podasbanld aie sealantels a dintWe hen cateeS te we Mob dh tn oat TE al aE Cie alae me 134 in the U.S.A. (and perhaps the entire world) to deliberately vary the rate of production of an atmospheric pollutant (sulfur dioxide) on a city-wide basis on a schedule designed to tell more about diffusion and transport over a large urban area. The incident control test discussed in this report represents a joint effort conducted by the Chicago De- partment of Air Pollution Control, the Atomic Energy Commission, and the National Air Pollution Control Administration of the Department of Health, Education and Welfare. entists in their efforts to develop a mathematical model to forecast air pollution levels (specifically, SO. eoncentrations) in Chicago from meteorological and emission data. Input data for this mode! include existing hourly air quality (SO2 concentrations), wind speed, and winddirection at each of the eight TAM (Telemetered Air Monitoring) stations in Chicago, standard hourly weather data at five additional locations, hourly SOs emission data from as Many 4S pos- sible of the large industrial, commercial and residen- tial point sources, and estimated hourly emissions personnel were to contact each plant, secure their co- from area sources due to space heating and small industrial sources. This computer model, if able to predict future SO: levels accurately, will be used to develop effective abatement procedures at minimal costs with details of the test schedule, objectives, etc. pollution incident occurs or is forecast. The Chicago Department of Air Pollution Control was responsible for program direction and for handling the mechanics of the fuel-switch test. DAPC operation and provide the appropriate plant officials DAPCalso provided the necessary forms for logging fuel consumption data. A total of 76 plants, which produce on an annual basis 85% of the city’s SOs, were asked to participate; forty-nine plants did. Scientists from the Reactor Engineering and Radiological Physics Divisions of Argonne cooperated with DAPCin the planning phases of this simulated “pollution incident control test.” Except for the starting date, the sehedule which resulted was about as close to a controlled laboratory experiment as one could hope to conduct in an area as large and diversified as the City of Chicago. This city-wide pollution experiment had three pri- mary objectives: (1) to act as a trial run for estab- lishing procedures for implementing effective SOs abatement procedures during a forecast period of air pollution buildup, (2) to observe changes in air quality due to fuel changes and to compare these changes with those computed from the diffusion equations, and (3) to provide Argonne scientists with detailed air quality, meteorological, and SO, emission data during a short period to aid in the development of better methods for predicting air pollution levels. This city-wide experiment did bring into sharper focus the practical actions that industry can and can- not realistically take to reduce or curtail SO» output during pollution episodes. Any air pollution abatement strategy must, of course, be based on accurate assessments of the availability of low sulfur fuels and industrial-commercial operating procedures, so that no undue burden will be placed on industry byair pollution control operations. Communications channels between DAPC and the operating engineers of the vari- ous plants were established and used; the test showed that improvements are needed. The third objective of the test was to provide the air quality and emission data needed by Argonnesel- and minimal disruption to industry whenever an air There is only one way to reduce air pollution levels during a period of poor ventilation conditions: reduce the rate of emission of the pollutants. In Chicago, sulfur dioxide is a major pollutant (but not the only one}. One could turn off SO, sources during an air pollution episode, but this would be economically and politically difficult. Or, the sources could convert to low sulfur fuels durmg the episode. In Chicago, an optimal abatement strategy for SOs basically consists of determining the best use of the available supply of natural gas and other low-sulfur fuels. The procedures used during the Summer 1968 fuel- switch test were as follows: Those industries with single-fuel capacity (coal or oil) were asked to collect and submit to DAPC detailed hourly fuel and sulfur consumption data for the entire test period, 16 June through 6 July 1968. Plants with dual-fuel capacity were also asked to maintain hourly fuel use records for the same period; they were further requested to burn their usual fuel for that season during the first week of the test, and to convert to maximum use of high-sulfur fuel between 0700 and 1100 CST on both June 24th and July Ist, 1968. During the week of June 23rd, Commonwealth Edison was asked to con- vert its plants to minimum use of high-sulfur fuels after 24, 48, or 72 hours on coal, with industry converting 1 day later; the exact date was determined by the weather forecast. It was hoped that fairly steady weather conditions would prevail for 48 hr or more after the 24th so that the SO. concentrations observed at each of the eight TAMstations could be compared with consecutive periods of similar weather but different SOs emission patterns. These conditions did not occur during the first week of the test, and little useful air quality data was obtained. Again on the morning of July Ist, all plants with dual-fuel capacity were