Evaluating Small Spatial Scale Ozone Levels in Riverside, CA using a Low-Cost Sensor Network

Ground-level ozone is an EPA criteria pollutant that causes negative human health effects, and damages plant life. Currently, it is the responsibility of individual states to designate attainment areas within their borders often by means of regional air quality boards. The goal of this project is to show that ozone has spatial and temporal variability on smaller scales than preexisting attainment areas and demonstrate the reliability of finer resolution air quality data using a low-cost sensor system (called a UPod) in the field. During the summer of 2015, thirteen UPods were collocated in Riverside, CA at the SCAQMD (South Coast Air Quality Management District) Rubidoux reference station for two weeks at the end of July. Following, the UPods were deployed throughout a small (10x10 km) region for two months then returned to Rubidoux for a post calibration. Ozone data was collected using e2v MiCS-2611 metal oxide sensors (SGX Tech.) at a frequency of about 4-6 times per minute - which were later minute averaged. Field normalization calibrations were generated converting sensor signal outputs (mV) to concentrations (ppbv) and cross-validation against reference-grade monitors in the field were 3-6.8 ppbv (RMSE) at minute resolution. Further analysis will include examining the data for statistical information through space and time exploring variability. Having cost effective, reliable and fine-resolution air quality data in a region displaying variability may help regulatory agencies make policy decisions that can impact people living on community scales.