(1989). Time-resolved Identification and Measurement of Indoor Air Pollutants by Spectroscopic Techniques: Gaseous Nitrous Acid, Methanol, Formaldehyde and Formic Acid. JAPCA: Vol. 39, No. 10, pp. 1344-1347.
Hazardous waste minimization is becoming increasingly important as the United States struggles to safely treat and dispose of existing wastes. The extent to which hazardous wastes will be minimized—in either volume and/or toxicity—in the production process depends largely upon the response of industrial waste generators. A survey of large Tennessee waste generators was carried out in the summer of 1987. It found that industry has begun to implement a number of waste minimization practices and that the overall attitude of generators toward waste minimization was positive. There were some statistically significant differences in the survey responses from generators of differing volumes. These differences are important and indicate that among large waste generators, the larger have taken more significant steps to date than have smaller waste generators.
Indoor and outdoor ozone concentrations were measured from late May through October at three office buildings with very different ventilation rates. The indoor values closely tracked the outdoor values, and, depending on the ventilation rate, were 20 to 80 percent of those outdoors. The indoor/outdoor data are adequately described with a mass balance model. The model can also be coupled with reported air exchange rates to estimate indoor/outdoor ratios for other structures. The results from this and previous studies indicate that indoor concentrations are frequently a significant fraction of outdoor values. These observations, and the fact that most people spend greater than 90 percent of their time indoors, indicate that indoor ozone exposure (concentration X time) is greater than outdoor exposure for many people. Relatively inexpensive strategies exist to reduce indoor ozone levels, and these could be implemented to reduce the public's total ozone exposure.
Congress has given the United States Environmental Protection Agency (EPA) a mandate to regulate the disposal of the Nation’s industrial and hazardous wastes. With the recent landfill prohibitions, or "land ban," many of the past practices for disposing of these wastes are no longer available. Incineration has been suggested as a probable alternative path to permanent disposal of many of these troublesome hazardous wastes. To make the decisions regarding whether incineration is a proper waste treatment or disposal option, incinerator testing is needed to investigate the ramifications of thermal destruction.
Air quality standards are established to prevent or minimize the risk of adverse effects from air pollution to human health, vegetation, and materials. In order to develop standards which provide an adequate measure of protection to vegetation, it is necessary to define, in as precise terms as possible, the relationship between ambient air quality and the potential for adverse effects on vegetation. Based on recent evidence published in the literature, as well as retrospective studies using data from the National Crop Loss Assessment Network (NCLAN), cumulative indices can be used to describe exposures of ozone for predicting agricultural crop effects. However, the mathematical form of the standard that may be proposed to protect crops does not necessarily have to be of the same form as that used in the statistical or process oriented mathematical models that relate ambient ozone exposures with vegetation effects. This paper discusses the limitations associated with applying a simple statistic that may take the place of a more biologically meaningful exposure parameter. While the NCLAN data have been helpful in identifying indices that may be appropriate for establishing exposure-response relationships, the limitations associated with the NCLAN protocol need to be considered when attempting to apply these relationships in the establishment of a secondary national ambient air quality standard. The Weibull model derived from NCLAN experiments must demonstrate its generality and universal applicability. Furthermore, its predictive power must be tested using independent sets of field data.
Extensive data on residential indoor and outdoor NO2 levels have been collected in a limited number of U.S. locations. To date, researchers have analyzed these data sets individually, but have not analyzed them in the aggregate. Results have not, therefore, been suitable for application in a nationwide exposure assessment. This paper presents an analysis of indoor and outdoor NO2 field measurements from five U.S. metropolitan areas for homes with gas-fueled ranges and discusses potential applications of the results. Using linear regression analysis, the relationship between indoor NO2 and various predictor variables was explored. Results indicated that ambient NO2 levels alone explain an estimated 37 percent of the variability in indoor NO2 levels, that the relationship between indoor and outdoor NO2 concentrations differs significantly from summer to winter months, and that homes with range pilot lights have indoor levels approximately 7 ppb greater than homes without pilot lights. A logistic regression model which predicts the distribution of indoor NO2 levels based on ambient NO2 concentrations was developed. Estimation and testing of the logistic model indicated good model performance. The model is particularly useful for addressing policy-oriented questions that involve the concept of "acceptable" threshold levels for human exposure to NO2.
Data from the literature on deposition of SO2 to various common materials in outdoor atmospheres are reviewed and presented in the context of a theoretical model. The model postulates two resistances to deposition: the aerodynamic resistance, controlled by atmospheric properties; and the surface resistance, controlled by the chemistry of the surface and its moisture layer. Since the dissolution of SO2 is sensitive to pH, buffering of the moisture layer by corrosion products is essential for SO2 deposition to continue. Thus, it is hypothesized that SO2 deposits preferentially on those surfaces that are sensitive to SO2 attack. Based on extant data, estimates of aerodynamic and surface resistances are derived from the literature and maximum dry deposition rates for SO2 are estimated. Such information could be used to formulate SO2 dose-response or damage functions for certain materials, based on short-term laboratory tests.
