Frequently Asked Questions (FAQs)

How do I select a sensor for my personal use or for my project?

Choosing a sensor for your personal use or for a project depends on your monitoring goals and objectives. AQ-SPEC evaluates the performance of air quality sensors and does not make sensor recommendations or endorsements. To guide your sensor selection, first define your monitoring goals, objectives, performance requirements. This can be clarified by selecting what pollutants you want to measure (gas or particle pollutants), where you want to measure (indoor vs. outdoor), expected connectivity at sensing locations (Wi-Fi, Bluetooth, cellular, etc.), expected power at sensing locations (wall power or solar), and sensor measurement performance requirements (measurement error, linearity, correlation, etc.).  Also, you may want to consider the available budget for purchasing/leasing sensors and/or purchasing subscription(s) for data access/dashboard visualizations. Please visit our AQ-SPEC website (  and the various webpages (e.g., , to gather information and details about our sensor performance evaluation work in the field and in the lab, sensor cost, features, and other technical characteristics.

What is a good PM sensor?

The Air Quality Sensor Performance Evaluation Center (AQ-SPEC) at the South Coast AQMD has evaluated a large portion of the widely commercially available PM air quality sensors measuring criteria pollutants including PM2.5 and PM10 for their performances. AQ-SPEC does not endorse or recommend air quality sensors. Please visit the PM sensors summary table at and also the individual sensor product pages at to gather more information about the various sensors that have been evaluated in the AQ-SPEC program.

I am considering a sensor for purchase, but AQ-SPEC has not yet evaluated the sensor.

Please confirm by visiting our AQ-SPEC website ( and the various webpages (e.g., , to ensure the sensor has not yet been evaluated. If so, please send AQ-SPEC a note to and provide the sensor manufacturer and model information.

I would like to purchase a sensor, can you send me a quote to purchase?

AQ-SPEC is a program that evaluates the performance of air quality sensors. AQ-SPEC does not sell air quality sensors. Please reach out to the company manufacturing the sensor for quotations.

How accurate are these sensors?

All sensors tested, including PM and gas sensors, are evaluated side by side with EPA approved federal equivalent method (FEM)/ federal reference method (FRM) instruments. Air quality sensors are compared to the FEM/FRM instruments to evaluate their performances and accuracy with regards to reference-grade instrumentation.

What is the lifetime of the sensors?

Sensor lifetime has not been evaluated by AQ-SPEC. Lifetime of sensors depends on many factors including but not limited to: the type of sensing material, usage of sensor and operating/environmental conditions. Some manufactures have specified the lifetime of the sensors. Please visit for more detailed specifications about various sensors tested by AQ-SPEC.

Which sensors does AQ-SPEC recommend?

AQ-SPEC does not endorse or recommend air quality sensors. Please visit the following pages to gain more information about sensor performance in AQ-SPEC evaluations that might help you make an informed purchasing decision:

Are there certifications for the sensors?

No certifications currently exist for consumer-grade, research-grade monitors. There is U.S. EPA approved designation (i.e., Federal Reference Method, Federal Equivalent Method) for regulatory-grade monitors.

Are there evaluations for air purifiers?

AQ-SPEC does not evaluate air purifiers. Please visit the ARB website for more information at:

Does SCAQMD/AQ-SPEC lend sensors to interested entities?

AQ-SPEC will soon expand its pilot sensor library program using funding from a U.S. EPA American Rescue Plan grant. For further information please contact Inclusion of a product in the sensor library program does not constitute an endorsement of that product.

Are there certified sensors?

At this time, no program exists to certify the performance of sensors. The US EPA is developing a sensor certification program with a 5-year timeline. In California, air quality districts and CARB are discussing the possibility to develop a performance verification program for PM2.5, O3 and possibly NO2 sensors with a 1-year time frame.

Can my personal sensor be certified by AQ-SPEC? Can my personal sensor be calibrated by AQ-SPEC? Can my sensor performance be verified by AQ-SPEC?

AQ-SPEC currently evaluates the performance of the sensor and does not certify air quality sensors. AQ-SPEC evaluates the performance of new widely commercially available sensors. AQ-SPEC does not verify the performance of individual or personal sensors.

Do you have any plans to measure the drift over a number of years?

AQ-SPEC currently does not evaluate sensor lifetime or drift in AQ-SPEC sensor evaluations. AQ-SPEC is operating a number of sensor networks that have been deployed for extended periods of time. These deployments provide the opportunity to examine sensor drift by sensor project. We are currently preparing a manuscript where we will be commenting on this issue. In the near future, we will start looking at sensor drift in our laboratory chamber experiments at the South Coast AQMD.

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