A New Approach to Roof Monitor Particulate Sampling

A new method for sampling of emissions from building monitors using high volume samplers while continuously recording the exit gas velocity is presented. A technique is also outlined for automatic isokinetic sampling using a high volume sampler.     

A Comparative Study of Aluminum Smelter Roof Vent Sampling Methods

Abstract

The purpose of the study was to quantify the impact of traffic conditions, such as free flow and congestion, on local air quality. The Borman Expressway (I-80/94) in Northwest Indiana is considered a test bed for this research because of the high volume of class 9 truck traffic traveling on it, as well as the existing and continuing installation of the Intelligent Transportation System (ITS) to improve traffic management along the highway stretch. An empirical traffic air quality (TAQ) model was developed to estimate the fine particulate matter (PM_2.5) emission factors (grams per kilometer) based solely on the measured traffic parameters, namely, average speed, average acceleration, and class 9 truck density. The TAQ model has shown better predictions that matched the measured emission factor values more than the U.S. Environmental Protection Agency (EPA)-PART5 model. During congestion (defined as flow-speeds <50 km/hr [30 mi/hr]), the TAQ model, on average, overpredicted the measured values only by a factor of 1.2, in comparison to a fourfold underprediction using the EPA-PART5 model. On the other hand, during free flow (defined as flow-speeds >80 km/hr [50 mi/hr]), the TAQ model was conservative in that it overpredicted the measured values by 1.5-fold.     

Evaluation of Absorption Sampling Devices

The information presented in this paper is directed to those with the responsibility of designing and operating air quality monitoring networks. An analytical model for location of monitor sites based upon maximizing a sum of coverage factors for each source is developed. An heuristic solution method from the facilities location analysis literature is used for solution of the model. Results of an example problem are presented and compared with the monitoring network currently In place. The model is shown to be a valuable addition to the methods available to the air quality monitor network designer. Needs for further research are pointed out.     

Selection of Adhesive-Coated Materials for Particulate Sampling

The use of adhesive surfaces for the collection and evaluation of airborne particulates, including radioactive dusts and aeroallergens, is steadily increasing. Although many types of adhesives and adhesive-coated materials are commercially available, very few are suitable for continuous monitoring applications. Late in 1 964, the Cincinnati Division of Air Pollution Control received a U. S. Public Health Service, Division of Air Pollution, Research Grant for the refinement and standardization of a method of particulate sampling utilizing adhesive surfaces as collection media. One of the first phases of this project was to select the adhesive-coated material best suited for the method. The research which led to this selection, from a group of 37 different materials, is reported.     

A Comparative Study of Environmental Tobacco Smoke Particulate Mass Measurements in an Environmental Chamber

Particulate mass concentration measurements have been made on environmental tobacco smoke (ETS) for the purpose of assessing the relative accuracy of several measurement procedures. ETS over a range of concentrations was generated in an environmental chamber by three methods. Mass concentration was measured by a gravimetric/spectrophotometric collection procedure, piezoelectric particle mass monitors, two nephelometry-based mass monitors, and a particle counting and sizing system. Two-hour average mass concentrations were determined by each method for concentrations ranging from very low levels up to those achieved by smoking one entire cigarette in the chamber. Statistical comparisons were made among procedures employing the gravimetric filter measurement as the basis for comparison. One nephelometry-based procedure gave significantly higher and the other significantly lower values than the filter determination. In one case, a correction for the difference between the particle mass density of the calibrating aerosol and that of ETS brought the nephelometry-based procedure into reasonable agreement with the filter measurement, while for the other, the correction did not resolve the discrepancy between methods. Statistically significant differences between the responses of two supposedly identical piezoelectric mass monitors were found, as was some slight dependence of the nephelometry- based procedures on method of ETS generation. In summary, the results indicate that significant errors can be expected if the instruments studied are used “off the shelf,” even for ETS generated under controlled laboratory conditions. Caution should be employed in field measurements where numerous sources and types of particulate matter can be encountered.     

Particulate and Nicotine Sampling in Public Facilities and Offices

Abstract

The purpose of this study was to characterize and measure indoor air quality in public facilities and office buildings. The pollutants of interest were particulate matter smaller than 2.5 μm in diameter, PM-2.5, and environmental tobacco smoke (ETS). Integrated PM- 2.5 samples were taken on Teflon membrane filters using Harvard Aerosol Impactors as a pre-size selector. Filters were analyzed by gravimetric analysis. Nicotine, which was used as a marker for ETS, was collected on sodium-bisulfate-impregnated, glass-fiber filters and was analyzed by gas chromatography. Twenty-one structures were monitored in Metropolitan Boston. Measured particle concentrations ranged from 6.0 μg/m³ to about 550 μg/m³. Nicotine concentrations were as high as 26 μg/m³ in a designated smoking room. Real-time measurements were also taken using two types of nephelometers; a Handheld Aerosol Monitor (HAM) and a Miniature Real-Time Aerosol Monitor (MINIRAM). Short-term field measurements with these instruments correlated better with the integrated PM-2.5 concentrations in smoking locations than with concentrations in non-smoking areas.     

