Method for Estimating Size-Specific Particulate Emission Inventories

Increasing evidence on the detrimental health effects of suspended fine particulates has prompted the introduction of new ambient air quality standards for particles with diameters smaller than 2.5 and∕or 10 μm and has created the need for size-specific inventories. To address this need, “generic” cumulative weight fraction data have been fitted with lognormal particle size distributions, and the resulting mean diameter dm and standard deviation σg values compiled for many sources of practical interest. In addition, nomographs are developed for assessing the mass fraction of particles with diameters <2.5, 6, 10, 15, and 30 μm as a function of the applicable dm and σg. The above data and tools allow easy extension of total particulate matter emission inventories for uncontrolled sources into size-specific ones. Supplemented with published typical efficiencies of control systems in the ranges 0–2.5, 2.5–6, and 6–10 μm, they also allow easy compilation of approximate size-specific inventories for controlled sources. In addition, used in conjunction with graphical models for selected control systems that predict the total efficiency and lognormal size distribution of penetrating particles, they offer a unique rigorous approach for size-specific inventories from controlled sources.     

Airborne small particles as a cause of pulmonary diseases and excessive mortality?

The paper reviews the available literature with regard to human health effects of fine particulate matter (PM10, PM2.5) from a Danish perspective. Fine particulate matter is not routinely measured in any Danish air pollution monitoring programme. Preliminary surveys show elevated PM2.5 levels in Copenhagen corresponding to levels found in other cities in Europe and the USA, and a close relationship between outdoor and indoor concentrations. It has been roughly estimated that about 400 people in the Greater Copenhagen area may suffer a premature death due to airborne fine particulate matter. A limited number of Danish studies support the view that health effects (respiratory symptoms and increased medication) can be observed in sensitive city populations at air pollution levels well below international air quality standards.     

Observation on Particulate Matter over a Period of 3 Years at Kaikhali (22.022°N and 88.614°E) inside a Special Mangrove Ecosystem: Sundarbans

Measurement of particulates [respirable particulate matter (RPM or PM10), fine RPM (PM2.5), non-RPM (NRPM), and total suspended particulate matter (TSPM)] were carried out on a campaign basis over a period of 3 years (2003–2006) at Kaikhali (22.022°N and 88.614°E) inside one of the world’s largest mangrove delta region—“The Sundarbans.” Considering the toxic potential of the particulate fractions, the foremost objective of this study was to determine the particulate concentrations during different parts of the year as well as to ascertain the trend of occurrence of the particulate fractions in an area of rich and unique biodiversity. Moreover, as the area had no past records on particulate data over a decade, the other important objective of the study was to prepare substantial database for the area for the present time. The average range of PM10, PM2.5, NRPM, and TSPM for the period from 2003–2006 has been found to be (57–118), (35–80), (10–25), and (73–135)?μg?m?3 respectively. The data obtained for the finer particulate fractions have been compared with some previous studies in India. In addition to the particulate fractions, meteorological parameters such as wind speed, wind direction, and temperature were also recorded to accomplish proper interpretation of the data. The requisite statistical parameters (standard deviation, average, and range) for the particulate fractions have also been calculated.     

基于机器学习的北京市PM2.5浓度预测模型及模拟分析

对北京市周边8个点多个压力高度的温度、湿度和风速数据, 以及北京市PM2.5污染数据进行了分析和归一化处理, 建立了反向传播神经网络(back propagation, BP)、卷积神经网络(convolutional neural network, CNN) 和长短期记忆模型(long short-term memory, LSTM) 对上述气象数据和污染数据进行训练, 训练结果表明: 反向传播神经网络模型和卷积神经网络模型对未来1 h的PM2.5污染等级的预测准确率较低, 而长短期记忆模型的准确率较高.使用长短期记忆模型预测未来1 h的PM2.5污染值与实际值十分接近, 表明北京市的PM2.5污染与其周边地区的气象条件关系密切.通过利用长短期记忆模型对不同压力高度的气象数据进行训练和对比, 得出在利用气象数据预测污染时, 仅使用近地面气象数据比使用多个高度上的气象数据更加准确.      

