The impact of the ecological factor on the growth and distribution of population in major urban agglomerations of the United States.

"An attempt is made to isolate the ecological factor (as measured by an air quality index) among the causes of population change in SMSA's in the United States. Eight types of SMSA's are distinguished in terms of various combinations of a selected set of parameters. Growth is found to have been negligible in SMSA's with an unsatisfactory air quality index. It is noted, however, that the observed relationship applies mainly to the white population and that social and racial factors must also be considered in any analysis of SMSA population change."