Deployment, Calibration, and Cross-Validation of Low-Cost Electrochemical Sensors for Carbon Monoxide, Nitrogen Oxides, and Ozone for an Epidemiological Study
Abstract
:1. Introduction
2. Materials and Methods
2.1. Study Context
2.2. Low-Cost Monitor Deployment
2.3. Low-Cost Monitor and Sensor Descriptions
2.4. Co-Location of LCMs with Air Quality System Monitors
2.5. Sensor Quality Assurance and Data Exclusion Criteria
2.6. Calibration Models
2.7. Cross Validation and Model Evaluation
3. Results
3.1. Site Descriptive Characteristics and LCM Co-Location
3.2. Evaluation of Calibration Models
4. Discussion
5. Conclusions
Supplementary Materials
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
Appendix A
Appendix A.1. Background
Appendix A.2. Methods
- Consider all pairwise comparisons for sensors that were ever co-located, and create a matrix for both WE and Aux that records these pairwise average differences.
- Fill in missing data using a weighting scheme based on the time of co-location and relying on multiple degrees of separation.
- After several iterations, the sensor differences relative to a single reference sensor are obtained, which can be used to adjust the sensor signal (mV).
Appendix A.3. Results and Discussion
Fit in Puget Sound | Evaluated in Baltimore | |||||||
---|---|---|---|---|---|---|---|---|
# Co-Location Sites | # Monitor Days Co-Location | CV-RMSE (ppb) | CV-R2 | # Co-Location Sites | # Monitor Days Co-location | CV-RMSE (ppb) | CV-R2 | |
CO | 1 | 494 | 19 | 0.97 | 2 | 498 | 56 | 0.51 |
NO | 1 | 520 | 5 | 0.89 | 4 | 1604 | 8 | 0.45 |
NO2 | 1 | 507 | 6 | 0.22 | 4 | 2029 | 6 | 0.20 |
CO | NO | NO2 | |||||
---|---|---|---|---|---|---|---|
Model | Terms | CV-RMSE (ppb) | CV-R2 | CV-RMSE (ppb) | CV-R2 | CV-RMSE (ppb) | CV-R2 |
B2 | Pre-adjusted WE, pre-adjusted Aux | 51 | 0.53 | 7 | 0.61 | 5 | 0.33 |
B3 | Model B2 with temperature and RH | 39 | 0.73 | 7 | 0.58 | 5 | 0.40 |
B4 | Model B3 with WE–temperature and WE–RH interactions | 36 | 0.76 | 7 | 0.62 | 5 | 0.36 |
B5 | Model B3 with WE– and Aux–temperature and WE– and Aux–RH interactions | 37 | 0.75 | 7 | 0.64 | 5 | 0.29 |
B6 | Model B2 with WE–temperature spline and WE–RH spline interactions | 41 | 0.70 | 7 | 0.63 | 5 | 0.41 |
B7 | Model B4 with WE–Aux interaction | 37 | 0.74 | 7 | 0.62 | 5 | 0.45 |
B8 | Model B4 with WE spline | 38 | 0.74 | 7 | 0.61 | 5 | 0.36 |
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Model | Analyte(s) | Sensor Noise (ppb) 1 | Range (ppm) 2 | Reference |
---|---|---|---|---|
CO-B4 | CO | 4 | 1000 | [42] |
NO-B4 | NO | 15 | 20 | [43] |
NO2-B43F | NO2 | 12 | 20 | [44] |
OX-B431 | O3, NO2 | 4 | 20 | [45] |
Agency Site | Site Type | # LCMs Ever Co-Located | Co-Location Monitor-Days (Weeks) | CO (ppb) Mean ± SD 1 | NO (ppb) Mean ± SD 1 | NO2 (ppb) Mean ± SD 1 | O3 (ppb) Mean ± SD 1 | Avg Temp (°C) Mean ± SD 2 | Avg RH (%) Mean ± SD 2 |
