The next generation of low-cost personal air quality sensors for quantitative exposure monitoring

Piedrahita, Ricardo; Xiang, Yun; Masson, N.; Ortega, John; Collier, Ashley; Jiang, Yifei; Li, K.; Dick, Robert P.; Lv, Qin; Hannigan, Michael P.; Shang, Li

doi:10.5194/amt-7-3325-2014

Cited by 224 publications

(127 citation statements)

References 37 publications

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“…The growth of small sensors for a range of trace species including ozone has the potential to offer insights on unheralded spatial and temporal timescales (Snyder et al, 2013;Mead et al, 2013;Piedrahita et al, 2014). As illustrated in Fig.…”

Section: Discussionmentioning

confidence: 99%

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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Abstract. Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. Much effort is focused on the reduction of surface levels of ozone owing to its health and vegetation impacts, but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve owing to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner. The review shows that there remain a number of clear challenges for ozone such as explaining surface trends, incorporating new chemical understanding, ozone-climate coupling, and a better assessment of impacts. There is a clear and present need to treat ozone across the range of scales, a transboundary issue, but with an emphasis on the hemispheric scales. New observational opportunities are offered both by satellites and small sensors that bridge the scales.

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Section: Discussionmentioning

confidence: 99%

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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“…In more typical conditions, sensors might respond to other atmospheric species as well. Calibrations of cheap sensors performed in the lab and in the field can differ markedly 3 , and most relationships observed in the field only apply to that location and for a limited time.…”

Section: Keep Testingmentioning

confidence: 99%

“…Portable sensors are becoming a mainstay of health research by showing people's exposure to environmental factors ranging from noise to particulate matter 3,4 . Live pollution data can be integrated into trafficmanagement systems to track the impacts of policies such as low-emissions zones.…”

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confidence: 99%

Validate personal air-pollution sensors

Lewis

Edwards

2016

Nature

244

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call on researchers to test the accuracy of low-cost monitoring devices before regulators are flooded with questionable air-quality data.T he public is increasingly aware of the health and economic costs of air pollution. Poor air quality is linked to over three million deaths each year, and 96% of people in large cities are exposed to pollutant levels that are above recommended limits 1 . The costs of urban air pollution amount to 2% of gross domestic product in developed countries and 5% in developing countries (see go.nature.com/28qv0ka).Media attention and the increasing availability of data are reinvigorating efforts in many countries to tackle air pollution, driven as much by local and national politics as by science.In response, start-up companies are rushing to produce cheap air-monitoring sensors, costing hundreds rather than tens of thousands of pounds. Such devices bridge gaps between sparse government measurements and individuals' wishes to track their personal exposures 2 . In a wealthy city, a single official monitoring station might represent 100,000 people; in emerging economies, one instrument covers millions of citizens.Although personal sensors have not yet achieved their market potential, applications are promising. Portable sensors are becoming a mainstay of health research by showing people's exposure to environmental factors ranging from noise to particulate matter 3,4 . Live pollution data can be integrated into trafficmanagement systems to track the impacts of policies such as low-emissions zones. Affordable air-quality devices are being produced for developing countries. For example, the

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“…The first involves calibrating the sensor in a laboratory over a controlled and well-defined range of conditions (Castell et al, 2017;Mead et al, 2013;Piedrahita et al, 2014), as is standard for calibration of high-fidelity atmospheric chemistry and AQ instrumentation. However, because electrochemical sensors tend to be less selective and more prone to interferences than such higher-fidelity instruments (Lewis et al, 2015), identifying and calibrating over the full range of relevant measurement conditions in the laboratory can be challenging, and the presence of additional interfering components cannot always be anticipated.…”

Section: Introductionmentioning

confidence: 99%

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

et al. 2018

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Abstract. The use of low-cost air quality sensors for air pollution research has outpaced our understanding of their capabilities and limitations under real-world conditions, and there is thus a critical need for understanding and optimizing the performance of such sensors in the field. Here we describe the deployment, calibration, and evaluation of electrochemical sensors on the island of Hawai'i, which is an ideal test bed for characterizing such sensors due to its large and variable sulfur dioxide (SO 2 ) levels and lack of other co-pollutants. Nine custom-built SO 2 sensors were colocated with two Hawaii Department of Health Air Quality stations over the course of 5 months, enabling comparison of sensor output with regulatory-grade instruments under a range of realistic environmental conditions. Calibration using a nonparametric algorithm (k nearest neighbors) was found to have excellent performance (RMSE < 7 ppb, MAE < 4 ppb, r 2 > 0.997) across a wide dynamic range in SO 2 (< 1 ppb, > 2 ppm). However, since nonparametric algorithms generally cannot extrapolate to conditions beyond those outside the training set, we introduce a new hybrid linear-nonparametric algorithm, enabling accurate measurements even when pollutant levels are higher than encountered during calibration. We find no significant change in instrument sensitivity toward SO 2 after 18 weeks and demonstrate that calibration accuracy remains high when a sensor is calibrated at one location and then moved to another. The performance of electrochemical SO 2 sensors is also strong at lower SO 2 mixing ratios (< 25 ppb), for which they exhibit an error of less than 2.5 ppb. While some specific results of this study (calibration accuracy, performance of the various algorithms, etc.) may differ for measurements of other pollutant species in other areas (e.g., polluted urban regions), the calibration and validation approaches described here should be widely applicable to a range of pollutants, sensors, and environments.

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The next generation of low-cost personal air quality sensors for quantitative exposure monitoring

Cited by 224 publications

References 37 publications

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

Validate personal air-pollution sensors

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

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