Air Sensor Performance Targets and Testing Protocols
On this page:
There has been a dramatic increase in the use of air sensors to measure air quality, however, it is widely known that sensor data quality is highly variable. The lack of consistent testing protocols to evaluate the performance of air sensors makes it difficult to understand how air sensor data compares to that of regulatory air monitors.
EPA has recognized that air sensors will not meet the stringent requirements for air quality instruments used for regulatory purposes, although they may have utility for a variety of non-regulatory applications such as understanding local air quality, identifying hot spots, or helping to identify sites for regulatory monitors.
EPA has been engaged in a variety of activities to help advance the understanding of air sensors. Initial efforts involved two workshops to gather perspectives from subject matter experts, air sensor manufacturers, air pollution regulatory entities, and other stakeholders on the the following topics:
- State of air sensor technologies
- Potential approaches for setting performance targets and standards
- Lessons learned from other organizations establishing performance targets for measurement technologies.
The first workshop in 2018 focused on fine particulate matter (PM2.5), which is particulate matter with aerodynamic diameters of 2.5 microns or less) and ozone (O3). The second workshop in 2019 addressed particulate matter with aerodynamic diameters of 10 microns or less (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO). To inform the workshop discussions and development of testing protocols and performance targets for air sensors, EPA conducted two scientific literature reviews that identified the performance attributes most often used to characterize air quality monitoring instrument performance and examined results from field and laboratory air sensor performance evaluations.
In February 2021, EPA published two air sensor performance target reports, one for O3 sensors and the other for PM2.5 sensors. The objective of these reports is to provide a consistent set of testing protocols, metrics, and target values to evaluate the performance of air sensors specifically for non-regulatory supplemental and informational monitoring (NSIM) applications for use outdoors and at fixed locations. The reports include protocols for two testing scenarios:
- Base testing, which includes field evaluation
- Enhanced testing, which includes laboratory evaluation
These reports provide the following:
- A description of the motivation and considerations for developing the reports
- An outline of the testing protocols
- Details on how to calculate the recommended performance metrics
- A list of target values for each metric based on the current state of the science
- Reporting templates for consistent reporting of testing results
The intended audience for these reports includes potential testing organizations, sensor manufacturers, and sensor developers. It is anticipated that a variety of consumers, including state, local, and tribal agencies, federal government agencies, community groups, citizen scientists, academia, and others will benefit from the consistent presentation of testing results to identify sensor technologies that would be best suited for their non-regulatory supplemental and informational monitoring application(s) and to understand the performance of the air sensor technologies. Consumers may also choose to conduct these testing protocols.
- Presentation on Air Sensor Performance Testing as part of the EPA's Tools and Resources Webinar Series (March 24, 2021)
- Presentations from the Deliberating Performance Targets for Air Quality Sensors Workshop (June 25-27, 2018)
- Presentations from the Deliberating Performance Targets for Air Quality Sensors Workshop (July 16-17, 2019)
Related Articles and Publications
- Deliberating performance targets: Follow-on workshop discussing PM10, NO2, CO, and SO2 air sensor targets
- Deliberating performance targets workshop: Potential paths for emerging PM2.5 and O3 air sensor progress
- Air Sensors 2018: Deliberating Performance Targets - A summary of highlights and outcomes from EPA’s Air Sensors 2018 Workshop
- 2018 Peer Review and Supporting Literature Review of Air Sensor Technology Performance Targets
- Peer Review and Supporting Literature Review of Air Sensor Technology Performance Targets: 2019 Supplemental
ASTM Standards in Development
EPA participates in two ASTM International subcommittees developing standards of practice and test methods for evaluating the performance of ambient and indoor air quality sensors. ASTM International develops voluntary consensus standards for a variety of products and services.