Air Quality Sensors

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Air sensors are lower-cost, portable devices that measure air pollution. These sensors are available to anyone and typically cost between $100 and $2,500 – a fraction of the cost of our regulatory air monitors. 

Air sensors can estimate a variety of pollutants including: dust, fine particulate matter, carbon dioxide, carbon monoxide, ozone, nitrogen oxide, and many others. 

Although air sensors are less expensive than a regulatory air monitor, they are also less accurate. The monitors that report to our website are built and operated according to rigorous air monitoring regulations determined by the Environmental Protection Agency (EPA), and they provide high-quality data. 

But air sensors can be very useful. This is particularly true for fine particle pollution, where a network of 800+ sensors across our region provide local information. These sensors can help answer questions about local air quality, such as: 

  • How does air quality near my home compare to other neighborhoods and areas? 
  • Is air quality in my neighborhood better during the summer or winter? Day or night?

Air Sensor Lending Program

Have an air quality question that would benefit from an air sensor? Are you an educator who wants to teach kids about air quality? We now have a limited number of air sensors to loan to community groups, educators, and individuals.   

Please fill out the form to apply for a sensor loan. Applications are limited to King, Kitsap, Pierce, and Snohomish Counties. 

We review these applications quarterly, and will get back to you on status of your application after our next review. The applications are scored based on priority agency locations (see our overburdened community work), project scope, relevance of air sensors to answer your question, and including education and outreach. Project approval is also dependent on the availability of agency staff and resources. 

Note: Air sensors are intended to be educational and are non-regulatory. This means that they cannot be used for permitting, compliance, policy, or interpretation of health effects. The data from these sensors are not owned by PSCAA and we are not responsible for their use or misuse. 

Just returned your sensors? Email us with feedback on the process and tell us what you learned! 

To download your Purple Air data or create a report with sensor data try the Air Sensor Dashboard. 

  1. How do I choose a sensor?
  2. I have an air sensor, now what?
  3. How can I check if my sensor is working properly?
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Purple Air – Understanding Your Data

One of the most popular air sensors is Purple Air. Many people use Purple Air sensors to learn about fine particle pollution in their area. 

Raw Purple Air data are about two times higher than the real values during an air pollution event such as wildfire smoke. We know this from placing Purple Air sensors at our regulatory monitors and comparing measurements. 

There are two important considerations when looking at Purple Air data to ensure the data is accurate: 

  • The data need to be calibrated.
  • The data need to be in the right scale and time average.

The green-to-maroon color scheme known as the ‘air quality index’ or AQI – is only valid for 24-hour data. This is because it is based on health studies that used a daily pollution value. If you want to use Purple Air’s data for health recommendations make sure you are looking at a 24-hour average or a 24-hour estimate (known as the NowCast). 

If you want to know what is happening right now, then look at the latest or real-time values.  These may be in the same green-maroon color scheme, but the AQI health recommendations don’t apply to real-time data.  Even so, real-time data can be invaluable during a pollution event such as wildfire smoke. 

Here are three ways to view calibrated Purple Air data: Purple Air

  • Our Sensor Map
    • Calibrated and quality-controlled Purple Air data.
    • Health tab shows 24-hour estimate, Instant tab shows real-time data.
  • The EPA Fire and Smoke Map
    • Calibrated and quality-controlled Purple Air data.
    • The default view is a 24-hour estimate.  You can see real-time data for a single site by clicking on the site and scrolling through the graphs in the popup.
    • This map is particularly helpful during wildfire smoke events since it has “smoke polygons” – shaded parts of the map that indicate where smoke is thickest.
  • The Purple Air Map
    • Uncalibrated unless you click the Settings icon in the top left and change the “Apply conversion” dropdown to “US EPA”.
      • Note: The links below will show calibrated data since that setting can be stored in the link itself. 
    • Not quality-controlled
    • Daily and real-time data