Air Quality Modeling in the South Coast Air Basin of California: What Do the Numbers Really Mean?

Abstract

This study evaluates air quality model sensitivity to input and to model components. Simulations are performed using the California Institute of Technology (CIT) airshed model. Results show the impacts on ozone (O₃) concentration in the South Coast Air Basin (SCAB) of California because of changes in: (1) input data, including meteorological conditions (temperature, UV radiation, mixing height, and wind speed), boundary conditions, and initial conditions (ICs); and (2) model components, including advection solver and chemical mechanism. O₃ concentrations are strongly affected by meteorological conditions and, in particular, by temperature. ICs also affect O₃ concentrations, especially in the first 2 days of simulation. On the other hand, boundary conditions do not significantly affect the absolute peak O₃ concentration, although they do affect concentrations near the inflow boundaries. Moreover, predicted O₃ concentrations are impacted considerably by the chemical mechanism. In addition, dispersion of pollutants is affected by the advection routine used to calculate its transport. Comparison among CIT, California Photochemical Grid Model (CALGRID), and Urban Airshed Model air quality models suggests that differences in O₃ predictions are mainly caused by the different chemical mechanisms used. Additionally, advection solvers contribute to the differences observed among model predictions. Uncertainty in predicted peak O₃ concentration suggests that air quality evaluation should not be based solely on this single value but also on trends predicted by air quality models using a number of chemical mechanisms and with an advection solver that is mass conservative.     

Air Pollution Administrative Trends—the Canadian Scene

A re-organized local agency for the administration of an air pollution by-law in a group of adjoining municipalities now employs professional staff together with laboratories for air quality analyses, source testing, and applied research and new ideas in the development of improved fuel-burning and control equipment. The agency functions to prevent new sources of pollution, to disseminate information and advice and to provide leadership in the community. Its administrative activities include the use of consultants and outside research organizations for special problems and subjects of a political or controversial nature. However, to deal with the rare and complex contaminants which may be harmful to health now necessitates some assistance from the higher governments. The practices discussed have been employed for several years with general success in the Municipality, following closely the recommendations of a Select Committee of the Legislative Assembly of the Province which traveled and held hearings 1955 to 1957 in the major cities of the U.S.A. and Canada.     

Air Pollution Resulting from Incineration—its Reduction and Control

Historically, in evaluations of the impact of power plant emissions, the region of concern was generally the immediate vicinity (up to a radius of about 100 km) of the power plant in question, and the pollutant of concern was mainly sulfur dioxide emitted by the power plant. In most scientific work relating to atmospheric transport of emissions, little or no attention was given to the regional (up to a radius of about 1000 km) transport of pollutants. Recently, however, more emphasis has been placed on the evaluation of regional transport^1-8.     

Using Farmers’ Actions to Measure Crop Loss Due to Air Pollution

The effects of ozone on the profitability of Illinois cash grain farms is investigated by utilizing a profit function framework. This approach uses individual farms as the observational unit so the data are generated under field conditions. Hence, experimental plot data are not used although results from past biological experiments are utilized to frame initial hypotheses and for evaluation of the estimated model. This study demonstrates the benefits of combining economic data and biological science results to estimate the economic reactions of producers in terms of input and output (production) response to an ambient environmental characteristic.

A time series of cross sectional data on cash grain farms in Illinois is used to estimate two profit functions. Ozone data are measured on a growing season basis by county. The estimated model shows ozone has a negative effect on profits. Increases in ozone levels tend to depress output levels and lessen the demand for variable inputs. Additionally, a production function is derived from one of the profit functions. The impact of ozone is found to be in general agreement with dose-response data obtained in Illinois by plant scientists.     

Interstate Air Pollution Study—St. Louis Area Air Pollutant Emissions Related to Actual Land Use

The Interstate Air Pollution Study of the St. Louis-East St. Louis Metropolitan Area, conducted in 1963–1964, provided data for this report of air pollutant emissions related to three land-use categories: (1) residential, (2) institutional and commercial, and (3) industrial. A fourth land-use category, transportation and open space, is included in some calculations. The sources of pollutants considered are: (1) power generation, both electric utilities and industrial, (2) fuels used for space heating, (3) solid waste disposal, and (4) industrial processes. The pollutant emissions considered are particulates and sulfur oxides. Cumulative frequency distributions given are based on acres of land use and corresponding emissions per unit area. These frequency distributions—actual emission conditions that can be related to known air quality levels—provide a basis for performance standards and a guide for planners and others in future city developments, not only in St. Louis but in other similar cities as well. A suggested method for determining a different type performance zoning standard is presented. This standard is based on average conditions and thus would supplement, not replace, standards based on maximum allowable emissions. Calculations for such standards relating to St. Louis are presented.     

What Do the Occurrences of Migratory Fishes in the Upper Mekong Mean?

This paper examines the recent appearance of four migratory species in the Upper Mekong: Dasyatis laosensis, Anguilla bicolor, Anguilla marmorata, and Chitala ornata. Since 2006 these species have been continually sampled in an area below Jinghong Dam in Xishuangbanna, China. This region is far beyond their historical upstream distribution, and the reasons for these appearances and their subsequent impact on river ecosystem are considered.     

