The rise of low-cost sensing for managing air pollution in cities

Kumar, Prashant; Morawska, Lidia; Martani, Claudio; Biskos, George; Neophytou, Marina; Sabatino, Silvana Di; Bell, MC; Norford, Leslie K.; Britter, Rex

doi:10.1016/j.envint.2014.11.019

Cited by 755 publications

(508 citation statements)

References 61 publications

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“…As discussed earlier, U-Pod D5 experienced an electrical 30 issue during the calibration period which resulted in a clear bias throughout the validation dataset. This particular electrical issue points to the challenges of using such sensor platforms in an ambient monitoring context, a topic widely discussed in the air sensor community (Kumar et al 2015). Bias for the other U-Pods was relatively small and on the order of 1 -2 ppbv.…”

Section: Field Calibration Validation Resultsmentioning

confidence: 99%

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

Sadighi

Coffey

Polidori

et al. 2017

Preprint

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Abstract. Sensor networks are being more widely used to characterize and understand compounds in the atmosphere such as ozone and carbon dioxide. This study employs a measurement tool, called the U-Pod, constructed at the University of Colorado Boulder, to investigate spatial and temporal variability of O3 and CO2 in a 314 km 2 area of Riverside County near Los Angeles, 10California. This tool provides low-cost sensors to collect ambient data at non-permanent locations. The U-Pods were calibrated using a pre-deployment field calibration technique; all the U-Pods were collocated with regulatory monitors. After collocation, the U-Pods were deployed in the area mentioned. A subset of pods was deployed at two local regulatory air quality monitoring stations providing validation for the collocation calibration method. Field validation of sensor O3 and CO2 measurements to minute resolution reference observations resulted in R-squared and root mean squared errors (RMSE) of 0.95 -0.97 and 4.4 -15 7.2 ppbv for O3 and 0.79 and 15 ppmv CO2, respectively. Using the deployment data, ozone and carbon dioxide concentrations were observed to vary on this small spatial scale. In the analysis based on hourly binned data, the median R-squared values between all possible U-Pod pairs varied from 0.52 to 0.86 for ozone during the deployment. The medians of absolute differences were calculated between all possible pod pairs, 21 pairs total. The median values of those median absolute differences for each hour of the day varied between 2.2 and 9.3 ppb for the ozone deployment. For carbon dioxide, distributions 20 of all measurements vary from 413 -425 ppm during the calibration (collocation) and 406 -472 during the deployment. Since median differences between U-Pod concentrations during deployment are larger than the respective root mean square error values for ozone and carbon dioxide, we can conclude that there is spatial variability in these pollutants across the study area. This is important because it means that citizens may be exposed to more ozone than they would assume based on current regulatory monitoring. 25Atmos. Meas. Tech. Discuss., https://doi

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Section: Field Calibration Validation Resultsmentioning

confidence: 99%

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

Sadighi

Coffey

Polidori

et al. 2017

Preprint

View full text Add to dashboard Cite

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“…Emerging low-cost sensor technology has the potential to extend the official monitoring network significantly, and improve our understanding of local urban air pollution. Miniaturized and affordable sensors enable citizens to measure their environment in more detail in space and time 5 (Kumar et al, 2015). However, most sensors are still in an experimental stage and suffer from various technical issues which limit their applicability.…”

Section: Introductionmentioning

confidence: 99%

Practical field calibration of electrochemical NO<sub>2</sub> sensors for urban air quality applications

Mijling

Jiang

Jonge

et al. 2017

Preprint

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Abstract. In many urban areas the population is exposed to elevated levels of air pollution. However, air quality is usually 10 only measured at a few locations. These measurements provide a general picture of the state of the air, but they are unable to monitor local differences. Since a few years new low-cost sensor technology is available, which has the potential to extend the official monitoring network significantly. These sensors, however, are still in an experimental stage and suffer from various technical issues which limit their applicability.This study explores the added value of alternative air quality measurements, focusing on nitrogen dioxide (NO 2 ) in 15Amsterdam, the Netherlands. 16 low-cost air quality sensor devices were built and distributed among volunteers living close to roads with high traffic volume for a two-month measurement campaign.Careful calibration of individual sensors is essential to measure ambient concentrations of NO 2 significantly. Field calibration was done next to an air monitoring station during an 8-day period, resulting in R 2 ranging from 0.3 to 0.7. The NO 2 accuracy can be improved by including temperature and humidity measurements from an additional low-cost sensor, R 2 20 ranging from 0.6 to 0.9. Recalibration is crucial, as all sensors show significant signal drift after the two-month measurement campaign. The measurement series between the calibration periods can be corrected in hindsight by taking a weighted average of the calibration coefficients.Validation against an independent air monitoring station shows good agreement. Using our approach, the standard deviation of a typical sensor device for NO 2 measurements was found to be 7 μg m -3 . This shows that, if properly treated, low-cost 25 sensors based on the current generations of electrochemical NO 2 sensors may provide useful complementary data on local air quality in an urban setting.

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“…However, the question remains as to whether the un-L. R. Crilley et al: Evaluation of a low-cost optical particle counter (Alphasense OPC-N2) certain quality of data from these low-cost sensors can be of value when attempting to determine pollutant concentrations at high spatial resolution (Kumar et al, 2015). Sensors for both gases and particles can suffer from drift and a number of interference artefacts such as relative humidity (RH), temperature and other gas-phase species (Lewis et al, 2016;Mueller et al, 2017;Popoola et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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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 lowcost 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 colocating 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 PM 1 , PM 2.5 and PM 10 . 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 κ-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 PM 10 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.

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The rise of low-cost sensing for managing air pollution in cities

Abstract: Britter, R., 2015. The rise of low cost sensing for managing air pollution in cities. Environment International 75,[199][200][201][202][203][204][205]. Online link: http://dx

Cited by 755 publications

References 61 publications

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

Practical field calibration of electrochemical NO<sub>2</sub> sensors for urban air quality applications

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

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The rise of low-cost sensing for managing air pollution in cities

Abstract: Britter, R., 2015. The rise of low cost sensing for managing air pollution in cities. Environment International 75,[199][200][201][202][203][204][205]. Online link: http://dx

Cited by 755 publications

References 61 publications

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

Practical field calibration of electrochemical NO&lt;sub&gt;2&lt;/sub&gt; sensors for urban air quality applications

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

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Practical field calibration of electrochemical NO<sub>2</sub> sensors for urban air quality applications