3). The 24-h average responses of the pDR and neph, as compared to 24-h integrated gravimetric measurements, are not affected by indoor sources of PM. When regressed against 24-h gravimetric measurements, nephs showed higher coefficients of determination (R2 = 0.81-0.93) than pDRs (R2 = 0.77-0.84). The default mass calibration on the pDRs generally overestimated indoor HI2.5 measurements by 56%. When carried by subjects, the pDR overestimated the HPEM2.5 measurements by approximately 27%. Collocated real-time indoor nephs and pDRs at diverse residential sites had varied coefficients of determination across homes (R2 = 0.75-0.96), and the difference between pDR and neph responses increased during cooking hours. This difference was larger during baking or frying episodes than during other cooking or cleaning activities. Relative humidity, ranging between 25% and 64% indoors in our study, was not a significant factor affecting the differences in neph or pDR response. In summary, for nonsmoking residences, the mass scattering efficiency (m2/g) of a stationary indoor neph on a 24-h basis does not vary by residence, including residences with and without cooking activities. This is also true forthe pDR. These same stationary indoor pDRs and nephs correlate well with each other, even on a 10-min basis, in the absence of indoor source activities. The fact that these activities comprised a relatively small percentage (cooking + cleaning = 2.3%) of the overall sampling time meant that the overall correlation between these two instruments for all time periods was good. However, when examining the cooking and cleaning periods separately, the correlation was not very good. Thus, during these short-term PM episodes, the 24-h average calibrations versus gravimetric mass should be used with caution. Both devices should be potentially useful in future exposure assessment and health effects studies.     

Emission factors, size distributions, and emission inventories of carbonaceous particulate matter from residential wood combustion in rural China

Published emission factors (EFs) often vary significantly, leading to high uncertainties in emission estimations. There are few reliable EFs from field measurements of residential wood combustion in China. In this study, 17 wood fuels and one bamboo were combusted in a typical residential stove in rural China to measure realistic EFs of particulate matter (PM), organic carbon (OC), and elemental carbon (EC), as well as to investigate the influence of fuel properties and combustion conditions on the EFs. Measured EFs of PM, OC, and EC (EF(PM), EF(OC), and EF(EC), respectively) were in the range of 0.38-6.4, 0.024-3.0, and 0.039-3.9 g/kg (dry basis), with means and standard derivation of 2.2 ± 1.2, 0.62 ± 0.64, and 0.83 ± 0.69 g/kg, respectively. Shrubby biomass combustion produced higher EFs than tree woods, and both species had lower EFs than those of indoor crop residue burning (p < 0.05). Significant correlations between EF(PM), EF(OC), and EF(EC) were expected. By using a nine-stage cascade impactor, it was shown that size distributions of PM emitted from tree biomass combustions were unimodal with peaks at a diameter less than 0.4 μm (PM(0.4)), much finer than the PM from indoor crop residue burning. Approximately 79.4% of the total PM from tree wood combustion was PM with a diameter less than 2.1 μm (PM(2.1)). PM size distributions for shrubby biomasses were slightly different from those for tree fuels. On the basis of the measured EFs, total emissions of PM, OC, and EC from residential wood combustion in rural China in 2007 were estimated at about 303, 75.7, and 92.0 Gg.     

Daily and peak 1 h indoor air pollution and driving factors in a rural Chinese village