铁矿烧结过程微细颗粒物（PM10/PM2.5）排放特性及研究进展

铁矿烧结工序是现代钢铁生产流程中必不可少的环节,但又是钢铁工业最大的微细颗粒物(PM10和PM2.5)排放源,占总排放量的40％左右.阐述了铁矿烧结过程PM10和PM2.5的排放特性,颗粒形貌及其物理化学性质;综述了国内外关于烧结过程微细颗粒物减排的最新研究进展,提出了烧结过程微细颗粒物减排研究的发展方向.     

室内空气中可吸入颗粒物的监测与研究

作者介绍室内空气中颗粒物的危害与来源。通过对居室空气中可吸入颗粒物（PM10）及总悬浮颗粒物（TSP）监测，应用监测结果分析了一般居室污染中可吸入颗粒物的污染情况及居住环境对室内PM10浓度的影响，同时研究了空气中PM10浓度与TSP浓度的关系。     

铁矿烧结过程微细颗粒物排放行为

 采用ELPI+设备(荷电低压撞击器)对铁矿烧结过程微细颗粒物进行在线检测与采样,利用场发射扫描电子显微镜(FESEM EDS)对采集的颗粒物形貌特征进行分析,研究铁矿烧结过程中微细颗粒物的排放行为。研究结果表明,PM10大量释放集中在烧结升温段,且颗粒物质量浓度与数目浓度在粒径分布上有较大差异,其中质量浓度峰值区间为5.37～10.00 μm,数目浓度峰值区间为0.10～0.16 μm;形貌特征上,微细颗粒物呈规则的球形、方块形和片状;不同粒径物质组成差异明显,其中颗粒物中的K、Na主要以KCl和NaCl的形式存在,含量随颗粒物粒级的增大而略有降低。     

Personal sampling of particles in adults: relation among personal, indoor, and outdoor air concentrations

To investigate the validity of outdoor particulate matter with a 50% cutoff diameter of 10-microm (PM10) concentrations as a measure of exposure in time series studies, the association between personal and outdoor concentrations, within subjects, over time was investigated. Repeated measurements of personal, indoor, and outdoor PM10 were conducted among 37 nonsmoking, 50- to 70-year-old adults, living in Amsterdam, Netherlands, 1994. Regression analyses were conducted for each subject separately, and the distribution of the individual regression and correlation coefficients was investigated. Furthermore, the extent to which differences among personal, indoor, and outdoor concentrations could be explained was studied. The median Pearson's R between personal and outdoor concentrations was 0.50. Excluding days with exposure to environmental tobacco smoke (ETS) improved the correlation to a median R of 0.71. The estimated cross-sectional correlations were lower, 0.34 and 0.50, respectively. Outdoor concentrations (mean, 42 microg/m3) exceeded indoor concentrations (mean, 35 microg/m3) but underestimated personal exposures (mean, 62 microg/m3). The major part of the difference between personal and outdoor concentrations could be attributed to exposure to ETS, living along a busy road, and time spent in a vehicle. The results show a reasonably high correlation between personal and outdoor PM10 within individuals, providing support for the use of ambient PM10 concentrations as a measure of exposure in epidemiologic studies linking the day-to-day variation in particulate matter air pollution to the day-to-day variation in health endpoints such as mortality, hospital admissions, respiratory symptoms, and lung function.     

CFD Modeling of Particulate Matter Fate and Pressure Drop in a Storm-Water Radial Filter

This study examined a common form of filtration, a passive radial cartridge filter (RCF) system, to physically separate hetero-disperse particulate matter in rainfall-runoff. The RCF tested utilizes aluminum-oxide coated media with a uniform pumice substrate (d50m = 3.56?mm) gradation. To examine the RCF, this study applied laser diffraction and real-time pressure sensor measurements to validate a computational fluid dynamics (CFD) model to predict particle separation and filter head loss for hetero-disperse particulate matter (PM). Filter hydrodynamics are resolved using a macroscopic approach for the porous media with a k-ε turbulence model coupled with the Ergun equation. PM fate was resolved using a discrete phase model. CFD results closely followed measured data for filtration and head-loss response for all flow rates. With influent PM at 200?mg/L (d50m = 16.3?μm), effluent PM ranged from 32?to?57?mg/L for surface loading rates of 24?to?189?L/m2?min, respectively. There was agreement between measured and modeled data for effluent PM and head loss. CFD postprocessing provided added insight into the mechanistic behavior of the RCF by means of three-dimensional hydraulic profiles, particle trajectories, and pressure distributions, illustrating that a RCF is nonuniformly loaded. As part of design and regulation, such physical testing coupled with modeling is a required precursor to uncontrolled field testing, regular maintenance and certification of a BMP.     

