TY - JOUR
T1 - Efficacy of Paired Electrochemical Sensors for Measuring Ozone Concentrations
AU - Zuidema, Christopher
AU - Afshar-Mohajer, Nima
AU - Tatum, Marcus
AU - Thomas, Geb
AU - Peters, Thomas
AU - Koehler, Kirsten
N1 - Funding Information:
This work was supported by the National Institute of Occupational Safety and Health (1R01OH010533 and T42OH008428).
Funding Information:
This work was supported by the National Institute of Occupational Safety and Health (1R01OH010533 and T42OH008428). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention or the Department of Health and Human Services.
Publisher Copyright:
© 2019, © 2019 JOEH, LLC.
PY - 2019/2/1
Y1 - 2019/2/1
N2 - Typical low-cost electrochemical sensors for ozone (O 3 ) are also highly responsive to nitrogen dioxide (NO 2 ). Consequently, a single sensor’s response to O 3 is indistinguishable from its response to NO 2 . Recently, a method for quantifying O 3 concentrations became commercially available (Alphasense Ltd., Essex, UK): collocating a pair of sensors, a typical oxidative gas sensor that responds to both O 3 and NO 2 (model OX-B431) and a second similar sensor that filters O 3 and responds only to NO 2 (model NO2-B43F). By pairing the two sensors, O 3 concentrations can be calculated. We calibrated samples of three NO2-B43F sensors and three OX-B431 sensors with NO 2 and O 3 exclusively and conducted mixture experiments over a range of 0–1.0 ppm NO 2 and 0–125 ppb O 3 to evaluate the ability of the paired sensors to quantify NO 2 and O 3 concentrations in mixture. Although the slopes of the response among our samples of three sensors of each type varied by as much as 37%, the individual response of the NO2-B43F sensors to NO 2 and OX-B431 sensors to NO 2 and O 3 were highly linear over the concentrations studied (R 2 ≥ 0.99). The NO2-B43F sensors responded minimally to O 3 gas with statistically non-significant slopes of response. In mixtures of NO 2 and O 3 , quantification of NO 2 was generally accurate with overestimates up to 29%, compared to O 3 , which was generally underestimated by as much as 187%. We observed changes in sensor baseline over 4 days of experiments equivalent to 34 ppb O 3 , prompting an alternate method of calculating concentrations by baseline-correcting sensor signal. The baseline-correction method resulted in underestimates of NO 2 up to 44% and decreases in the underestimation of O 3 up to 107% for O 3 . Both methods for calculating gas concentrations progressively underestimated O 3 concentrations as the ratio of NO 2 signal to O 3 signal increased. Our results suggest that paired NO2-B43F and OX-B431 sensors permit quantification of NO 2 and O 3 in mixture, but that O 3 concentration estimates are less accurate and precise than those for NO 2 .
AB - Typical low-cost electrochemical sensors for ozone (O 3 ) are also highly responsive to nitrogen dioxide (NO 2 ). Consequently, a single sensor’s response to O 3 is indistinguishable from its response to NO 2 . Recently, a method for quantifying O 3 concentrations became commercially available (Alphasense Ltd., Essex, UK): collocating a pair of sensors, a typical oxidative gas sensor that responds to both O 3 and NO 2 (model OX-B431) and a second similar sensor that filters O 3 and responds only to NO 2 (model NO2-B43F). By pairing the two sensors, O 3 concentrations can be calculated. We calibrated samples of three NO2-B43F sensors and three OX-B431 sensors with NO 2 and O 3 exclusively and conducted mixture experiments over a range of 0–1.0 ppm NO 2 and 0–125 ppb O 3 to evaluate the ability of the paired sensors to quantify NO 2 and O 3 concentrations in mixture. Although the slopes of the response among our samples of three sensors of each type varied by as much as 37%, the individual response of the NO2-B43F sensors to NO 2 and OX-B431 sensors to NO 2 and O 3 were highly linear over the concentrations studied (R 2 ≥ 0.99). The NO2-B43F sensors responded minimally to O 3 gas with statistically non-significant slopes of response. In mixtures of NO 2 and O 3 , quantification of NO 2 was generally accurate with overestimates up to 29%, compared to O 3 , which was generally underestimated by as much as 187%. We observed changes in sensor baseline over 4 days of experiments equivalent to 34 ppb O 3 , prompting an alternate method of calculating concentrations by baseline-correcting sensor signal. The baseline-correction method resulted in underestimates of NO 2 up to 44% and decreases in the underestimation of O 3 up to 107% for O 3 . Both methods for calculating gas concentrations progressively underestimated O 3 concentrations as the ratio of NO 2 signal to O 3 signal increased. Our results suggest that paired NO2-B43F and OX-B431 sensors permit quantification of NO 2 and O 3 in mixture, but that O 3 concentration estimates are less accurate and precise than those for NO 2 .
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U2 - 10.1080/15459624.2018.1540872
DO - 10.1080/15459624.2018.1540872
M3 - Article
C2 - 30412037
AN - SCOPUS:85063162160
SN - 1545-9624
VL - 16
SP - 179
EP - 190
JO - Journal of occupational and environmental hygiene
JF - Journal of occupational and environmental hygiene
IS - 2
ER -