A Pilot Indoor-Outdoor Study of Organic Particulate Matter and Particulate Mutagenicity

Abstract

Many large metropolitan areas experience elevated concentrations of ground-level ozone pollution during the summertime “smog season”. Local environmental or health agencies often need to make daily air pollution forecasts for public advisories and for input into decisions regarding abatement measures and air quality management. Such forecasts are usually based on statistical relationships between weather conditions and ambient air pollution concentrations. Multivariate linear regression models have been widely used for this purpose, and well-specified regressions can provide reasonable results. However, pollution-weather relationships are typically complex and nonlinear—especially for ozone—properties that might be better captured by neural networks. This study investigates the potential for using neural networks to forecast ozone pollution, as compared to traditional regression models. Multiple regression models and neural networks are examined for a range of cities under different climate and ozone regimes, enabling a comparative study of the two approaches. Model comparison statistics indicate that neural network techniques are somewhat (but not dramatically) better than regression models for daily ozone prediction, and that all types of models are sensitive to different weather-ozone regimes and the role of persistence in aiding predictions.     

A Study of Wood Stove Particulate Emissions

Particulate emission factors for two wood stove models have been determined for two types of fuel and a range of operating conditions. The emission factors range from 1 g/kg (fuel) to 24 g/kg. A model is presented which represents the emission factor as a simple function of the ratio of fuel load to combustion rate, or the length of time between refueling. This model is felt to be appropriate for evaluating the impact of wood-based residential space heating on ambient air concentrations of particulate matter If certain assumptions can be made about stove operating conditions. An application of the emission factor model to a typical community suggests that the contribution of wood stoves to ambient particulate levels might reach 100 μg/m³ if the entire heating load were carried by wood.

Preliminary analyses of the particulate matter Indicate that benzene extractables range from 42% of the total particulate mass at short refuel times to 67% at longer refuel times. About 45% of the mass of benzene extractables appeared in the neutral fraction of acid base extractions. Polycyclic aromatic hydrocarbons are expected to be included in this neutral fraction.     

Theoretical Limits of Errors Due to Anisokinetic Sampling of Particulate Matter

Theoretical estimates of errors in calculated concentrations of particulate matter, sampled with aspirated nozzles under conditions of anisokinetic flow, were based on computed trajectories of particles in fluid streams. In the trajectory determinations gravitational effects on the particles were neglected and the fluid flow patterns approximated by those of a frictionless ideal fluid. The equations of motion were derived considering inertia as the predominant mechanism in the collection of the particulate matter by an aspirated nozzle. The particles were assumed to be spherical in shape, monodisperse, and experiencing drag force as in a real fluid. The equations of motion were solved by a procedure combining an analog and a digital computer. The theoretical error estimates for anisokinetic sampling were compared with experimental data available on investigations with spherical test dust.     

High-Volume Sampling: Effect of Windborne Particulate Matter Deposited during Idle Periods

For high volume air sampling, New York State uses a random once every six days schedule. To avoid double travel, this usually requires leaving filters mounted for five days before the actual sampling period of 24 hr. The starting and stopping of the sampling is controlled by a 7 day timer. (At the maximum, it is possible that a filter could be in place for 10 days with the motor idle.) The purpose of this investigation was to determine whether the filter collects a significant weight of particulate matter during the period the motor is idle, and what effect the collected windborne particulate matter has on computed TSP concentrations.     

汽车尾气颗粒物对动物肺泡巨噬细胞的免疫毒性及比较

研究汽车尾气颗粒物气管染毒后对大鼠肺泡巨噬细胞免疫功能的影响，结果是动物肺泡巨噬细胞Ｆｃ受体表达、ＡＭ抗肿瘤细胞毒作用、抗体介导细胞毒作用受到抑制，具有明显的剂量效应关系；总体比较，汽油车尾气颗粒物对ＡＭ免疫功能影响较柴油车严重。     

Development of a High Purity Filter for High Temperature Particulate Sampling and Analysis

This paper is directed to those interested in measuring trace metals in high-temperature particulate emissions. Particulate handsheet filters with satisfactory purity, efficiency, thermal stability, cost, strength (about 1 lb/in.), and flexibility for analysis of particulates in gases up to 800°C have been made with 99.2% Si0₂ Microquartzfibers. Almost all purity requirements for optimum atomic absorption and flame emission spectrophotometric analysis for trace metals have been achieved. The filters appear highly promising for X-ray fluorescence analysis but should be further evaluated. Suitability of the filters for neutron activation analysis is uncertain and should also be further evaluated. Dioctyl phthal-ate (DOP) aerosol efficiencies of 99 to 99.99% have been achieved by using fibers of various diameters. The filters are insensitive to humidity, insoluble In most acids and organic solvents. The handsheet filters have a slightly alkaline pH, but similar filters have been made on a papermaking machine with a pH of 6.4. Cost is estimated to be about $2.00/ft².     