Prevention Efficiencies of Woven Straw to Reduce PM10 Emissions from Exposed Area

Woven straw has been demonstrated to be a cheap and effective method to prevent fugitive particular matter (PM), which is a typical air pollution source emitted from the exposed area, like farmland or a construction site. From the engineering application point of view, an approach using dimensionless analysis with a multivariable regression method based on experimental data would be worth exploring to predict the prevention efficiencies of woven straw to reduce the fugitive PM10 (PM sized less than 10?μm). A series of field-analogous experiments were carried out to continuously measure PM10 using β-attenuation particle monitors in an artificial wind tunnel system. It was found that the prevention efficiencies of woven straw to reduce PM10 is significantly dependent on the coverage ratio of woven straw, and the maximum prevention efficiency of PM10 is about 42%. It is emphasized that the prevention efficiency approaches zero as the coverage ratio is less than about 40%. This implies that PM10 reduction was inefficient if the exposed area was not covered enough with woven straw. Another point of interest is that total elimination of PM10 emission is not possible using full coverage woven straw. The effects of wind velocity, silt content, and moisture on prevention efficiency are also discussed in this paper. Correlated with major parameters, a useful equation is proposed to estimate the prevention efficiencies that would be valid under the appropriate conditions suggested by this work.     

长沙冬季PM2.5、PM10中金属元素的浓度及分布特征

选取长沙县某商业区、居住区、对照区三个区域,研究该区域内的PM_2.5、PM₁₀浓度及其金属元素贡献率,结果表明,空气中PM_2.5、PM₁₀浓度总体呈现商业区>居住区>对照区的趋势,PM_2.5中贡献率最大的5类金属元素为Na、Ca、K、Al和Mg,重金属中贡献率最大的为Cu和Mn;PM₁₀中为Na、Ca、Fe、Al和Mg,重金属中贡献率最大的为Cu和Zn。PM_2.5、PM₁₀中含量最低的重金属元素都为As。     

Total PM Emission Factors for Steel Grit Used in Dry Abrasive Blasting

The performance of an abrasive is dependent on its properties as well as the operating conditions during blasting. This study was undertaken to simulate enclosed blasting operations using steel shot and grit on rusted and painted steel panels; and collect and measure total particulate matter (PM) emissions at commonly used blast pressure and feed rate settings. U.S. EPA source sampling methods were used to sample emissions and estimate uncontrolled total PM emission factors. Regression equations expressing total PM emissions as function of blast pressure and abrasive feed rate were developed to estimate uncontrolled total PM emissions. The results of this study will be helpful in controlling emissions, developing emission inventories, developing best management practices, and selecting process parameters corresponding to minimum emissions for steel shot and grit.     

Rapid Performance Evaluation and Optimal Sizing of Dry Cyclone Separators

Cyclones are generally less efficient than other kinds of equipment, but their simple construction, low energy requirements, and ability to operate at high temperatures and pressures make them attractive for cleaning up gases. Despite the simplicity in construction and operation, complex mathematical formulations are used for predicting the collection efficiency of particles of a given diameter. These must be numerically integrated, along with the inlet particle-size-distribution functions that are appropriate in each application, in order to obtain the overall cyclone efficiency. In this paper, the above cumbersome procedure is simplified through nomographs allowing rapid, yet rigorous, estimation of the overall cyclone efficiencies based on two alternative and well-established approaches and on the sole assumption of a lognormal particle-size distribution. Along with the above, pressure drop and limiting inlet velocity correlations are also considered, and each of the above nomographs is combined with others, providing direct graphical representation of the so far obscure relationships among cyclone diameter, overall efficiency, and gas pressure drop or flow rate. The paper thus affords an overview of cyclone behavior over a wide range of conditions, offering direct solutions to both cyclone performance and optimal cyclone design problems.     

