Calibration of Low-Cost Ozone Detectors to Measure a Key-Indicator of Summertime air Quality in the Salt Lake Valley

The air quality measurement boards developed by the University of Utah department of electrical engineering and evaluated by the department of chemical engineering were calibrated for the measurement of ozone. The redox sensors in these boards had a strong inverse response to increases in ozone concentrations. The boards were calibrated to measure ozone concentrations above 65 ppb with an accuracy within 10%. Temperature changes were found to have a significant effect on the sensor readings, which led to the development of a 3D multivariable calibration surface taking into account both temperature and board data. The boards would likely still be unreliable in the field on cold or windy days. It is my recommendation that further testing be done to characterize the sensor's response at board temperatures less than 29.5 ˚C and at ozone concentrations less than 65 ppb. These are the conditions in which the boards lose accuracy and further testing could remedy this issue. Additionally, it is recommended that the board be tested in atmospherically relevant mixtures of gases to characterize the effect of interaction on the sensor. I further recommend that a standard operating procedure for the board be developed that involves running a script to heat the board for at least 30 minutes before data collection. This operating procedure should also include protecting the board with a plastic housing to minimize convective heat flux over the sensor during operation.