We investigate wintertime indoor air quality and personal exposures to carbon monoxide (CO) in a rural village in Jilin province, where relatively homogeneous climatic and sociocultural factors facilitate investigation of household structural, fuel-related, and behavioral determinants of air pollution as well as relationships between different measures of air quality. Our time-resolved wintertime measurements of carbon monoxide and respirable particles (RSP) enable exploration of peak pollution periods in a village in Jilin Province, China, characterized by household use of both coal and biomass, as well as several "improved" (gas or electric) fuels. Our data indicate a 6-fold increase in peak 1 h PM (1.9 mg/m3) concentrations relative to 24 h mean PM (0.31 mg/m3). Peak 1 h CO concentrations (20.5 ppm) routinely approached and often (27%) exceeded the World Health Organization's 1 h guideline of 26 ppm, although the vast majority (95%) of kitchens were within China's residential indoor air quality guideline for CO on a 24 h basis. Choice of heating fuel and household smoking status were significant predictors of indoor air quality. Whether solid or "improved" (gas or electric) fuel was used for cooking had an even stronger effect, but in the opposite direction from expected, on both peak and daily average measures of air pollution. Peak pollution period concentrations of CO and PM were strongly correlated to daily concentrations of CO and RSP, respectively. Our results suggestthat due to the primary role of heating as a determinant of wintertime indoor air quality in northern Chinese villages, health-oriented interventions limited to provision of improved cooking fuel are insufficient. Our results illustrate that peak pollution periods may routinely exceed exposure regulations and evacuation limits, although this and previous studies document typical 24 h CO concentrations in rural Chinese kitchens to be within guidelines. Within a given village and for a given pollutant, daily pollutant concentrations may be strong predictors of peak pollution period concentrations.     

Estimation of size-resolved ambient particle density based on the measurement of aerosol number, mass, and chemical size distributions in the winter in beijing

Simultaneous measurements of aerosol size, distribution of number, mass, and chemical compositions were conducted in the winter of 2007 in Beijing using a Twin Differential Mobility Particle Sizer and a Micro Orifice Uniform Deposit Impactor. Both material density and effective density of ambient particles were estimated to be 1.61 ± 0.13 g cm(-3) and 1.62 ± 0.38 g cm(-3) for PM(1.8) and 1.73 ± 0.14 g cm(-3) and 1.67 ± 0.37 g cm(-3) for PM(10). Effective density decreased in the nighttime, indicating the primary particles emission from coal burning influenced the density of ambient particles. Size-resolved material density and effective density showed that both values increased with diameter from about 1.5 g cm(-3) at the size of 0.1 μm to above 2.0 g cm(-3) in the coarse mode. Material density was significantly higher for particles between 0.56 and 1.8 μm during clean episodes. Dynamic Shape Factors varied within the range of 0.95-1.13 and decreased with particle size, indicating that coagulation and atmospheric aging processes may change the shape of particles.     

Determination of the sources of indoor PM2.5 in Amsterdam and Helsinki

Daily PM2.5 samples were repeatedly collected (1-8 times) in the homes of elderly nonsmoking individuals with coronary heart disease in Amsterdam, The Netherlands (33 individuals) and Helsinki, Finland (44 individuals). Sources of indoor PM2.5 were evaluated using a two-way multilinear engine model. Because the indoor elemental data lacked a traffic marker, separation of traffic related PM was attempted by combining the indoor data with fixed site outdoor data that also contained NO. Six outdoor sources, including long-range transport (LRT), urban mixture, oil combustion, traffic, sea-salt, and soil were identified, and three indoor sources were resolved: resuspension, potassium-rich and copper-rich sources. The average contribution of the indoor factors was 6% (1.1 microg m(-3)) and 22% (2.4 microg m(-3)) in Amsterdam and Helsinki, respectively. The highest longitudinal correlations between source-specific outdoor and indoor PM2.5 concentrations were found for LRT and urban mixture; the median R was above 0.6 for most sources. The longitudinal correlations were lower in Helsinki than in Amsterdam. Indoor-generated PM2.5 was not related to ambient concentrations. We conclude that using outdoor and indoor data together improved the source apportionment of indoor PM2.5. The results support the use of fixed site outdoor measurements in epidemiological time-series studies on outdoor air pollution.     

Household concentrations and exposure of children to particulate matter from biomass fuels in The Gambia

