Effects of aerosol type and simulated aging on performance of low-cost PM sensors

Tryner, Jessica; Mehaffy, John; Miller‐Lionberg, Daniel; Volckens, John

doi:10.1016/j.jaerosci.2020.105654

Cited by 73 publications

(81 citation statements)

References 27 publications

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“…Tryner et al [ 25 ] found good agreement ( R 2 ≥ 0.98) among SPS30 sensors and TEOM for PM 2.5 measurements of ammonium sulfate (concentration < 1025 µg/m 3 ) and ARD (concentration <540 µg/m 3 ), which is similar to our findings. For salt, slope values were closer to unity for most PM metrics, meeting EPA and NIOSH performance criteria.…”

Section: Discussionsupporting

confidence: 92%

“…The authors also found moderate to high precision among OPC-N2 sensors used in the experiment (CV = 4.4% to 16%). Tryner et al [ 25 ] evaluated SPS30 sensors for various aerosol types, such as ammonium sulfate, ARD, polystyrene latex spheres (PSL), and wood smoke, in a laboratory setting. The authors compared the results with those of the TEOM, SMPS, and APS reference sensors and reported that the PM 2.5 mass concentration calculated by SPS30 was highly linear with the results obtained from the reference instruments for all aerosol types at a concentration greater than 540 µg/m 3 .…”

Section: Introductionmentioning

confidence: 99%

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Laboratory Evaluation of Low-Cost Optical Particle Counters for Environmental and Occupational Exposures

Sousan

Regmi

Park

2021

Sensors

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Low-cost optical particle counters effectively measure particulate matter (PM) mass concentrations once calibrated. Sensor calibration can be established by deriving a linear regression model by performing side-by-side measurements with a reference instrument. However, calibration differences between environmental and occupational settings have not been demonstrated. This study evaluated four commercially available, low-cost PM sensors (OPC-N3, SPS30, AirBeam2, and PMS A003) in both settings. The mass concentrations of three aerosols (salt, Arizona road dust, and Poly-alpha-olefin-4 oil) were measured and compared with a reference instrument. OPC-N3 and SPS30 were highly correlated (r = 0.99) with the reference instrument for all aerosol types in environmental settings. In occupational settings, SPS30, AirBeam2, and PMS A003 exhibited high correlation (>0.96), but the OPC-N3 correlation varied (r = 0.88–1.00). Response significantly (p < 0.001) varied between environmental and occupational settings for most particle sizes and aerosol types. Biases varied by particle size and aerosol type. SPS30 and OPC-N3 exhibited low bias for environmental settings, but all of the sensors showed a high bias for occupational settings. For intra-instrumental precision, SPS30 exhibited high precision for salt for both settings compared to the other low-cost sensors and aerosol types. These findings suggest that SPS30 and OPC-N3 can provide a reasonable estimate of PM mass concentrations if calibrated differently for environmental and occupational settings using site-specific calibration factors.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Laboratory Evaluation of Low-Cost Optical Particle Counters for Environmental and Occupational Exposures

Sousan

Regmi

Park

2021

Sensors

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“…The high correlations may be because the manufacturer calibrates the SPS30 PM sensors with potassium chloride particles [ 29 ]. Our result is consistent with a previous study that reported R 2 = 0.98 for PM 2.5 when comparing the SPS30 to a high-cost PM reference instrument using ammonium sulfate particles [ 27 ].…”

Section: Resultssupporting

confidence: 93%

“…After careful review of existing low-cost PM and VOC sensors, we chose the SPS30 PM sensor and SGP30 VOC sensor as candidates for our GeoAir design due to their high accuracy, low cross-unit variability, and long-term stability, as reported in the literature [ 25 , 26 , 27 ] and in the field evaluation conducted by the Air Quality Sensor Performance Evaluation Center (AQ-SPEC) in the South Coast Air Quality Management District (SCAQMD, USA) [ 28 ]. The ease of software integration between SGP30 and SPS30 was another reason that both sensors were selected from the same manufacturer.…”

Section: Methodsmentioning

confidence: 99%

GeoAir—A Novel Portable, GPS-Enabled, Low-Cost Air-Pollution Sensor: Design Strategies to Facilitate Citizen Science Research and Geospatial Assessments of Personal Exposure

Park

Sousan

Streuber

et al. 2021

Sensors

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The rapid evolution of air sensor technologies has offered enormous opportunities for community-engaged research by enabling citizens to monitor the air quality at any time and location. However, many low-cost portable sensors do not provide sufficient accuracy or are designed only for technically capable individuals by requiring pairing with smartphone applications or other devices to view/store air quality data and collect location data. This paper describes important design considerations for portable devices to ensure effective citizen engagement and reliable data collection for the geospatial analysis of personal exposure. It proposes a new, standalone, portable air monitor, GeoAir, which integrates a particulate matter (PM) sensor, volatile organic compound (VOC) sensor, humidity and temperature sensor, LTE-M and GPS module, Wi-Fi, long-lasting battery, and display screen. The preliminary laboratory test results demonstrate that the PM sensor shows strong performance when compared to a reference instrument. The VOC sensor presents reasonable accuracy, while further assessments with other types of VOC are needed. The field deployment and geo-visualization of the field data illustrate that GeoAir collects fine-grained, georeferenced air pollution data. GeoAir can be used by all citizens regardless of their technical proficiency and is widely applicable in many fields, including environmental justice and health disparity research.

