Lead as a tracer for automotive particulates: projecting the sulfate air quality impact of oxidation catalyst-equipped cars in Los Angeles

An analysis of the fate of lead in the Los Angeles Basin is used to evaluate an emissions to air quality model for automotive exhaust particulates. The dispersion model is then applied to projecting the annual average sulfate air quality impact of direct sulfuric acid mist emissions from oxidation catalyst-equipped cars of the 1975 model type. Estimates are given of the incremental sulfate contributions from three model years of oxidation catalyst-equipped cars burning a relatively low sulfur gasoline, and from roughly ten model years of 1975-type autos burning gasoline of sulfur content equal to that of the entire 1974 Southern California gasoline pool. In the latter case, sulfate concentrations in portions of downtown Los Angeles in 1985 could be elevated by roughly two thirds above present average sulfate values

Cost and Performance of Automotive Emission Control Technologies

The problem at hand is to investigate the near-term commercial feasibility of a wide range of automotive emission control technologies. The central issues can best be explained in terms of the emission control characteristics of each technology and their costs. Governmentally established emission control standards may be viewed as constraints on the use of a given vehicle and engine design. Either the technology meets the standard in use or it will not be sold. Emission control technologies that show promise of near-term manufacturability will be identified. Then, without presuming what future emission standards will be, the emission characteristics of example vehicle-engine combinations will be listed. Technologies that are acceptable, given a specified emission standard, can then be identified by a process of elimination. The approach to identifying the relevant costs associated with a given technology is not as clear cut. One would like to think that the most basic question governing the adoption of a given feasible technology is, "Will it be purchased by the public?" The second part of this paper will discuss the impact of pollution control technology on the economic decisions facing the new car customer. The cost considered by the rational new car consumer involves more than first cost. Other important factors include maintenance, operating expenses, resale value, and financing charges. Since resale value and financing charges are highly time dependent, it is possible that a new car purchaser's decision on which technology to buy may depend on how long he plans to keep the car. A cost annualization procedure will thus be developed which considers these factors

The design of efficient air pollution control strategies

This statement addresses gains in economic efficiency which could be obtained by removing barriers to advances in the technology and procedures commonly used for designing air pollution abatement strategies

Dimensions of the Los Angeles SO_2/sulfate problem

Sulfur dioxide emission trends are reviewed in relation to sulfur dioxide air quality in the Los Angeles area. Emission fluctuations over the 19-year period from 1956 through 1974 are explained in terms of emission control policy changes. Simple statistical tests indicate that measured SO_2 air quality levels at Long Beach and downtown Los Angeles track changes in emission strength at nearby sources and from sources with low effective stack height. Atmospheric oxidation of SO_2 to form particulate sulfates is discussed. Sulfate air quality measurements at Los Angeles show a broad summer seasonal peak in all years of record, with isolated periods of very high sulfate concentration in some winters of record. The geographic distribution of long term average sulfate concentrations is examined and found to be rather uniform across existing monitoring stations in the Los Angeles Basin. Fluctuations in measured sulfate values from day to day are shown to track changes in inversion height, relative humidity, total suspended particulate levels, and ozone concentrations. From these relationships, it is suggested that day-to-day fluctuations in sulfate concentration are driven mainly by changes in SO_2 to sulfate reaction rate and by changes in the effective mixing volume of the air basin

The relationship between sulfate air quality and visibility at Los Angeles

Routine air monitoring data taken by the Los Angeles Air Pollution Control District are related to visibility at downtown Los Angeles over the decade 1965 through 1974. The relationship between light extinction and total suspended particulate mass implied by the historical data base is shown to be consistent with the findings of previous short-term studies. A non-linear regression model for light extinction at Los Angeles is constructed which combines available information on aerosol chemical composition with relative humidity and NO_2 data. It is shown that there is a pronounced increase in light scattering per unit sulfate solute mass on days of high relative humidity, as would be expected for a hygroscopic or deliquescent substance. Using the chemically resolved regression model, estimates are made of the long-run visibility impact of reducing sulfates to one half and to one quarter of their measured historic values on each past day of record. It is found that the effect of such a sulfate concentration reduction would have been manifested most clearly in a decline in the number of days per year with average visibility less than three miles. The number of days per year with average visibility less than ten miles would be little affected. One reason for the disproportionate impact of sulfates on the days of the worst visibility is found in the high positive correlation between sulfate mass concentration and relative humidity. High values of light scattering per unit sulfate mass thus occur on days of high sulfate mass concentration

Mathematical modeling of chemically reactive pollutants in indoor air

A general mathematical model is presented for predicting the concentrations of chemically reactive compounds in indoor air. The model accounts for the effects of ventilation, filtration, heterogeneous removal, direct emission, and photolytic and thermal chemical reactions. The model is applied to the induction of photochemically reactive pollutants into a museum gallery, and the predicted NO, NO_x-NO, and O_3 concentrations are compared to measured data. The model predicts substantial production of several species due to chemical reaction, including HNO_2, HNO_3, NO_3, and N_2O_5. Circumstances in which homogeneous chemistry may assume particular importance are identified and include buildings with glass walls, indoor combustion sources, and direct emission of olefins

Emissions and air quality relationships for atmospheric trace metals

Atmospheric particulate matter samples taken in urban and rural locations can be analyzed routinely for more than forty trace elements. With the increasing use of automated X-ray fluorescence and neutron activation analyses (Dzubay, 1977; Cooper, 1973), the cost of trace metals determination in airborne particulate samples has been greatly reduced. As a result, large volumes of data are being acquired that contain considerable chemical resolution, including concentration data on toxic trace elements like lead, arsenic, cadmium and nickel

Modeling the Concentrations of Gas-Phase Toxic Organic Air Pollutants: Direct Emissions and Atmospheric Formation

An Eulerian photochemical air quality model is described for the prediction of the atmospheric transport and chemical reactions of gas-phase toxic organic air pollutants. Model performance was examined in the Los Angeles, CA, area over the period August 27-28, 1987. The organic compounds were drawn from a list of 189 species selected for control as hazardous air pollutants in the Clean Air Act amendments of 1990. The species considered include benzene, various alkylbenzenes, phenol, cresols, 1,3- butadiene, acrolein, formaldehyde, acetaldehyde, and perchloroethylene among others. It is found that photochemical generation contributes significantly to form-aldehyde, acetaldehyde, acetone, and acrolein concentrations for the 2-day period studied. Phenol concentrations are dominated by direct emissions, despite the existence of a pathway for atmospheric formation from benzene oxidation. The finding that photochemical production can be a major contributor to the total concentrations of some toxic organic species implies that control programs for those species must consider more than just direct emissions