Particulate matter (PM) is an important metric for studying the health effects of household air pollution. There are limited data on PM exposure for children in homes that use biomass fuels, and no previous study has used direct measurement of personal exposure in children younger than 5 years of age. We estimated PM(2.5) exposure for 1266 children in The Gambia by applying the cookhouse PM(2.5)-CO relationship to the child's CO exposure. Using this indirect method, mean PM(2.5) exposure for all subjects was 135 ± 38 μg/m(3); 25% of children had exposures of 151 μg/m(3) or higher. Indirectly estimated exposure was highest among children who lived in homes that used firewood (collected or purchased) as their main fuel (144 μg/m(3)) compared to those who used charcoal (85 μg/m(3)). To validate the indirect method, we also directly measured PM(2.5) exposure on 31 children. Mean exposure for this validation data set was 65 ± 41 μg/m(3) using actual measurement and 125 ± 54 μg/m(3) using the indirect method based on simultaneously-measured CO exposure. The correlation coefficient between direct measurements and indirect estimates was 0.01. Children in The Gambia have relatively high PM(2.5) exposure. There is a need for simple methods that can directly measure PM(2.5) exposure in field studies.     

Temporal trends in atmospheric PM₂.₅, PM₁₀, elemental carbon, organic carbon, water-soluble organic carbon, and optical properties: impact of biomass burning emissions in the Indo-Gangetic Plain

The first simultaneous measurements and analytical data on atmospheric concentrations of PM(2.5), PM(10), inorganic constituents, carbonaceous species, and their optical properties (aerosol optical depth, AOD; absorption coefficient, b(abs); mass absorption efficiency, σ(abs); and single scattering albedo, SSA) from an urban site (Kanpur) in the Indo-Gangetic Plain are reported here. Significantly high aerosol mass concentration (>100 μg m(-3)) and AOD (> 0.3) are seen as a characteristic feature throughout the sampling period, from October 2008 to April 2009. The temporal variability in the mass fractions of carbonaceous species (EC, OC, and WSOC) is pronounced during October-January when emissions from biomass burning are dominant and OC is a major constituent (～30%) of PM(2.5) mass. The WSOC/OC ratio varies from 0.21 to 0.65, suggesting significant contribution from secondary organic aerosols (SOAs). The mass fraction of SO(4)(2-) in PM(2.5) (Av: 12.5%) exceeds that of NO(3)(-) and NH(4)(+). Aerosol absorption coefficient (@ 678 nm) decreases from 90 Mm(-1) (in December) to 20 Mm(-1) (in April), and a linear regression analysis of the data for b(abs) and EC (n = 54) provides a measure of the mass absorption efficiency of EC (9.6 m(2) g(-1)). In contrast, scattering coefficient (@ 678 nm) increases from 98 Mm(-1) (in January) to 1056 Mm(-1) (in April) and an average mass scattering efficiency of 3.0 ± 0.9 m(2) g(-1) is obtained for PM(10) samples. The highest b(scat) was associated with the dust storm event (April 17, 2009) over northern Iraq, eastern Syria, and southern Turkey; thus, resulting in high SSA (0.93 ± 0.02) during March-April compared to 0.82 ± 0.04 in October-February. These results have implications to large temporal variability in the atmospheric radiative forcing due to aerosols over northern India.     

Influence of temperature on the emission of di-(2-ethylhexyl)phthalate (DEHP) from PVC flooring in the emission cell FLEC

Emissions of di-(2-ethylhexyl) phthalate (DEHP) from one type of polyvinylchloride (PVC) flooring with approximately 13% (w/w) DEHP as plasticizer were measured in the Field and Laboratory Emission Cell (FLEC). The gas-phase concentrations of DEHP versus time were measured at air flow rate of 450 mL·min(-1) and five different temperatures: 23 °C, 35 °C, 47 °C, 55 °C, and 61 °C. The experiments were terminated two weeks to three months after steady-state was reached and the interior surface of the FLECs was rinsed with methanol to determine the surface concentration of DEHP. The most important findings are (1) DEHP steady-state concentrations increased greatly with increasing temperature (0.9 ± 0.1 μg·m(-3), 10 ± 1 μg·m(-3), 38 ± 1 μg·m(-3), 91 ± 4 μg·m(-3), and 198 ± 5 μg·m(-3), respectively), (2) adsorption to the chamber walls decreased greatly with increasing temperature (measured partition coefficient between FLEC air and interior surface are: 640 ± 146 m, 97 ± 20 m, 21 ± 5 m, 11 ± 2 m, and 2 ± 1 m, respectively), (3) gas-phase DEHP concentration in equilibrium with the vinyl flooring surface is close to the vapor pressure of pure DEHP, and (4) with an increase of temperature in a home from 23 to 35 °C, the amount of DEHP in the gas- and particle-phase combined is predicted to increase almost 10-fold. The amount in the gas-phase increases by a factor of 24 with a corresponding decrease in the amount on the airborne particles.     

