Date of Award


Document Type


Degree Name

Master of Science (MS)

Program Name

Environmental Policy and Management

Capstone Instructor

Dr. Elizabeth D'Andrea


The San Joaquin Valley (SJV) is the largest producer of dairy in California and the United States. The SJV consists of eight counties which held approximately 1.5 million dairy cows in 2014. The region continually fails to meet air quality standards for particulate matter under 2.5 micrometers (PM2.5) set by the Environmental Protection Agency under the Clean Air Act. Previous studies have shown that the presence of dairy cows is a contributing factor increasing the amount of PM2.5in the air. This study investigates the relationship between the number of dairy cows, dairies, and cows per dairy with the number of days where PM2.5 was the dominant pollutant (PM2.5 days) and the concentration of PM2.5 throughout the eight counties in the SJV. Using the Spearman’s Rank Correlation Coefficient and the data collected from 2002-2014, the paired data sets were tested for association. Fresno, Kings, and Stanislaus Counties showed a strong, positive association between the number of cows and PM2.5 days while Kern and Merced Counties showed a moderate, positive association. This suggests that in these counties as the number of dairy cows increased the number of PM2.5 days also increased. This also suggests that more dairy cows within a county contribute to increased PM2.5 in the air. Other associations observed in the results of this study were different throughout the counties suggesting that no obvious relationship exists. This study could be approved upon by collecting PM2.5 data directly from dairy farms and strategic areas across the county rather than depending on centralized air monitoring sites.



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