The purpose of Phase II operations of the Interstate Air Pollution Study was stated in the Phase II Project Agreement: "The purpose of the project is to study in detail air The development of an effective air resource management program begins with identification of the pollutants in the air, and determination of the quantity and origin of each type. The air quality measurement program was designed and operated to make these determinations in the Metropolitan St. Louis area. Once the physical aspects of the air pollution problem are defined, air-pollution-effect data and criteria as well as opinion surveys can be used to set the air quality goals. From this base, with use of the pollutant emission inventory, the air resource management emission control plan can be designed. At this stage the air quality measurement program is used to monitor the air quality to assure that the goals are attained. In additon to its use in the air resource management program, this report provides a reasonably complete list of air quality data in a form that will assist research and program personnel in developing activities and attaining program objectives. Figure 1, a population distribution map of the Study area, is provided to allow comparison between distribution of population, pollutants, and sampling measurement networks. MEASUREMENT METHODS Essentially two types of pollutants occur in the air, particulates and gases. The particulates are classified as suspended and settleable. The suspended particulates vary in size from less than 1 to approximately 100 microns; they remain suspended in the atmosphere for long periods of time. Because the settleable particulates are 2 400000 410 420 430 440 450 460 470 480 490 500000 510 520 530 540 550 Figure 1. Population from 1960 census by 5, 000-foot grid squares. much larger and heavier, they settle out of the air relatively close to their source. The gaseous pollutants, which are molecular in size, remain mixed in the atmosphere indefinitely since they have approximately the same density as the air itself. Figures 2 and 3 are maps of the area showing the sampling site locations and delineating the equipment at each site. Table 1 gives a summary of all equipment and measurements made during the Study. Tables 2,3, and 4 give a classification of each site and the potential air pollution sources around them. Classifications are made using a modified Air Pollution Control Association (APCA) designation explained in Table 2. The classification describes three circular-segmented zones of activity around the station: 0 to mile, to mile, and to 1 mile. A single classification has not been assigned to a 360-degree circumference, but is given for 45-degree arcs centering in the north, in the northeast, and so on around the total circumference. This system records for eight directions from the samplers, the types of air pollutant source activity in operation. It helps with interpretation of data from each station. Albums of black and white photographs were compiled to show the sampling sites and equipment and a view from the site in each principal direction. These albums were given to the Illinois Department of Public Health, the St. Louis Division of Air Pollution Control, and the St. Louis County Health Department. Meteorological data are from the Weather Bureau Station at Lambert Field. Their relationship to data from other years and to the rest of the Study area is covered in Volume V, Meteorology and Topography. The stability classes were determined from meteorological data from Lambert Field by the Pasquill-Gifford-Turner stability classification criteria. These criteria are based on surface wind speed, daytime solar insolation, and nighttime cloud cover. They give the following classes: (1) extremely unstable, (2) unstable, (3) slightly unstable, (4) neutral, (5) slightly stable, (6) stable, and (7) extremely stable. For the purposes of this report, classes 6 and 7 are grouped with class 5. Thermal mixing, as influenced by solar radiation, is at its maximum for class 1 and at its minimum for class 5. The wind speed, however, is lowest at class 1, increases to its maximum at class 4, and decreases again at class 5. The size of the air quality measurements program and the variety of measurements made are a credit to the numerous cooperating organizations and individuals. PARTICULATE POLLUTANTS Suspended Particulates Suspended particulates were measured by both the high-volume air sampler and the AISI tape sampler. Suspended particulates are small particles that absorb, reflect, and scatter the sunlight and thus obscure visibility. When breathed, they |