A Preliminary Study of Particulate Emissions from Small Wood Stoves

This paper summarizes the methodology developed to analyze alternative oxidant control strategies of the 1979 Air Quality Plan for the San Francisco Bay Area. The analysis of alternative oxidant control strategies is a complex task, particularly when a grid-based photochemical model is the primary analysis tool. To handle quantitatively spatial and temporal variations in emissions under both existing and projected future conditions, as well as to simulate the effects of a wide variety of control strategies, a system of computer-based models was assembled. The models projected and distributed a number of variables in space and time: population, employment, housing, land use, transportation, emissions, and air quality. Given time and budget constraints, an approach to maximizing the information return from a limited number of model runs was developed. The system was applied in three sequences to determine (1) what future air quality would be if no further controls were implemented, (2) the degree of hydrocarbon and NO_x emission control necessary to attain the oxidant standard, and (3) the effectiveness of alternative stationary source, mobile source, transportation and land use control strategies in contributing to attainment and maintenance of the oxidant standard.

A number of significant modeling assumptions had to be developed in order properly to interpret the modeled results in the context of the oxidant standard. In particular, a Larsen-type analysis was used to relate modeled atmospheric conditions to “worst case” conditions, and a proportional assumption was made to compensate model results for an imperfect validation. The specification of initial and boundary conditions for future year simulations was found to be a problem in need of further research.     

The Precision Associated with the Sampling Frequencies of Total Particulate at Indianapolis,Indiana

The frequency distribution of total suspended particulate matter for Indianapolis, Ind., was examined in order to determine the precision associated with any given sampling scheme. By assuming a basic log_e-normal distribution, a theoretical set of confidence intervals about the geometric mean was derived for random sampling. Verification of the log_e-normal distribution was made for particulate matter in Indianapolis. Application of the derived confidence intervals revealed that for a 30-day period 20 samples must be taken to ensure that the 90% confidence interval will be within 10% of the geometric mean. Analysis of the records for 19 sampling locations within Indianapolis revealed that only 2 sites possessed sufficient data to allow monthly climatological evaluation over the period 1968-1970.     

Metallic Element Composition of Particulate Matter During Day and Night Sampling at a Traffic Site

Day and night period sampling programs were carried out using a versatile air pollutant system to collect fine particulate matter (PM_2.5) and coarse particulate matter (PM_2.5–10) simultaneously at a traffic junction that is only 60 m from HungKuang University located in Central Taiwan. Therefore, HungKuang University is regarded as the traffic sampling site in this study. Similar measurements were carried out in a previous 2013 study by Fang and colleagues during October 2012 to November 2012. Determination of metallic element composition of fine and coarse particulates collected during the day and the night was accomplished with inductively coupled plasma atomic emission spectrometry (ICP-AES). The results indicated that there were no significant differences in composition of metallic elements Zn, Cu, Cr, Mn, Fe, Pb, and Cd in either coarse or fine particles for both day and night sampling periods. The statistical results indicated no significant differences for metallic elements in the PM_2.5–10 particulates for day and night sampling periods. Also, no significant differences were noted for metallic elements in the PM_2.5 particulates for day and night sampling periods at this traffic sampling site. The proposed reason is the limited sampling period employed in this study. Another potential reason is the presence of traffic that runs heavily both day and night being a major contributor to the ambient air metallic pollutants in this region.     

Determination of Fine Particulate Semi-Volatile Organic Material at Three Eastern U.S. Sampling Sites

ABSTRACT

Correct assessment of fine particulate carbonaceous material as a function of particle size is, in part, dependent on the determination of semi-volatile compounds, which can be lost from particles during sampling. This study gives results obtained for the collection of fine particulate carbonaceous material at three eastern U.S. sampling sites [Philadelphia, PA; Shenandoah National Park, VA; and Research Triangle Park (RTP), NC] using diffusion denuder technology. The diffusion denuder samplers allow for the determination of fine particulate organic material with no artifacts, due to the loss of semi-volatile organic particulate compounds, or collection of gas-phase organic compounds by the quartz filter during sampling. The results show that an average of 41, 43, and 59% of fine particulate organic material was lost as volatilized semi-volatile organic material during collection of particles on a filter at Philadelphia, RTP, and Shenandoah, respectively. The particle size distribution of carbonaceous material retained by a filter and lost from a filter during sampling was obtained for the samples collected at Philadelphia and Shenandoah. The carbonaceous material retained by the particles during sampling was found predominantly in particles smaller than 0.4 μm in aerodynamic diameter. In contrast, the semi-volatile organic material lost from the particles during sampling had a mass median diameter of ~0.5 μm.