---|---|---|---|---|---|---|---|---|---|
Beacon Hill | Suburban | 54 | 204,498 (99) | 223 ± 89 | 6 ± 10 | 11 ± 5 | 20 ± 9 | 11 ± 4 | 76 ± 12 |
10th and Weller | Urban | 1 3 | 525 (89) | 422 ± 131 | 27 ± 18 | 20 ± 7 | --- 4 | 13 ± 5 | 72 ± 11 |
Gas | Terms | Model Number | CV-RMSE (ppb) | CV-R2 |
---|---|---|---|---|
CO | Manufacturer’s sensor-specific slope and intercept 1 | 0 | 150 | 0.49 |
WE, Aux, and sensor ID | 1 | 29 | 0.94 | |
WE, Aux, sensor ID, temperature, RH, and WE–temperature and WE–RH interactions | 3 | 18 | 0.97 | |
NO | Manufacturer’s sensor-specific slope and intercept 1 | 0 | 36 | 0.41 |
WE, Aux, and sensor ID | 1 | 2 | 0.97 | |
WE, Aux, Sensor ID, and temperature and RH splines 2 with WE interactions | 4 | 2 | 0.97 | |
NO2 | Manufacturer’s sensor-specific slope and intercept 1 | 0 | 24 | 0.08 |
WE, Aux, and sensor ID | 1 | 5 | 0.35 | |
WE, Aux, Sensor ID, temperature and RH splines 2 with WE interactions, and [CO]CO-B4 3 | 4 | 3 | 0.79 | |
O3 | Manufacturer’s sensor-specific slope and intercept 1 | 0 | 41 | 0.04 |
WE, Aux, and sensor ID | 1 | 5 | 0.66 | |
WE, Aux, Sensor ID, temperature and RH splines 2 with WE interactions, and [NO2]NO2-B43F 4 | 4 | 4 | 0.81 |
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Zuidema, C.; Schumacher, C.S.; Austin, E.; Carvlin, G.; Larson, T.V.; Spalt, E.W.; Zusman, M.; Gassett, A.J.; Seto, E.; Kaufman, J.D.; et al. Deployment, Calibration, and Cross-Validation of Low-Cost Electrochemical Sensors for Carbon Monoxide, Nitrogen Oxides, and Ozone for an Epidemiological Study. Sensors 2021, 21, 4214. https://doi.org/10.3390/s21124214
Zuidema C, Schumacher CS, Austin E, Carvlin G, Larson TV, Spalt EW, Zusman M, Gassett AJ, Seto E, Kaufman JD, et al. Deployment, Calibration, and Cross-Validation of Low-Cost Electrochemical Sensors for Carbon Monoxide, Nitrogen Oxides, and Ozone for an Epidemiological Study. Sensors. 2021; 21(12):4214. https://doi.org/10.3390/s21124214
Chicago/Turabian StyleZuidema, Christopher, Cooper S. Schumacher, Elena Austin, Graeme Carvlin, Timothy V. Larson, Elizabeth W. Spalt, Marina Zusman, Amanda J. Gassett, Edmund Seto, Joel D. Kaufman, and et al. 2021. "Deployment, Calibration, and Cross-Validation of Low-Cost Electrochemical Sensors for Carbon Monoxide, Nitrogen Oxides, and Ozone for an Epidemiological Study" Sensors 21, no. 12: 4214. https://doi.org/10.3390/s21124214
APA StyleZuidema, C., Schumacher, C. S., Austin, E., Carvlin, G., Larson, T. V., Spalt, E. W., Zusman, M., Gassett, A. J., Seto, E., Kaufman, J. D., & Sheppard, L. (2021). Deployment, Calibration, and Cross-Validation of Low-Cost Electrochemical Sensors for Carbon Monoxide, Nitrogen Oxides, and Ozone for an Epidemiological Study. Sensors, 21(12), 4214. https://doi.org/10.3390/s21124214