Calibration of PurpleAir PA-I and PA-II Monitors Using Daily Mean PM<sub>2.5</sub> Concentrations Measured in California, Washington, and Oregon from 2017 to 2021
Large quantities of real-time particle data are becoming available from low-cost particle monitors. However, it is crucial to determine the quality of these measurements. The largest network of monitors in the United States is maintained by the PurpleAir company, which offers two monitors: PA-I and...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-06-01
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| Series: | Sensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1424-8220/22/13/4741 |
| _version_ | 1797408196241915904 |
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| author | Lance Wallace Tongke Zhao Neil E. Klepeis |
| author_facet | Lance Wallace Tongke Zhao Neil E. Klepeis |
| author_sort | Lance Wallace |
| collection | DOAJ |
| description | Large quantities of real-time particle data are becoming available from low-cost particle monitors. However, it is crucial to determine the quality of these measurements. The largest network of monitors in the United States is maintained by the PurpleAir company, which offers two monitors: PA-I and PA-II. PA-I monitors have a single sensor (PMS1003) and PA-II monitors employ two independent PMS5003 sensors. We determine a new calibration factor for the PA-I monitor and revise a previously published calibration algorithm for PA-II monitors (ALT-CF3). From the PurpleAir API site, we downloaded 83 million hourly average PM<sub>2.5</sub> values in the PurpleAir database from Washington, Oregon, and California between 1 January 2017 and 8 September 2021. Daily outdoor PM<sub>2.5</sub> means from 194 PA-II monitors were compared to daily means from 47 nearby Federal regulatory sites using gravimetric Federal Reference Methods (FRM). We find a revised calibration factor of 3.4 for the PA-II monitors. For the PA-I monitors, we determined a new calibration factor (also 3.4) by comparing 26 outdoor PA-I sites to 117 nearby outdoor PA-II sites. These results show that PurpleAir PM<sub>2.5</sub> measurements can agree well with regulatory monitors when an optimum calibration factor is found. |
| first_indexed | 2024-03-09T03:55:54Z |
| format | Article |
| id | doaj.art-c1f9823d0820401797f3545289ab88ab |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-09T03:55:54Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-c1f9823d0820401797f3545289ab88ab2023-12-03T14:21:55ZengMDPI AGSensors1424-82202022-06-012213474110.3390/s22134741Calibration of PurpleAir PA-I and PA-II Monitors Using Daily Mean PM<sub>2.5</sub> Concentrations Measured in California, Washington, and Oregon from 2017 to 2021Lance Wallace0Tongke Zhao1Neil E. Klepeis2Independent Researcher, Santa Rosa, CA 95049, USAIndependent Researcher, Milpitas, CA 95035, USADepartment of American Indian Studies, San Diego State University (SDSU), San Diego, CA 92182, USALarge quantities of real-time particle data are becoming available from low-cost particle monitors. However, it is crucial to determine the quality of these measurements. The largest network of monitors in the United States is maintained by the PurpleAir company, which offers two monitors: PA-I and PA-II. PA-I monitors have a single sensor (PMS1003) and PA-II monitors employ two independent PMS5003 sensors. We determine a new calibration factor for the PA-I monitor and revise a previously published calibration algorithm for PA-II monitors (ALT-CF3). From the PurpleAir API site, we downloaded 83 million hourly average PM<sub>2.5</sub> values in the PurpleAir database from Washington, Oregon, and California between 1 January 2017 and 8 September 2021. Daily outdoor PM<sub>2.5</sub> means from 194 PA-II monitors were compared to daily means from 47 nearby Federal regulatory sites using gravimetric Federal Reference Methods (FRM). We find a revised calibration factor of 3.4 for the PA-II monitors. For the PA-I monitors, we determined a new calibration factor (also 3.4) by comparing 26 outdoor PA-I sites to 117 nearby outdoor PA-II sites. These results show that PurpleAir PM<sub>2.5</sub> measurements can agree well with regulatory monitors when an optimum calibration factor is found.https://www.mdpi.com/1424-8220/22/13/4741sensorslow-cost particle monitorscalibration factorPurpleAirparticlesPM<sub>2.5</sub> |
| spellingShingle | Lance Wallace Tongke Zhao Neil E. Klepeis Calibration of PurpleAir PA-I and PA-II Monitors Using Daily Mean PM<sub>2.5</sub> Concentrations Measured in California, Washington, and Oregon from 2017 to 2021 Sensors sensors low-cost particle monitors calibration factor PurpleAir particles PM<sub>2.5</sub> |
| title | Calibration of PurpleAir PA-I and PA-II Monitors Using Daily Mean PM<sub>2.5</sub> Concentrations Measured in California, Washington, and Oregon from 2017 to 2021 |
| title_full | Calibration of PurpleAir PA-I and PA-II Monitors Using Daily Mean PM<sub>2.5</sub> Concentrations Measured in California, Washington, and Oregon from 2017 to 2021 |
| title_fullStr | Calibration of PurpleAir PA-I and PA-II Monitors Using Daily Mean PM<sub>2.5</sub> Concentrations Measured in California, Washington, and Oregon from 2017 to 2021 |
| title_full_unstemmed | Calibration of PurpleAir PA-I and PA-II Monitors Using Daily Mean PM<sub>2.5</sub> Concentrations Measured in California, Washington, and Oregon from 2017 to 2021 |
| title_short | Calibration of PurpleAir PA-I and PA-II Monitors Using Daily Mean PM<sub>2.5</sub> Concentrations Measured in California, Washington, and Oregon from 2017 to 2021 |
| title_sort | calibration of purpleair pa i and pa ii monitors using daily mean pm sub 2 5 sub concentrations measured in california washington and oregon from 2017 to 2021 |
| topic | sensors low-cost particle monitors calibration factor PurpleAir particles PM<sub>2.5</sub> |
| url | https://www.mdpi.com/1424-8220/22/13/4741 |
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