Santa Ana Winds and Southern California Air Pollution

Abstract:

Santa Ana wind (SAW) events are characterized by strong, dry air moving westward across Southern California, and are typically driven by the formation of high-pressure systems in Nevada during the colder and drier months. As a major periodic shift in meteorological dynamics, SAW events can influence the emissions and transport of pollutants across Southern California, playing a role in long term pollutant exposure trends. In this work, we analyze ozone (O₃) and particulate matter (PM) data recorded at Southern California stations, along with SAW event strength metrics, to assess the influence that SAW events may have on pollutant behavior. By comparing station observations of pollutant levels during SAW events to those of the days immediately preceding and following, we examine the significance of these events with respect to air quality and human health. PM shows an overall decrease in concentrations in the inland sites during SAW events, while coastal site levels are either unaffected or show a slight increase. SAW events show an increase in O₃ at northern sites and a decrease in southern sites. Analyzing the effects SAW events have on air quality can help explain day-to-day pollutant variability, improve pollution prediction efforts, and identify when to take preventative measures for those who are more susceptible to air quality changes.