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“…The low cost of outdoor PurpleAir sensors ($230-$260 U.S. dollars) has enabled them to be widely used with thousands of sensors publicly reporting across the U.S. Previous work has explored the performance and accuracy of the PurpleAir sensors (Magi et al, 2019;Feenstra et al, 2019;Mehadi et al, 2019;Malings et al, 2019;Kim et al, 2019;Sayahi et al, 2019;Tryner et al, 2020a;Singer and Delp, 2018;Kelly et al, 2017;Li et al, 2020;Wang et al, 2020b;Gupta et al, 2018;Delp and Singer, 2020;Zou et al, 2020b;Stavroulas et al, 2020;Holder et al, 2020;Ardon-Dryer et al, 2020;Schulte et al, 2020;Zou et al, 2020a;Robinson, 2020;Bi et al, 2020) and their dual Plantower PMS5003 laser scattering particle sensors (He et al, 2020;Tryner et al, 2019;Kuula et al, 2019;Ford et al, 2019;Si et al, 2020;Zou et al, 2020b;Tryner et al, 2020b). Although not true of all types of PM2.5 sensors, previous work with PurpleAir sensors and other models of Plantower sensors have shown that the sensors are precise, with sensors of the same model measuring similar PM2.5 concentrations (Barkjohn et al, 2020a;Pawar and Sinha, 2020;Malings et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Development and Application of a United States wide correction for PM<sub>2.5</sub> data collected with the PurpleAir sensor

Barkjohn¹,

Gantt²,

Clements³

2020

Preprint

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Abstract. PurpleAir sensors which measure particulate matter (PM) are widely used by individuals, community groups, and other organizations including state and local air monitoring agencies. PurpleAir sensors comprise a massive global network of more than 10,000 sensors. Previous performance evaluations have typically studied a limited number of PurpleAir sensors in small geographic areas or laboratory environments. While useful for determining sensor behavior and data normalization for these geographic areas, little work has been done to understand the broad applicability of these results outside these regions and conditions. Here, PurpleAir sensors operated by air quality monitoring agencies are evaluated in comparison to collocated ambient air quality regulatory instruments. In total, almost 12,000 24-hour averaged PM2.5 measurements from collocated PurpleAir sensors and Federal Reference Method (FRM) or Federal Equivalent Method (FEM) PM2.5 measurements were collected across diverse regions of the United States (U.S.), including 16 states. Consistent with previous evaluations, under typical ambient and smoke impacted conditions, the raw data from PurpleAir sensors overestimate PM2.5 concentrations by about 40 % in most parts of the U.S. A simple linear regression reduces much of this bias across most U.S. regions, but adding a relative humidity term further reduces the bias and improves consistency in the biases between different regions. More complex multiplicative models did not substantially improve results when tested on an independent dataset. The final PurpleAir correction reduces the root mean square error (RMSE) of the raw data from 8 µg m−3 to 3 µg m−3 with an average FRM or FEM concentration of 9 µg m−3. This correction equation, along with proposed data cleaning criteria, has been applied to PurpleAir PM2.5 measurements across the U.S. in the AirNow Fire and Smoke Map (fire.airnow.gov) and has the potential to be successfully used in other air quality and public health applications.

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Effects of aerosol type and simulated aging on performance of low-cost PM sensors

Cited by 73 publications

References 27 publications

Laboratory Evaluation of Low-Cost Optical Particle Counters for Environmental and Occupational Exposures

Laboratory Evaluation of Low-Cost Optical Particle Counters for Environmental and Occupational Exposures

GeoAir—A Novel Portable, GPS-Enabled, Low-Cost Air-Pollution Sensor: Design Strategies to Facilitate Citizen Science Research and Geospatial Assessments of Personal Exposure

Development and Application of a United States wide correction for PM<sub>2.5</sub> data collected with the PurpleAir sensor

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Effects of aerosol type and simulated aging on performance of low-cost PM sensors

Cited by 73 publications

References 27 publications

Laboratory Evaluation of Low-Cost Optical Particle Counters for Environmental and Occupational Exposures

Laboratory Evaluation of Low-Cost Optical Particle Counters for Environmental and Occupational Exposures

GeoAir—A Novel Portable, GPS-Enabled, Low-Cost Air-Pollution Sensor: Design Strategies to Facilitate Citizen Science Research and Geospatial Assessments of Personal Exposure

Development and Application of a United States wide correction for PM&lt;sub&gt;2.5&lt;/sub&gt; data collected with the PurpleAir sensor

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Product

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About

Development and Application of a United States wide correction for PM<sub>2.5</sub> data collected with the PurpleAir sensor