微细化处理对食用菌五谷面条蒸煮及质构特性的影响

研究微细化处理食用菌五谷面粉对其面条蒸煮及质构的影响,采用微粉碎技术对食用菌五谷混合粉进行处理,并对食用菌五谷面条蒸煮特性、质构特性、表面微观结构等进行检测。结果表明最佳物料粒度为160目(0.097 mm),其体积等效粒径为70.5μm。微细化处理后的混合粉粒径主要分布在3~40μm和40~500μm两个区间内,微细化处理后食用菌五谷面条的最佳蒸煮时间为(13.45±0.26)min;复水率、干物质吸水率分别增加到(93.20±2.28)%、(128.63±2.57)%,干物质损失率、熟断条率分别降低为(6.72±0.09)%、(5.00±0.32)%。质地剖面分析(texture profile analysis,TPA)实验结果表明面条延展性为(-4.09±0.10)g/s,硬度、黏性分别降低至(310.39±7.39)g、(-4.87±0.65)g·s,咀嚼性增加到(102.14±3.31)g·s;拉伸实验结果表明160目(0.097 mm)食用菌五谷面条拉断力最大,为(19.43±0.18)N,拉伸距离为(53.90±0.87)mm。扫描电子显微镜观察结果表明,随着微细化程度增加,面条表观改善,结构变得更加致密光滑,孔隙相对减少,有利于提高食用菌五谷面条的蒸煮耐性,改善其质构持性。     

Assessment of noise and heavy metals (Cr, Cu, Cd, Pb) in the ambience of the production line for recycling waste printed circuit boards

The crush-pneumatic separation-corona electrostatic separation production line provides a feasible method for industrialization of waste printed circuit boards (PCBs) recycling. To determine the potential environmental contamination in the automatic line workshop, noise and heavy metals (Cr, Cu, Cd, Pb) in the ambience of the production line have been evaluated in this paper. The mean noise level in the workshop has been reduced from 96.4 to 79.3 dB since the engineering noise control measures were employed. Noise whose frequency ranged from 500 to 1000 Hz is controlled effectively. The mass concentrations of TSP and PM(10) in the workshop are 282.6 and 202.0 μg/m(3), respectively. Pb (1.40 μg/m(3)) and Cu (1.22 μg/m(3)) are the most enriched metals in TSP samples followed by Cr (0.17 μg/m(3)) and Cd (0.028 μg/m(3)). The concentrations of Cu, Pb, Cr, and Cd in PM(10) are 0.88, 0.56, 0.12, and 0.88 μg/m(3), respectively. Among the four metals, Cr and Pb are released into the ambience of the automatic line more easily in the crush and separation process. Health risk assessment shows that noncancerous effects might be possible for Pb (HI = 1.45), and noncancerous effects are unlikely for Cr, Cu, and Cd. The carcinogenic risks for Cr and Cd are 3.29 × 10(-8) and 1.61 × 10(-9), respectively. It indicates that carcinogenic risks on workers are relatively light in the workshop. These findings suggest that this technology is advanced from the perspective of environmental protection in the waste PCBs recycling industry.     

Source contributions to atmospheric gases and particulate matter in the southeastern United States

A new approach for determining the contributions of emission sources to concentrations of particulate matter and gases is developed using the chemical mass balance (CMB) method and the U.S. EPA's National Emission Inventory (NEI). The approach apportions combined gas-phase and condensed-phase concentrations of individual compounds as well as PM(2.5) mass. Because the NEI is used to provide source emission profiles for CMB analysis, the method generates information on the consistency of the NEI with ambient monitoring data. The method also tracks secondary species to primary source emissions, permitting a more complete accounting of the impact of aggregated source types on PM(2.5) mass concentrations. An example application is presented using four years of monitoring data collected at eight sites in the Southeastern Aerosol Research and Characterization (SEARCH) network. Including both primary and secondary species, area sources contributed 2.0-3.7 μg m(-3) (13-26%), point sources contributed 3.0-4.6 μg m(-3) (22-33%), and mobile sources contributed 1.0-6.0 μg m(-3) (9-42%) to mean PM(2.5) mass concentrations. Whereas the NEI generally accounts for the ambient concentrations of gases and particles, certain anomalies are identified, especially related to carbonaceous compounds and dust.     