The State’s Role in the Development of Local Air Pollution Control Programs

This paper examines the history of air pollution control in the State of New Jersey, particularly, how it relates to the development of the state-local governmental relationship, and to the coordination of their respective control efforts. It also describes the methodology for developing local control programs. The information presented in the paper is directed to those individuals who may be able to analogize the experience in New Jersey to situations developing in their own jurisdictions.     

On the Determination of Odor Thresholds in Air Pollution Control—An Experimental Field Study on Flue Gases from Sulfate Cellulose Plants

From the hygienic point of view, not only the health hazards caused by air pollutants but also the odor from emitted flue gases should be reduced to a minimum. An effective control of the risk of odor at ground level presupposes knowledge of the source concentration of the odoriferous gas as well as its odor threshold. This threshold has to be estimated empirically, as the flue gases often contain a complex mixture of different odoriferous substances, the odor thresholds of which are in most cases unknown. For this purpose a method has been developed for estimating the odor thresholds of flue gases emitted, from different industrial processes. The method, afield method, is based on an exposure procedure, a number of subjects compare different concentrations of the flue gas with samples of fresh air and decide at what concentration the flue gas is no longer noticeable. The gas samples used are neither compressed, nor absorbed or heated before the exposure test. The method has been used in two studies on gases from Swedish sulfate cellulose plants. In order to estimate the effect on the odor threshold of different deodorizing measures, gas samples were taken not only from the stack but also from different phases in the production process. The results and a brief discussion on the practical applications of the method are given.     

Do international investment contribute to environmental pollution? Evidence from 20 African countries

Environmental Science and Pollution Research - International investment is needed in every economy, and every economy is expected to grow and attract investment. Despite the need of the above in...     

What have we learnt from the European Union's Emissions Trading System?

The EU Emissions Trading System (ETS) demonstrated the ability to design and launch a large-scale trading system in a short period of time. The path from initial reticence about emissions trading to implementation of the world's largest program is an important history. Three issues play a large role in the evaluation of the program to date and its on-going development: allocation plans, cost uncertainty, and leakage of emissions to abroad. Decisions in Phase I and II (2005-2012) were responsive to questions of political feasibility and implementation, but some of these decisions including allocation in particular will be substantially revised in Phase III (2013-2020).     

Do herbicide treatments reduce the sensitivity of mosquito larvae to insecticides?

Invasive mosquitoes are economic and sanitary concerns especially in Europe and America. Most work has emphasized the role of resistance [Berrada, S., Fournier, D., Cuany, A., Nguyen, T.X., 1994. Identification of resistance mechanisms in a selected laboratory strain of Cacopsylla pyri (Homoptera: Psyllidae): altered acetylcholinesterases and detoxifying oxidases. Pesticide Biochemistry and Physiology 48, 41-47; Hemingway, J., Hawkes, N.J., McCarroll, L., Ranson, H., 2004. The molecular basis of insecticide resistance in mosquitoes. Insect Biochemistry and Molecular Biology 34, 653-665] to insecticides. Compounds acting on larval sensitivity to insecticides are not well studied and their action remains poorly understood. Among several residual chemicals in ecosystems, particularly in wetlands, we identified a possible interaction of an herbicide on larval resistance to an insecticide. Our work contributes to the global control of mosquito populations by identifying possible pathways of resistance to insecticides of these vectors. Resistance or tolerance to insecticide treatments might contribute to successful invasion by mosquitoes. Here we report an ecotoxicological approach to test the hypothesis of an indirect effect of atrazine on mortality of an invasive vector. A brief contact (48h) between Aedes aegypti mosquito larvae and atrazine led to a modification of larval sensitivity to an insecticide: using atrazine as an inducer led to a decrease in the mortality of larvae treated with Bacillus thuringiensis var. israelensis (Bti).     

Air quality measurements—From rubber bands to tapping the rainbow

It is axiomatic that good measurements are integral to good public policy for environmental protection. The generalized term for “measurements” includes sampling and quantitation, data integrity, documentation, network design, sponsorship, operations, archiving, and accessing for applications. Each of these components has evolved and advanced over the last 200 years as knowledge of atmospheric chemistry and physics has matured. Air quality was first detected by what people could see and smell in contaminated air. Gaseous pollutants were found to react with certain materials or chemicals, changing the color of dissolved reagents such that their light absorption at selected wavelengths could be related to both the pollutant chemistry and its concentration. Airborne particles have challenged the development of a variety of sensory devices and laboratory assays for characterization of their enormous range of physical and chemical properties. Advanced electronics made possible the sampling, concentration, and detection of gases and particles, both in situ and in laboratory analysis of collected samples. Accurate and precise measurements by these methods have made possible advanced air quality management practices that led to decreasing concentrations over time. New technologies are leading to smaller and cheaper measurement systems that can further expand and enhance current air pollution monitoring networks.

Implications: Ambient air quality measurement systems have a large influence on air quality management by determining compliance, tracking trends, elucidating pollutant transport and transformation, and relating concentrations to adverse effects. These systems consist of more than just instrumentation, and involve extensive support efforts for siting, maintenance, calibration, auditing, data validation, data management and access, and data interpretation. These requirements have largely been attained for criteria pollutants regulated by National Ambient Air Quality Standards, but they are rarely attained for nonroutine measurements and research studies.