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factor in air pollution is a year round phenomena in the Stockton area. High photo -intensity light which increases smog also decreases the entrapping inversion layer. Winter fog in the inversion is self-perpetuating because the sun cannot reach. the earth to warm it and dispel the temperature inversion. In the summer inversion is milder but still present and high intnesity light works adversely on air quality. In winter, fog is a problem. (Conversation with Mr. Bastian, National Weather Service.) During 1972, oxidant levels of greater than .08 ppm were recorded for a total of 49 hours over a period of 20 days. Carbon monoxide levels of greater than 9 ppm were recorded for a total of 25 hours over a period of 4 days. Out of 56 particulate matter samples, a total of 22 were equal to or greater than 100 ug/M . Nitrogen dioxide levels were below the .25 State limits. As with all of the Valley locations, Stockton is located within a thermal inversion layer. On particular days, smog levels will increase due to the lack of air currents and wind movements. It must be noted, however, that during 1972 the air movement was considered "calm" only 9.8% of the time. Using motor vehicle composition emission factors obtained from the California State Air Resources Board, statistics point to a decrease in organic and carbon monoxide (CO) levels over a 30 year period, whereas there will be an increase in the nitrogen oxide (NO2) levels. The existing extensive farming practice causes a continuous change in growing plant cover, leaving much of the land fallow during the winter and bare during the germination and harvest seasons for the primary crop of wheat and beans. The proposed development will include lawn, shrubs and trees, all permanent and never bare, that will more than triple the oxygen return to the atmosphere. The atmospheric air conditioning effect will be increased by more than tenfold, primarily because of the near absence of existing trees on the site. It is estimated that oxygen requirements will be improved as follows: -6-