Microfabricated gas chromatograph for on-site determinations of TCE in indoor air arising from vapor intrusion. 2. Spatial/temporal monitoring

We demonstrate the use of two prototype Si-microfabricated gas chromatographs (μGC) for continuous, short-term measurements of indoor trichloroethylene (TCE) vapor concentrations related to the investigation of TCE vapor intrusion (VI) in two houses. In the first house, with documented TCE VI, temporal variations in TCE air concentrations were monitored continuously for up to 48 h near the primary VI entry location under different levels of induced differential pressure (relative to the subslab). Concentrations ranged from 0.23 to 27 ppb by volume (1.2-150 μg/m(3)), and concentration trends agreed closely with those determined from concurrent reference samples. The sensitivity and temporal resolution of the measurements were sufficiently high to detect transient fluctuations in concentration resulting from short-term changes in variables affecting the extent of VI. Spatial monitoring showed a decreasing TCE concentration gradient with increasing distance from the primary VI entry location. In the second house, with no TCE VI, spatial profiles derived from the μGC prototype data revealed an intentionally hidden source of TCE within a closet, demonstrating the capability for locating non-VI sources. Concentrations measured in this house ranged from 0.51 to 56 ppb (2.7-300 μg/m(3)), in good agreement with reference method values. This first field demonstration of μGC technology for automated, near-real-time, selective VOC monitoring at low- or subppb levels augurs well for its use in short- and long-term on-site analysis of indoor air in support of VI assessments.     

Vacuum cleaner emissions as a source of indoor exposure to airborne particles and bacteria

Vacuuming can be a source of indoor exposure to biological and nonbiological aerosols, although there are few data that describe the magnitude of emissions from the vacuum cleaner itself. We therefore sought to quantify emission rates of particles and bacteria from a large group of vacuum cleaners and investigate their potential determinants, including temperature, dust bags, exhaust filters, price, and age. Emissions of particles between 0.009 and 20 μm and bacteria were measured from 21 vacuums. Ultrafine (<100 nm) particle emission rates ranged from 4.0 × 10(6) to 1.1 × 10(11) particles min(-1). Emission of 0.54-20 μm particles ranged from 4.0 × 10(4) to 1.2 × 10(9) particles min(-1). PM(2.5) emissions were between 2.4 × 10(-1) and 5.4 × 10(3) μg min(-1). Bacteria emissions ranged from 0 to 7.4 × 10(5) bacteria min(-1) and were poorly correlated with dust bag bacteria content and particle emissions. Large variability in emission of all parameters was observed across the 21 vacuums, which was largely not attributable to the range of determinant factors we assessed. Vacuum cleaner emissions contribute to indoor exposure to nonbiological and biological aerosols when vacuuming, and this may vary markedly depending on the vacuum used.     

Waterpipe-associated particulate matter emissions.

