Evaluation of a low-cost optical particle counter (Alphasense OPC-N2) for ambient air monitoring

Research output: Contribution to journalArticle

Standard

Evaluation of a low-cost optical particle counter (Alphasense OPC-N2) for ambient air monitoring. / Crilley, Leigh R.; Shaw, Marvin; Pound, Ryan; Kramer, Louisa J.; Price, Robin; Young, Stuart; Lewis, Alastair C.; Pope, Francis D.

In: Atmospheric Measurement Techniques, Vol. 11, No. 2, 07.02.2018, p. 709-720.

Research output: Contribution to journalArticle

Harvard

APA

Vancouver

Author

Crilley, Leigh R. ; Shaw, Marvin ; Pound, Ryan ; Kramer, Louisa J. ; Price, Robin ; Young, Stuart ; Lewis, Alastair C. ; Pope, Francis D. / Evaluation of a low-cost optical particle counter (Alphasense OPC-N2) for ambient air monitoring. In: Atmospheric Measurement Techniques. 2018 ; Vol. 11, No. 2. pp. 709-720.

Bibtex

@article{fef00e68595a43fabdc820eaa0e5cb7b,
title = "Evaluation of a low-cost optical particle counter (Alphasense OPC-N2) for ambient air monitoring",
abstract = "A fast-growing area of research is the development of low-cost sensors for measuring air pollutants. The affordability and size of low-cost particle sensors makes them an attractive option for use in experiments requiring a number of instruments such as high-density spatial mapping. However, for these low-cost sensors to be useful for these types of studies their accuracy and precision need to be quantified. We evaluated the Alphasense OPC-N2, a promising low-cost miniature optical particle counter, for monitoring ambient airborne particles at typical urban background sites in the UK. The precision of the OPC-N2 was assessed by co-locating 14 instruments at a site to investigate the variation in measured concentrations. Comparison to two different reference optical particle counters as well as a TEOM-FDMS enabled the accuracy of the OPC-N2 to be evaluated. Comparison of the OPC-N2 to the reference optical instruments shows some limitations for measuring mass concentrations of PM1, PM2.5 and PM10. The OPC-N2 demonstrated a significant positive artefact in measured particle mass during times of high ambient RH (>85{\%}) and a calibration factor was developed based upon °-K{\"o}hler theory, using average bulk particle aerosol hygroscopicity. Application of this RH correction factor resulted in the OPC-N2 measurements being within 33{\%} of the TEOM-FDMS, comparable to the agreement between a reference optical particle counter and the TEOM-FDMS (20{\%}). Inter-unit precision for the 14 OPC-N2 sensors of 22±13{\%} for PM10 mass concentrations was observed. Overall, the OPC-N2 was found to accurately measure ambient airborne particle mass concentration provided they are (i) correctly calibrated and (ii) corrected for ambient RH. The level of precision demonstrated between multiple OPC-N2s suggests that they would be suitable devices for applications where the spatial variability in particle concentration was to be determined.",
author = "Crilley, {Leigh R.} and Marvin Shaw and Ryan Pound and Kramer, {Louisa J.} and Robin Price and Stuart Young and Lewis, {Alastair C.} and Pope, {Francis D.}",
year = "2018",
month = "2",
day = "7",
doi = "10.5194/amt-11-709-2018",
language = "English",
volume = "11",
pages = "709--720",
journal = "Atmos. Meas. Tech. Discuss",
issn = "1867-1381",
publisher = "European Geosciences Union",
number = "2",

}

RIS

TY - JOUR

T1 - Evaluation of a low-cost optical particle counter (Alphasense OPC-N2) for ambient air monitoring

AU - Crilley, Leigh R.

AU - Shaw, Marvin

AU - Pound, Ryan

AU - Kramer, Louisa J.

AU - Price, Robin

AU - Young, Stuart

AU - Lewis, Alastair C.

AU - Pope, Francis D.

PY - 2018/2/7

Y1 - 2018/2/7

N2 - A fast-growing area of research is the development of low-cost sensors for measuring air pollutants. The affordability and size of low-cost particle sensors makes them an attractive option for use in experiments requiring a number of instruments such as high-density spatial mapping. However, for these low-cost sensors to be useful for these types of studies their accuracy and precision need to be quantified. We evaluated the Alphasense OPC-N2, a promising low-cost miniature optical particle counter, for monitoring ambient airborne particles at typical urban background sites in the UK. The precision of the OPC-N2 was assessed by co-locating 14 instruments at a site to investigate the variation in measured concentrations. Comparison to two different reference optical particle counters as well as a TEOM-FDMS enabled the accuracy of the OPC-N2 to be evaluated. Comparison of the OPC-N2 to the reference optical instruments shows some limitations for measuring mass concentrations of PM1, PM2.5 and PM10. The OPC-N2 demonstrated a significant positive artefact in measured particle mass during times of high ambient RH (>85%) and a calibration factor was developed based upon °-Köhler theory, using average bulk particle aerosol hygroscopicity. Application of this RH correction factor resulted in the OPC-N2 measurements being within 33% of the TEOM-FDMS, comparable to the agreement between a reference optical particle counter and the TEOM-FDMS (20%). Inter-unit precision for the 14 OPC-N2 sensors of 22±13% for PM10 mass concentrations was observed. Overall, the OPC-N2 was found to accurately measure ambient airborne particle mass concentration provided they are (i) correctly calibrated and (ii) corrected for ambient RH. The level of precision demonstrated between multiple OPC-N2s suggests that they would be suitable devices for applications where the spatial variability in particle concentration was to be determined.

AB - A fast-growing area of research is the development of low-cost sensors for measuring air pollutants. The affordability and size of low-cost particle sensors makes them an attractive option for use in experiments requiring a number of instruments such as high-density spatial mapping. However, for these low-cost sensors to be useful for these types of studies their accuracy and precision need to be quantified. We evaluated the Alphasense OPC-N2, a promising low-cost miniature optical particle counter, for monitoring ambient airborne particles at typical urban background sites in the UK. The precision of the OPC-N2 was assessed by co-locating 14 instruments at a site to investigate the variation in measured concentrations. Comparison to two different reference optical particle counters as well as a TEOM-FDMS enabled the accuracy of the OPC-N2 to be evaluated. Comparison of the OPC-N2 to the reference optical instruments shows some limitations for measuring mass concentrations of PM1, PM2.5 and PM10. The OPC-N2 demonstrated a significant positive artefact in measured particle mass during times of high ambient RH (>85%) and a calibration factor was developed based upon °-Köhler theory, using average bulk particle aerosol hygroscopicity. Application of this RH correction factor resulted in the OPC-N2 measurements being within 33% of the TEOM-FDMS, comparable to the agreement between a reference optical particle counter and the TEOM-FDMS (20%). Inter-unit precision for the 14 OPC-N2 sensors of 22±13% for PM10 mass concentrations was observed. Overall, the OPC-N2 was found to accurately measure ambient airborne particle mass concentration provided they are (i) correctly calibrated and (ii) corrected for ambient RH. The level of precision demonstrated between multiple OPC-N2s suggests that they would be suitable devices for applications where the spatial variability in particle concentration was to be determined.

U2 - 10.5194/amt-11-709-2018

DO - 10.5194/amt-11-709-2018

M3 - Article

VL - 11

SP - 709

EP - 720

JO - Atmos. Meas. Tech. Discuss

JF - Atmos. Meas. Tech. Discuss

SN - 1867-1381

IS - 2

ER -