The State of Sensor Technology and Air Quality Monitoring

Oral Presentation

Prepared by R. Williams1, R. Long1, M. Beaver1, S. Garvey2
1 - US Environmental Protection Agency, MD E-205-04, 109 T. W. Alexander Drive, Research Triangle Park, NC, 27711, United States
2 - Alion Science and Technology, 1000 Park Forty Plaza, Suite 200, Durham, NC, 27713, United States

Contact Information:; 919-541-2957



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). In particular, the basic performance characteristics of these devices have been examined in comparison to recognized reference monitors. Such characteristics reflect data qualities such as limit of detection, reproducibility, accuracy, bias, and response times. In addition, ancillary characteristics of the sensors such as battery life, ease of use, data transmission and/or recovery procedures have been investigated. The protocols and study designs used to conduct these examinations will be reported. Preliminary results indicate that some sensors having a cost of well under $1000 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 (r^2 > 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 was 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 results from both the field and laboratory evaluations of various sensor types will be reported. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.