PM2.5 and mortality in long-term prospective cohort studies: cause-effect or statistical associations?

Concentrations of ambient PM2.5 (particulate matter <2.5 microm in aerodynamic diameter) were associated with increased mortality in two prospective cohort studies. In this paper, I assess whether the weight of the evidence supports a causal association. I assumed the study population in each city to have the same exposure; therefore, these are ecologic studies because exposure is at the group level. Health outcome and confounding data are at the individual level. Ambient PM concentrations are inadequate surrogates for personal exposure because they are at the group level and comprise only a small proportion of personal exposure, they change over time, and they constitute only a small proportion of a life span. The strength of association and exposure-response relationships cannot be determined because the ecologic group-level risks of PM2.5 are overestimated 150- to 300-fold based on an analogy with individual-level exposure to inhaled cigarette smoke. Risk estimates may also be high because of confounding from factors such as physical activity and lung function. The evidence is not coherent because the stronger associations are expected to be with morbidity, but instead are with mortality. For example, PM2.5 was associated with mortality but not with measurable reductions in lung function. Biological plausibility is lacking because lifetime exposure of rats to combustion products at concentrations two to three orders of magnitude higher than air pollution levels cause lung overloading but no consistent reduction in survival. Criteria for quantitative risk assessment are not met so the data are not useful for setting air quality standards. The weight of evidence suggests there is no substantive basis for concluding that a cause-effect relationship exists between long-term ambient PM2.5 and increased mortality.     

Mortality and ambient fine particles in southwest Mexico City, 1993-1995

++Epidemiologic studies have focused attention on the health effects of fine particulate air pollutants <2.5 microm in diameter (PM2.5). To further characterize the potential effects of fine particles, we investigated the relationship of air pollution to mortality in Mexico City during 1993-1995. The concentration of PM2.5 was measured on a 24-hr integrated basis; concentrations of NO2 and ozone were measured hourly and reduced to 24-hr means. Daily mortality was determined from death registration records, and Poisson regression was used to model daily death counts as a function of air pollutant levels on the same and previous days, while controlling for temperature and periodic cycles. Without taking other air pollutants into account, a 10 microg/m3 increase in the level of PM2.5 was associated with a 1.4% increase in total mortality, both on the current day and 4 days after exposure [95% confidence interval (CI), 0.2-2.5]. An equivalent increase in PM2.5 was also associated with somewhat larger excesses of deaths among people over 65 years of age and from cardiovascular and respiratory causes, which occurred after a lag of 4 days. The mean concentration of ozone over a 2-day period was associated with a 1.8% increase in mortality from cardiovascular diseases. NO2 was not consistently related to mortality. Fine particles had an independent effect on mortality when modeled simultaneously with other pollutants, and the association of ozone with cardiovascular mortality was strengthened after adjusting for NO2 and PM2.5. These results support previous findings that urban air pollution at current levels leads to excess mortality and suggest that fine particles may play a causal role in producing that excess.     

Does Filtration Efficiency Affect Measurements of Particle Chemical Composition?

A direct method to measure filtration efficiency was developed and used for the determination of the efficiency of a Nuclepore filter. This needs two equivalent filtration systems operated in sequence. The amount of particulate matter collected on each system is measured and introduced in a simple formula. The particulate masses deposited on the filters in each system were measured as total mass, by balance gravimetry, and as individual elemental masses, by PIXE (particle induced X-ray emission). With this very general method it was possible to determine the efficiencies of a 0.4 μm Nuclepore filter operated with a stacked filter unit for particles less than 2.5 μm in total mass and elemental masses. The experiment showed that the efficiency of this filter is very poor for some specific elements, like sulfur, that are concentrated in very small particles.     