First-time measurements of the potentially toxic inorganic species of arsenic (arsenite and arsenate) have been obtained in fine (less than 2.5 microns AD) and coarse (greater than 2.5 microns AD) atmospheric particles in the Los Angeles area. A recently developed method that includes procedures for sample collection, preparation, and analysis was used in this study. Size-fractionated aerosol samples were collected with a high-volume dichotomous virtual impactor that employed polytetrafluoroethylene filters. Results were obtained for the recovery of arsenic standards added to unexposed and collected filters. Data from this study, indicated that the recently developed speciation method can be used to determine concentrations of As(III) and As(V) in atmospheric particulate matter samples. Size-fractionated aerosol samples were collected in the city of Industry during January and February 1987. In most samples, As(III) and As(V) were above the detection limit (approximately 1 ng m-3 of either species) in both aerosol size fractions. A greater portion (about 75 percent) of the two species were observed in the fine particles. The As(III)/As(V) ratio for both particle sizes was close to 1 (i.e., an equal mixture of both species). Comparison of total suspended particulate arsenic measured by the speciation method to that measured by a routine California Air Resources Board-approved procedure showed good agreement (r = 0.94), indicating both methods were approximately equivalent for the collection and analysis of aerosol arsenic.
A method for the high resolution, high sensitivity analysis of polluted air for individual organic compounds is described. Samples collected from 50 mL of ambient air at 87 K (liquid argon) are injected without use of a valve into a silica capillary column which is then temperature programmed from -30 degrees C to 180 degrees C. Hydrocarbons (4 to 10 carbons) as well as carbonyl compounds, chlorinated compounds and terpenes can be identified and quantified. The detection limit, not strongly dependent on carbon number, is estimated to be 0.3 ppbc in a 50 mL sample. Use of small samples eliminates the need to remove water vapor, a procedure which might jeopardize sample integrity.
A mathematical model has been developed to study the thermal and chemical processes occurring In a municipal solid waste mass combustor. Treating the solids feed as a mixture of pseudo-components, the model determines the Interrelationships between the solids feed rate, grate travel rate and length, amounts and distributions of primary and secondary air, extent of solids burn out, and the bed and flame temperatures. The model Incorporates the kinetics of pyrolysis of solids and simulates heat and mass transfer within the bed. The temperature and mass flow profiles generated show that much of the grate Is taken up by the heatup and burnout zones. The heatup zone can be reduced by distributing the primary air to maintain minimal air flow In that region, thereby permitting rapid heatup. Increasing the solids feed rate and adjusting the air flow distributions can reduce the length of the burnout zone. The computer program, available on both PCs and mainframe, can be used for different MSW Incinerator dimensions and feed parameters to Investigate the effects of the control variables and optimize the desired output characteristics, e.g., maximize solids throughput.
An artifact in the use of grab sampling techniques for the measurement of N2O emissions from fossil fuel combustion has been identified. Storing combustion products containing SO2, NOX and water for periods as short as two hours can lead to the formation of several hundred parts per million of N2O where none originally existed. The amount of N2O formed depends both on the amount of NOX and SO2 originally in the container. The experimental results are supported by a proposed chemical mechanism and kinetic calculations. An investigation of sampling protocols indicate that drying the gas to a 0°C dewpoint before introduction in the container reduces, but does not eliminate, N2O formation. More complete drying may yield a valid sample although this approach has, as yet, not been evaluated. Valid grab samples can be obtained by either 1) removing the SO2 before introducing the gas into the container; or 2) increasing the pH of the aqueous phase in the container with NaOH. The findings of this work have important consequences with respect to the role of combustion generated N2O in the atmospheric N2O balance, since much of the present data base has been obtained using grab sampling techniques.
Under the SITE Emerging Technology Program, the U.S. Environmental Protection Agency is seeking to foster the further development of technologies that have been successfully tested at bench-scale and are now ready for pilot-scale testing, prior to field- or full-scale demonstration. The goal is to ensure that a steady stream of permanent, cost-effective, technologies will be ready for demonstration in the field, thereby increasing the number of viable alternatives available for use in Superfund removal and remedial actions. Under this program, EPA can offer technology developers financial assistance of up to $150,000 per year, for up to two years. The program is in its second year with seven projects underway and eight more ready to start, pending completion of award actions. The Third Emerging Technology Program Solicitation is open to the receipt of new proposals from July 8,1989 through September 7,1989. The purpose of this article is to provide the reader with: (1) an introduction to the Emerging Technology Program; (2) an understanding of how the Program operates; (3) a summary of those technologies currently being tested and evaluated under the Program; and (4) information on how to apply to the Program.
Two recent power plant plume studies by mobile, ground-based and airborne lidar have recorded cross-section images of plumes with sharply-defined layered and connected bands of aerosol in the vertical. Of the external parameters considered, wind direction and speed changes in the vertical were found to be associated most with these plume types. Statistical analyses indicate that both direction and speed shear are highly correlated with the layered plumes.
The A&WMA Critical Review entitled "Health Effects of Ozone" was presented by Morton Lippmann, Deputy Director of the Institute of Environmental Medicine at New York University Medical Center. Dr. Lippmann presented his review at the 82nd Air & Waste Management Association Annual Meeting and Exhibition, held in Anaheim, California in June 1989. The Critical Review paper, published in the May 1989 issue of JAPCA, provides a detailed evaluation of the available exposure, epidemiological, physiological and cellular data concerning the health effects of ozone on man and laboratory animals. Prepared discussions presented during the Critical Review session in Anaheim are published here, along with some closing remarks by Dr. Lippmann. Ronald Harkov, Chairman of the Critical Review Subcommittee of the Publications Committee, served as moderator of the 1989 A&WMA Critical Review session.
