In response to the growing development and availability of low-cost air monitoring sensor technology, the District has established the Technical Evaluation of Sensor Technology (TEST) Program to evaluate the performance of a variety of low-cost sensors in the San Joaquin Valley. Performance results and related information will be made publically available on a periodic basis, with the goal of enhancing the understanding of the potential use and limitations of new sensor technologies.
Air monitoring sensor technology has been developing at a rapid pace over recent years, increasing the number of analyzers that the general public can use to measure particulate matter, ozone, or other pollutants at their own home or business. In addition, these sensor technologies are becoming more affordable, making them more accessible to Valley citizens who wish to conduct personal air monitoring. As a result, there are now more options for personal air monitoring equipment than ever before.
However, since low-cost sensor technologies are equipped with low-precision components and do not follow strict maintenance and calibration guidelines that regulatory-grade monitors must adhere to, over time the accuracy of low-cost sensor data can diminish and drift from known performance standards. Due to this, the interpretation and use of data from low-cost sensors can cause confusion and mislead Valley residents regarding the status of current air quality conditions. To improve clarity on this issue, the need to evaluate and provide information on the performance and limitations of low-cost sensor technology will be key as sensor technology continues to advance and grow in its use.
In addition to providing the results of low-cost sensor performance evaluations, the development of education materials focused on the proper sensor placement, operation, and interpretation of collected data will also be valuable as low-cost sensors continue to be used for various monitoring projects. The District will also seek to provide technical and monitoring assistance to local community groups and businesses as they develop and implement a number of community air monitoring projects in the coming years.
The PurpleAir PA-II sensor uses an optical laser-based particle counting methodology to estimate the concentration of PM1, PM2.5, and PM10. The PA-II sensor also measures temperature, pressure, and relative humidity.
The following documents summarize the performance of this sensor by quarter:
The Clarity sensor uses optical laser-based particle counting methodology to estimate the concentration of PM2.5. The Clarity sensor also measures temperature and relative humidity.
The following documents summarize the performance of this sensor by quarter:
The APIS sensor uses an active flow and sample control system that measures CO, NO, NO2, and O3. The APIS sensor also measures temperature, pressure, and relative humidity.
The following documents summarize the performance of this sensor by quarter:
Using interchangeable sensor heads, the Aeroqual sensor is capable of measuring particulates or 17 different gases. Only ozone (O3) is measured for this analysis using the 0-500 ppb range sensor head. The ozone sensor head uses an active flow and sample control system using Gas Sensitive Semiconductor (GSS) technology. The Aeroqual sensor also measures temperature and relative humidity.
The following documents summarize the performance of this sensor by quarter:
The Dylos sensor uses optical laser-based particle counting methodology to estimate the concentration of PM2.5 and PM10. The Dylos sensor counts and measures the size of the individual particles to calculate the mass concentration of the particles.
The following documents summarize the performance of this sensor by quarter:
The AirBeam sensor measures particulate matter (PM1, PM2.5, and PM10) using a light scattering method. As air is drawn through a sensing chamber, light from a laser scatters off of particles in the air stream. A detector then registers and converts the light scatter into a measurement which estimates the number of particles in the airstream. The AirBeam sensor also measures temperature and relative humidity.
The following documents summarize the performance of this sensor by quarter:
As they are developed, the District will make available here educational materials regarding the use of low-cost air monitoring sensors, guidance documents on how these sensors should be placed, operated, and how their data should be interpreted and used, and links to outside resources.