Particulate Matter from Stone Crushing Industry: Size Distribution and Health Effects

A cluster of 50 stone crushing units located at Pammal, in suburban Chennai, the capital of Tamil Nadu State, India, is a source of high levels of dust generation in the vicinity of the crushers and in the communities surrounding them. Ambient air quality network consisting of 26 sampling locations were operated to continuously monitor the total and respirable particulate matter concentrations (TSP and PM10). The daily average ambient concentrations of TSP and PM10 varied from 342 to 2,470 and 90 to 1,200?μg/m3, respectively, near the source, while the average concentrations varied from 86 to 257 and 39 to 138?μg/m3 in ambient air. The average PM2.5 concentration varied from 41 to 388?μg/m3 at the source, whereas the concentration varied from 17 to 48?μg/m3 in ambient air. Personal samplers were also employed to quantify the TSP and RPM in the work environment and they varied from 22.5 to 80.5 and 13.5 to 53.7?mg/m3, respectively. Both ambient concentrations and occupational exposure levels exceeded the Indian National Standards at most of the locations. Pulmonary function tests performed on workers showed that the average values of pulmonary function in these workers are significantly lower than the average values reported for normal South Indian healthy males.     

Use of Simulink for Dynamic Air Quality Modeling in Interior Alaska

Interior Alaska has indoor air quality (IAQ) issues similar to those of other far northern communities associated with long cold winters and reduced ventilation rates. We also have some interesting issues associated with elevated radon in homes built in the hills around Fairbanks, as well as elevated particulate levels created by smoke from forest fires that occur in the vast uninhabited portions of the state. To better understand the influences of critical variables such as indoor source strengths and ventilation rates on IAQ associated with forest fires and radon, we have developed a Simulink-based mass conservation model. Using data gathered at two homes in Fairbanks during 2003, we have used this model to predict indoor radon and PM2.5 levels (particles less than 2.5?μm in diameter). We find that we are able to predict both the rise of radon following the shutdown of a radon mitigation system and the variation of indoor PM2.5 by using ventilation rates consistent with what we have measured, PM2.5 source strengths associated with individuals in residences, and penetration and deposition rates compatible with what others have found. We have used situation-specific algorithms for subsurface radon source strength as well as particulate generation associated with cooking.     

Experimental and Field Studies of Type I Settling for Particulate Matter Transported by Urban Runoff

Settling velocity is an important constitutive parameter of particulate matter (PM) transported by runoff. Settling velocity is either explicitly or implicitly utilized when designing or modeling unit operations, and in situ or watershed controls for urban rainfall-runoff. Utilizing two common settling devices, a settling column and an Imhoff cone, settling velocities of discrete noncolloidal particles in source area urban rainfall-runoff were measured. A comparison of settling models applicable to discrete (Type I) PM settling was developed. Models were compared to measured results across the noncohesive silt- and sand-size PM gradation from 2 to 2,000?μm, utilizing measured particle-size distributions (PSDs) and specific gravity. Results indicate that Newton’s Law can reproduce measured settling velocity when measured inputs of PM diameter, specific gravity, and temperature are utilized. Alternative models to Newton’s Law (in the Stokesian regime) did not improve agreement with measured settling velocities determined using PSDs from laser diffraction. Settling velocity distributions using Newton’s Law were applied for two limiting classes of storm events loading a screened hydrodynamic separator (HS) at an urban watershed. Results indicate that for a low flow and high flow event, Newton’s Law and a simple ideal overflow model of the HS could reproduce PM separation and the PSD of eluted PM (2 to ～ 250?μm) within 17% of measured results on a gravimetric basis.     

北京大气颗粒物污染特征及空间分布插值分析

为较好地表征当前北京整个区域大气颗粒物质量浓度随时间尺度的变化及区域分布污染特征,根据北京市35个监测站点获得的2013年3—5月颗粒物质量浓度1 h均值,分析和研究PM_2.5和PM₁₀质量浓度的季节性变化并提高其空间分辨率,在此基础上探讨颗粒物可能的影响因素及污染来源.结果表明,3—5月颗粒物质量浓度具有周期性变化规律和显著相关性,应用MATLAB空间插值算法实现的颗粒物质量浓度区域分布图具有一定精度,可外推并揭示颗粒物区域污染特征.分析表明当前北京颗粒物污染的影响因素有冬末的冷锋和降雪、春季的沙尘和大风、夏初的降雨和湿热等;污染区域则呈现南高北低的特征,污染来源除了本地人为源以外,周边区域传输也有较大影响.通过颗粒物污染的时间序列和空间插值的结合分析,可为进一步研究颗粒物时空关系及掌握区域污染特征提供方法.