The San Joaquin Valley (SJV) of California is one of the most polluted regions in the United States, and is classified by the U.S. Environmental Protection (EPA) as a serious nonattainment area for both ozone and fine particulate matter (PM2.5). Pollution sources in SJV accounts for about 14 percent of the total statewide criteria pollutant emissions. The Valley ranks the second with respect to the nations’ worst ozone air quality. Although there has been some progress in SJV over the past ten years, the rate of progress has been slow in comparison to other areas of the California State. [23]

To bring the entire Valley into attainment of the PM2.5 standard, it is necessary to find out past and present movements of PM2.5 to estimate the future movements of PM2.5. In order to make it possible, the first and foremost step to take is to do time series analysis of this matter, so it could be used to plan for the future in reducing PM2.5 to attainment standard. Basic time series analysis methods, such as plotting raw data and decomposition, were used and various additional methods, such as ACF, ARIMA, and regression analysis, were applied.