EMS Annual Meeting Abstracts
Vol. 20, EMS2023-354, 2023, updated on 06 Jul 2023
EMS Annual Meeting 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

PurpleAir-II sensor correction factors and its use in measuring neighborhood-scale temperature and particulate matter anomalies

Evan Couzo and Christopher Godfrey
Evan Couzo and Christopher Godfrey
  • UNC Asheville, United States of America (ecouzo@unca.edu)

The PurpleAir-II sensor provides low-cost in situ measurements of meteorological variables including temperature and humidity, as well as fine particulate matter (PM2.5) in real time.  The sensors have been used in several studies investigating intracity differences in temperature and PM2.5.  While the adoption and use of low-cost sensors has many benefits, care must be taken to ensure proper calibration and testing.  We have shown previously that the PurpleAir-II sensor has a high bias of 4-5 degrees Fahrenheit and a relative humidity bias of about -17%.  These results were obtained during a continuous measurement period from December 2022 to August 2023 in Asheville, North Carolina.  PurpleAir-II values were compared to temperature measurements with a Campbell Scientific 107 temperature probe and Vaisala HMP45C relative humidity probe.  We now have a longer data record (December 2022 – Summer 2024) spanning multiple seasonal changes and have updated our bias and error calculations.  We have also determined and applied correction factors for PurpleAir-II temperature and relative humidity measurements.  PurpleAir-II PM2.5 concentrations were previously compared to a nearby regulatory PM2.5 monitor maintained by the Asheville Buncombe Air Quality Agency during the same December 2022 – August 2023 measurement period.  PurpleAir-II bias exhibited concentration dependence with low bias at low concentrations and high bias at high concentrations.  We have updated bias and error calculations for PM2.5 concentrations using the longer measurement period, and we have also determined and applied correction factors.  Finally, we describe an upcoming investigation using the PurpleAir-II sensor to measure neighborhood-scale temperature, relative humidity, and PM2.5 in Asheville, North Carolina.  Such measurements will enable us to determine if certain populations are at greater risk for heat stress and PM2.5 exposure.

How to cite: Couzo, E. and Godfrey, C.: PurpleAir-II sensor correction factors and its use in measuring neighborhood-scale temperature and particulate matter anomalies, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-354, https://doi.org/10.5194/ems2023-354, 2023.