Waterpipe tobacco smoking is increasingly common worldwide, and evidence about its harmful effects to smokers is emerging. However, no studies have investigated the potential exposure of nonsmokers to waterpipe smoke. We measured particulate matter (PM) emissions (PM2.5, PM10) before and during laboratory sessions in which 20 individuals used a waterpipe to smoke tobacco and 20 individuals smoked a cigarette (10 for each particle-size/smoking-method), as well as 10 waterpipe and 10 cigarette smoldering sessions (i.e., without a smoker). A TSI-SidePak aerosol monitor obtained PM2.5, PM10 background, smoking, and maximum levels. Mean PM2.5 rose 447% for waterpipe (from 48 microg/m3 background to 264 microg/m3 smoking), and by 501% for cigarettes (from 44 microg/m3 to 267 microg/m3), whereas mean PM10 rose by 563% for waterpipe (from 55 microg/m3 to 365 microg/m3), and by 447% for cigarettes (from 52 microg/m3 to 287 microg/m3) (p<.05 for all). The increase in PM during cigarette smoking was due primarily to PM2.5, given that the proportion of PM2.5 from total PM10 increase was 95% compared with 70% for waterpipe (p<.05). Maximum PM2.5 was 908 microg/m3 for waterpipe and 575 microg/m3 for cigarettes, whereas maximum PM10 was 1052 microg/m3 for waterpipe and 653 microg/m3 for cigarettes. Mean PM2.5 and PM10 smoldering levels did not differ from background for waterpipe but were significantly higher for cigarettes (PM2.5: 33-190 microg/m3; PM10: 42-220 microg/m3). Policymakers considering clean air regulations should include waterpipe tobacco smoking, and the public should be warned about this source of smoke exposure.     

甘草黄酮对大气细颗粒物PM2.5引起肺泡巨噬细胞损伤的保护作用

目的:研究甘草黄酮对大气细颗粒物PM2.5(SRM 2786)导致的大鼠肺泡巨噬细胞(NR8383)损伤的保护作用。方法:实验分为对照组、模型组(125 μg/mL SRM 2786)与不同浓度甘草黄酮给药组(3.125、6.25、12.5、25 μg/mL+125 μg/mL SRM 2786),药物作用24 h后分别用MTT法检测细胞存活率、细胞形态观察、酶联免疫法(Elisa)检测细胞上清液肿瘤坏死因子α(TNF-α)、白介素6(IL-6)及白介素1β(IL-1β)的含量、各组细胞NO和ROS释放及细胞中SOD活性和GSH-PX含量。结果:相较于对照组,125 μg/mL SRM 2786诱导可减少细胞贴璧生长且显著降低细胞存活率、SOD活性和GSH-PX含量、提高TNF-α、IL-6及IL-1β三种细胞因子的释放及细胞ROS和NO释放(p<0.01);而3.125~25 μg/mL甘草黄酮可使大部分悬浮细胞重新贴璧且显著提高下降的细胞存活率,显著抑制SRM 2786诱导的炎症细胞因子的释放和ROS释放、显著提高SOD活性及GSH-PX含量(p<0.05或 p<0.01),6.25~25 μg/mL甘草黄酮可显著降低SRM 2786导致的NO释放(p<0.05或p<0.01)。结论:甘草黄酮可显著提高由细颗粒物SRM 2786降低的细胞存活率和提高抗氧化酶活性、抑制炎性因子释放及氧化应激,其机制可能与其抗炎性损伤和氧化损伤有关。     

Development and evaluation of a personal particulate organic and mass sampler

Accurate measurement of personal exposure to particulate matter and its constituents requires samplers that are accurate, compact, lightweight, inexpensive, and convenient to use. The personal particulate organic and mass sampler (PPOMS) has been developed to meet these criteria. The PPOMS uses activated carbon-impregnated foam as a combined 2.5-microm size-selective inlet and denuder for assessment of fine particle mass and organic carbon. Proof of the PPOMS concept has been established by comparing mass and organic carbon in particles collected with collocated samplers in Seattle, at a central outdoor site, and in residences. Daily particulate mass concentrations averaged 10.0 +/- 5.2, 12.0 +/- 5.3, and 11.2 +/- 5.1 microg m(-3) for the Federal Reference Method, the Harvard Personal Exposure Monitor, and the PPOMS, respectively, for 10 24-h sampling periods. During a series of PM2.5 indoor organic carbon (OC) measurements from single quartz filters, the apparent indoor OC averaged 7.7 +/- 0.8 microg of C m(-3), which was close to the indoor PM2.5 mass from collocated Teflon filters (7.3 +/- 2.3 microg of C m(-3)), indicating the presence of a large positive OC artifact. In collocated measurements, the PPOMS eliminated this artifact just as well as the integrated gas and particle sampler that incorporated a macroreticular polystyrene-divinylbenzene (XAD-4) resin-coated denuder, yielding OC concentrations of 2.5 +/- 0.4 and 2.4 +/- 1.0 microg of C m(-3), respectively. Thermal analysis for OC indicated that the indoor positive artifact was due to adsorption of gas-phase semivolatile organic compounds (SVOC). This study shows that the PPOMS design provides a 2.5-microm size-selective inlet that also prevents the adsorption of gas-phase SVOC onto quartz filters, thus eliminating the filter positive artifact The PPOMS meets a significant current challenge for indoor and personal sampling of particulate organic carbon. The PPOMS design can also simplify accurate ambient sampling for PM2.5.     

