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Assessing the accuracy of commercially available gas sensors for the measurement of ambient ozone and nitrogen dioxide
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11 2018
Source: J Occup Environ Hyg. 15(11):782-791 -
Alternative Title:J Occup Environ Hyg
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Description:The objective of the National Institute for Occupational Safety and Health (NIOSH) accuracy criterion is to ensure that measurements from monitoring devices are within ±25% of the true concentration of the analyte with 95% certainty. To determine whether NO| and O| sensors meet this criterion, three commercially available units (Cairclip O|/NO|, Aeroqual NO|, and Aeroqual O| sensors) were co-located three times with validated instruments (NO| chemiluminescence [NO|] and photometric O| analyzers [O|]) at an outdoor monitoring station. As cofactors of sensor performance such as temperature (T) and relative humidity (RH) potentially influence the response of NO| and O| sensors, corrections for cofactors were made by using T, RH, and the sensor measurements to predict measurements made by NO| and O| during the first co-location period (training dataset). The developed models were tested in the merged data obtained from the second and third co-location periods (testing dataset). In the training and testing datasets, the mean NO| as measured by NO| was 4.6 ppb (range = 0.4-35 ppb) and 9.4 ppb (range = 1-37 ppb), respectively. The mean O| in the training and testing datasets as measured by O| was 38.8 ppb (range = 1-65 ppb) and 35.7 ppb (range = 1-61 ppb), respectively. None of the sensor measurements in the training dataset were within the NIOSH accuracy criterion (mean error ≥25%). After correcting for cofactors of sensor performance, the accuracy of the Cairclip O|/NO| and the Aeroqual O| sensors considerably improved when tested with the testing dataset (mean error = -1% and 14%, respectively). However, the Aeroqual NO| sensor had an error that was not within ±25%. Raw measurements from the tested sensors may be unsuitable for assessing workers' exposure to NO| and O|. Corrections for cofactors of Cairclip O|/NO| and Aeroqual O| sensor performance are required for more accurate occupational exposure assessment.
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Pubmed ID:30156975
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Pubmed Central ID:PMC6324576
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