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Sensor Technology and Performance Characteristics
Citation:
Williams, R., R. Long, M. Beaver, R. Duvall, G. Hagler, Sue Kimbrough, E. Thoma, Bill Mitchell, W. Jiao, A. Kaufman, J. Rice, T. Hanley, AND S. Garvey. Sensor Technology and Performance Characteristics. AWMA 2015 Meeting, Raleigh, NC, June 22, 2015.
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
The US EPA is currently involved in detailed laboratory and/or field studies involving a wide variety of low cost air quality sensors currently being made available to potential citizen scientists. These devices include sensors associated with the monitoring of nitrogen dioxide (NO2), ozone (O3), particulate matter (PM), and volatile organic compounds (VOCs) among others. In particular, the basic performance characteristics of these devices are being examined in comparison to recognized reference monitors. Characteristics that reflect data quality include limit of detection, reproducibility, accuracy, bias, and response times. In addition, ancillary characteristics of the sensors are being considered such as battery life, ease of use, data transmission and/or recovery procedures. The protocols and study designs used to conduct these examinations will be reported. Preliminary results indicate that some sensors having a cost of under $2500 have the potential to meet a wide variety of performance characteristics desirable for select air quality monitoring situations. In particular, some gas phase sensors are highly linear (r2 > 0.95) over their response range and with detection limits in the low ppb range. Agreement within +/- 10% of simultaneous measurements from Federal Reference or Federal Equivalent Methods is sometimes observed. Even so, there are challenges to using such sensors including how easily they can be modified to meet extended data collection periods and the impact of interfering species. Select examples from field and/or laboratory evaluations of various low cost sensor types will be reported as well suggested performance characteristics applicable for various monitoring applications. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.
