Evaluating ‘Good Enough’ - An introduction to US EPA Air Sensors NSIM Guidelines and Assessment of Its Utility for Research and Community Air Monitoring Applications

EBEN CROSS, David Hagan, David McClosky, Adriana Peña, Shivang Agarwal, Kirsten Koehler, Peter F. DeCarlo, QuantAQ, Inc.

     Abstract Number: 579
     Working Group: Instrumentation and Methods

Abstract
Recently, the US Environmental Protection Agency (US EPA) released their air sensor performance targets for Non-Regulatory, Supplemental, and Informational Monitoring applications for use outdoors and at fixed locations. These guidelines are an important benchmark for the deployment of air sensors by researchers, regulators and community-based organizations seeking to understand health risk and mitigate local air pollution sources. Despite this progress, challenges and limitations of the NSIM guidelines remain including performance metrics that are too broadly defined, hourly specifications in the context of minute-level pollution transients, and evaluation criteria that fail to reveal fundamental limitations of some sensors.

In this work, we use data from three distinct co-location environments (Baltimore City, MD; Marcus Hook, PA; Rubidoux, CA) to explore whether the new guidelines set data quality goals that are relevant for practical use cases including community and near-reference, sub-regulatory applications. In using data from three distinct environments, we are able to systematically explore the performance of real air sensors across environments that challenge the protocols outlined by EPA. We present recommendations for improvement and call for alternative protocols to ensure coarse aerosol can be reliably measured using air sensors.