Chemical characterization and source apportionment of fine and coarse particulate matter inside the refectory of Santa Maria Delle Grazie Church, home of Leonardo Da Vinci's "Last Supper"

The association between exposure to indoor particulate matter (PM) and damage to cultural assets has been of primary relevance to museum conservators. PM-induced damage to the "Last Supper" painting, one of Leonardo da Vinci's most famous artworks, has been a major concern, given the location of this masterpiece inside a refectory in the city center of Milan, one of Europe's most polluted cities. To assess this risk, a one-year sampling campaign was conducted at indoor and outdoor sites of the painting's location, where time-integrated fine and coarse PM (PM(2.5) and PM(2.5-10)) samples were simultaneously collected. Findings showed that PM(2.5) and PM(2.5-10) concentrations were reduced indoors by 88 and 94% on a yearly average basis, respectively. This large reduction is mainly attributed to the efficacy of the deployed ventilation system in removing particles. Furthermore, PM(2.5) dominated indoor particle levels, with organic matter as the most abundant species. Next, the chemical mass balance model was applied to apportion primary and secondary sources to monthly indoor fine organic carbon (OC) and PM mass. Results revealed that gasoline vehicles, urban soil, and wood-smoke only contributed to an annual average of 11.2 ± 3.7% of OC mass. Tracers for these major sources had minimal infiltration factors. On the other hand, fatty acids and squalane had high indoor-to-outdoor concentration ratios with fatty acids showing a good correlation with indoor OC, implying a common indoor source.     

Measurement of N2, N2O, NO, and CO2 emissions from soil with the gas-flow-soil-core technique

Here we describe a newly designed system with three stand-alone working incubation vessels for simultaneous measurements of N(2), N(2)O, NO, and CO(2) emissions from soil. Due to the use of a new micro thermal conductivity detector and the redesign of vessels and gas sampling a so-far unmatched sensitivity (0.23 μg N(2)-N h(-1) kg(-1) ds or 8.1 μg N(2)-N m(-2) h(-1)) for detecting N(2) gas emissions and repeatability of experiments could be achieved. We further tested different incubation methods to improve the quantification of N(2) emission via denitrification following the initialization of soil anaerobiosis. The best results with regard to the establishment of a full N balance (i.e., the changes in mineral N content being offset by simultaneous emission of N gases) were obtained when the anaerobic soil incubation at 25 °C was preceded by soil gas exchange under aerobic conditions at a lower incubation temperature. The ratios of N and C gas emission changed very dynamically following the initialization of anaerobiosis. For soil NO(3)(-) contents of 50 mg N kg(-1) dry soil (ds) and dissolved organic carbon (DOC) concentrations of approximately 300 mg C kg(-1) ds, the cumulative emissions of N(2), N(2)O, and NO were 24.3 ± 0.1, 12.6 ± 0.4, and 10.1 ± 0.3 mg N kg(-1) ds, respectively. Thus, N gas emissions accounted (on average) for 46.2% (N(2)), 24.0% (N(2)O), and 19.2% (NO) of the observed changes in soil NO(3)(-). The maximum N(2) emission reached 1200 μg N h(-1) kg(-1) ds, whereas the peak emissions of N(2)O and NO were lower by a factor of 2-3. The overall N(2):N(2)O and NO:N(2)O molar ratios were 1.6-10.0 and 1.6-2.3, respectively. The measurement system provides a reliable tool for studying denitrification in soil because it offers insights into the dynamics and magnitude of gaseous N emissions due to denitrification under various incubation conditions.