Document jmK1q8wEqqnykLqqJXXG6LQa5

i .i :<, > C* * i t Jv t- p ft: T .1 .V'. , li-v : I !. i -ij 400 INDUSTRIAL HYGIENE AND OCCUPATIONAL MEDICINE THE METHOD The city in question is typical of many river valley cities in the United States. It has a population of some 40,000; it has a few large industrial plants and a large railroad yard, and about one half of the surveyed adults were employed in the plants or the yard. Bituminous coal is the fuel commonly in use. In the selection of a relatively low pollution area and a relatively high pollution area for the house to house collection of morbidity data, we studied the data that had been accumulated for sorne years by the dubious method of dust pots placed throughout the city. While recognizing the: uncertainties involved in using this method as an indicator of air pollution, we wish to emphasize that quantitative readings for the collected dust in the various pots had a wide range by location and were consistently rather low . in some areas and very high in others. The differences were of a sufficient order of magnitude that it was felt that they could be used, to a degree, to indicate two extreme areas for the present study. It is of interest to note in this connection that the relative stability of area dustfall measurements made in different sections . of an urban community is also generally borne out in a recent report by Cholalc, Schafer and Hoffer.1 . The initial selection of areas for study was thus made on the basis of dustfall measurements. The choice was then narrowed down to delimited areas in high and low dustfall zones in which Table 1.--Number of Households Visited by Public Health Nurses in a House to House Survey of the Low and High Dustfall Areas Area Total1 Both areas ............................................ Low dustfall area...................... High dustfall area................................... 776 337 439 Both areas ............................. ............. 2,670 Low dustfall area...................... 1,231 High dustfall area....................................... 1,439 Nurse 123 Number of Households 193 192 184 84 81 82 109 111 102 Number of Persons 646 655 651 299 291 303 347 364 348 4 202 90, 112 704 338 366' 1 Five households in the high dustfall area were visited by the nurse-supervisor. the socioeconomic conditions and the racial compositions of the residents, a considerable factor in disease incidence, were by and large about the same, based on a visual inspection. The validity of the choices made was subject to test, as indicated below. The. areas; of study were further circumscribed by the shortage of funds. Since the number of families to be visited had to be relatively small so as to insure coverage in a relatively short period of time, the areas chosen were so outlined that a total of 800 family units, about 400 in each area, would be visited, for questioning. It was planned to cover the areas in about 4 to S weeks during the early fall. Thus, based on the estimated number of households that a nurse could probably visit in one day, five public health nurses, one of whom acted as the supervisor, were assigned to the study. Preparation of the survey forms for each day's work by the nurses was handled by a part-time'clerk, who recorded the residence addresses and the family names. Except for one, the public health nurses were strangers to the community. Since all the nurses were to make household visits in both areas, however, thus eventually covering about the same number of faitnlies in each area, it was felt that this one exception would not appreciably modify the data collected. Table d shows the distribution of completed household visits made by the nurses and Indicates satisfactory compliance with that plan. The survey form, which the nurses were to fill out from the answers obtained by questioning a responsible .member of the household, was relatively brief, as shown in figure I. Within the I. Cholak, J.; Schafer, L. J., and Hoffer, R. F.: Collection and Analysis of Solids in Urban Atmospheres, Arch. Indust.-Hyg. & Occup. Med. 2:443, 1950.