An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Air Sensor Toolbox

Air Sensor Toolbox: What is EPA Doing?

Sensor Performance Evaluation and Application Research (SPEAR)

EPA conducts research to advance the development and application of next generation air monitoring through its Sensor Performance Evaluation and Application Research (SPEAR) initiative.  SPEAR focuses on the growing air sensor revolution that is providing lower-cost, portable and user-friendly monitoring devices for use by the public and others interested in learning about air quality. Sensors are being developed and used in a variety of ways to learn more about personal exposures to air pollutants and to understand the impact of emissions from traffic, industry or other sources at the local or even street level.   

EPA is supporting the advancement of air sensor technology by evaluating and testing commercial devices and developing and testing new instruments using miniatured sensors and other technologies. Efforts to advance lower-cost and portable air quality monitoring capabilities will:

  • Enhance current monitoring activities by states, tribes and communities.
  • Provide new data of air quality at the local level and near air pollution sources.
  • Improve access to air monitors for the public interested in getting information about their air quality.
  • Provide more cost-effective monitoring to help better characterize air quality and air pollutant emissions.

Marketplace Realities

A growing number of air sensors for monitoring air quality are being made commercially available, encouraging more widespread use by individuals, citizen groups, researchers, regulatory officials, and in networks implemented by the private sector.

A wide variety of air sensor technologies currently exist in the market that offer streaming and real-time data capabilities. They vary in size, design, purpose (indoor or outdoor use), type of pollutants measured, power, and communications capabilities. Many cities in the United States currently have air sensor networks operating, with data collected privately or for sharing with the public. In addition, many citizens are procuring sensors for their private use to better understand their exposure to air pollution.

The reliability of these technologies, particularly over long periods of time, is currently not well known. As the technology is in a state of rapid innovation, new versions of air sensors are coming onto the market frequently. To understand whether these technologies produce reliable air pollution data, it is important to compare their performance against well-proven measurement methods. EPA is one of the recognized leaders in evaluating and testing these technologies, sharing information about their performance, as well as applying them in field studies with citizen scientists, states, tribes, communities and industry.

Sensor Performance Evaluation

EPA is evaluating commercially-available air sensor devices at its laboratories and in several field locations in the United States. The goals of these performance evaluations are to:

  • Develop a better understanding of basic sensor performance characteristics.
  • Provide results to sensor manufacturers that encourage improvements in sensor performance.
  • Communicate findings to stakeholders to improve outcomes of sensor applications.

The results of the sensor evaluations are being shared with the public through the publication of reports and journal articles. A reference guide of sensors that have been evaluated by EPA researchers is available in table format for particulate matter sensors and gas phase sensors in the online Air Sensor Toolbox.

Projects include:

  • Field Evaluation of Commercial Air Sensor Devices:
    • Air sensors are tested at EPA’s research campus in Research Triangle Park, NC, on a rolling basis, co-located with regulatory-grade monitors in a suburban environment.
    • Air sensors are co-located with regulatory-grade monitors at a monitoring site located adjacent to I-40 near Raleigh, NC, for near roadway monitoring.
    • EPA will target testing commercially-available sensors in locations affected by wildfire smoke, to understand their performance during these challenging high pollution episodes.
  • Wildland Fire Sensor Prototype Evaluation
    Air sensor prototypes submitted to the multi-agency Wildland Fire Sensor Challenge are undergoing two phases of evaluation by EPA and the U.S. Forest Service (USFS), one of the Challenge partners. Other partners are the National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and the Centers for Disease Control and Prevention (CDC).

Related Resources:

Development and Application of Air Sensor Technology

EPA is applying its expertise in air quality measurement and monitoring to develop new sensor instruments and systems that meet specific needs for monitoring air quality. These sensor devices are being tested in the laboratory and then used in field studies. Some devices are placed in portable lunch-box sized enclosures for use by citizen scientists, while others are being designed for use as stationary monitors. Still others are being developed to take into the field for specific uses such as monitoring emissions from wildland fires.   

Projects include:

  • Village Green Air Monitoring System: The Village Green Project is a flagship research project to measure real-time local air quality with an innovative solar and wind-powered system, designed and incorporated into a park bench. The air measuring benches are installed at numerous locations in the U.S. A manual and training video have been developed that offers information on how to build, operate and maintain a Village Green station.
  • AirMapper: The AirMapper is a portable air sensor that EPA researchers are developing to allow environmental conditions to be easily mapped by researchers and citizen scientists. The AirMapper is a small instrument case that can be carried or attached to a bicycle, and includes rechargeable battery power, a global positioning system (GPS), particle pollution sensor, and other sensors measuring environmental conditions (e.g., temperature, humidity). Participants can explore the various measurements collected in the touchscreen interface or through a free data explorer tool that EPA developed, called RETIGO.
  • RETIGO is a freely available web-based application, where professional or citizen researchers can import and visualize their collected environmental data. The tool is designed to be flexible and compatible with any data set that has a recorded time, location (latitude, longitude), and other measurement data.
  • Guides, manuals and other resources are developed by EPA to provide information on how air sensors can be used, what to look for in a sensor, how to collect useful data using sensors, and how to evaluate and interpret the data. One such guide is an instruction guide and macro analysis tool for citizen scientists to evaluate the performance of low-cost air sensors and interpret the data they collect to help learn about local air quality.
  • Kansas City Transportation and Local-Scale Air Quality Study: In fall 2017, the EPA launched the Kansas City Transportation and Local-Scale Air Quality Study (KC-TRAQS), to learn more about local community air quality in three neighborhoods in Kansas City, KS, that have multiple air pollution sources from highways, railways, and industry. The study will be conducted for one year and provide comprehensive air quality monitoring using three different air measurement approaches. A citizen science project is part of the study and will involve area residents and students in air measurement activities using the AirMapper system. 

Related Resources:

Research Partnerships

EPA collaborates with states, tribes, communities, industry and companies in activities to advance the development and use of sensor technologies. Research projects are conducted under research agreements with companies and other partnership opportunities.   

Projects include:

  • Aeroqual Collaboration: In November 2017, EPA signed a Cooperative Research and Development Agreement (CRADA) with Aeroqual, a New Zealand-based company specializing in the development of air quality monitoring equipment, with the goal of investigating new applications, methodologies and technologies for the low-cost measurement of outside air pollutants. 
  • PM Sensor: A Cooperative Research and Development Agreement (CRADA) with ACLIMA, a technology company in California, is providing an opportunity to investigate sensor technologies and mobile air quality monitoring.
  • Wildland Fire Sensor Challenge: EPA and five other federal agencies have announced a Wildland Fire Sensors Challenge seeking an accurate, lower-cost, and low-maintenance air quality monitoring system that can be used during a wildfire or controlled fire. The data provided by the sensor system will help federal, state, local and tribal agencies protect the health of first responders and communities affected by the smoke.

Related Resources: