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Article

Improving Air Pollutant Metal Oxide Sensor Quantification Practices through: An Exploration of Sensor Signal Normalization, Multi-Sensor and Universal Calibration Model Generation, and Physical Factors Such as Co-Location Duration and Sensor Age

1
Environmental Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
2
Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Ole Hertel
Atmosphere 2021, 12(5), 645; https://doi.org/10.3390/atmos12050645
Received: 24 April 2021 / Revised: 11 May 2021 / Accepted: 15 May 2021 / Published: 19 May 2021
(This article belongs to the Special Issue Atmospheric Trace Gas Source Detection and Quantification)
As low-cost sensors have become ubiquitous in air quality measurements, there is a need for more efficient calibration and quantification practices. Here, we deploy stationary low-cost monitors in Colorado and Southern California near oil and gas facilities, focusing our analysis on methane and ozone concentration measurement using metal oxide sensors. In comparing different sensor signal normalization techniques, we propose a z-scoring standardization approach to normalize all sensor signals, making our calibration results more easily transferable among sensor packages. We also attempt several different physical co-location schemes, and explore several calibration models in which only one sensor system needs to be co-located with a reference instrument, and can be used to calibrate the rest of the fleet of sensor systems. This approach greatly reduces the time and effort involved in field normalization without compromising goodness of fit of the calibration model to a significant extent. We also explore other factors affecting the performance of the sensor system quantification method, including the use of different reference instruments, duration of co-location, time averaging, transferability between different physical environments, and the age of metal oxide sensors. Our focus on methane and stationary monitors, in addition to the z-scoring standardization approach, has broad applications in low-cost sensor calibration and utility. View Full-Text
Keywords: low-cost sensors; universal calibration; methane; sensor normalization; air quality; oil and gas low-cost sensors; universal calibration; methane; sensor normalization; air quality; oil and gas
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MDPI and ACS Style

Okorn, K.; Hannigan, M. Improving Air Pollutant Metal Oxide Sensor Quantification Practices through: An Exploration of Sensor Signal Normalization, Multi-Sensor and Universal Calibration Model Generation, and Physical Factors Such as Co-Location Duration and Sensor Age. Atmosphere 2021, 12, 645. https://doi.org/10.3390/atmos12050645

AMA Style

Okorn K, Hannigan M. Improving Air Pollutant Metal Oxide Sensor Quantification Practices through: An Exploration of Sensor Signal Normalization, Multi-Sensor and Universal Calibration Model Generation, and Physical Factors Such as Co-Location Duration and Sensor Age. Atmosphere. 2021; 12(5):645. https://doi.org/10.3390/atmos12050645

Chicago/Turabian Style

Okorn, Kristen, and Michael Hannigan. 2021. "Improving Air Pollutant Metal Oxide Sensor Quantification Practices through: An Exploration of Sensor Signal Normalization, Multi-Sensor and Universal Calibration Model Generation, and Physical Factors Such as Co-Location Duration and Sensor Age" Atmosphere 12, no. 5: 645. https://doi.org/10.3390/atmos12050645

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