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1. I see a red circle surrounded by green circles. Why is that?

The sensor could be experiencing pollution from a nearby source, such as a fire pit or chimney. The sensor could also be malfunctioning. While we try to remove data from malfunctioning sensors through our QC process, it is not perfect. Occasionally some low quality data will get through. One thing you can do to check is to look at the minute data on the “Instant” view. If you see a lot of spikes or really high values for a long time, then that sensor is probably malfunctioning. If that is your sensor, try to clean it out with some canned air.

2. Why are the Health and Instant views different?

The Health view is an estimate using averaged particle levels. This gives a better estimate of your health impact that instant air quality levels.  The Health view is updated once an hour. The Instant view is minute data and is updated once a minute, though it may be up to 10 minutes behind the current time. Sites can experience much higher or lower particle levels for a few minutes than the level shown for their average in the Health view. Use the Health view to determine the effect of the pollution on your health and what actions you should take to protect your health. Use the Instant view to see what the particle level is right now. The Instant view can be very useful when conditions are changing rapidly, such as during a wildfire smoke event.  However, for other events, the Instant view may be short-term in nature, and you should check back to see if levels have improved.

3. What does the color scale mean?

The color scale is the Air Quality Index (AQI) developed by the US EPA. You can learn more about it here. The AQI reflects health studies that show that your pollution exposure over an entire day matters most.  However, the AQI colors are used for both the Health and Instant views. This was chosen due to the familiarity with the AQI. The minute data shown in the Instant view does not have a health effect or recommendation associated with its AQI colors. This is because exposure to moderate pollution (yellow AQI) for a whole day is worse than being exposed for just one minute. If you want to know about how the pollution can be affecting your health, use the Health view.

4. What can I use the Health view for?

Use the Health view to determine the effect of air pollution on your health. Click a circle (Purple Air) or star (Agency monitor) to see a graph of pollution levels at that location. Then click on Impact and scroll over the thumbs to see what actions you should take to protect your health.

5. What can I use the Instant view for?

Use the Instant view to see what the particle level is right now. Click a circle (Purple Air) or star (Agency monitor) to see a graph of pollution levels at that location. The Instant view can be very useful when conditions are changing rapidly, such as during a wildfire smoke event.  If you see high levels for an unknown reason, you may want to check back again and see if it was just a short-term spike in pollution (for example someone smoking a cigarette near the monitor).

6. Why does your map look different from the map at purpleair.com?

Sensors on purpleair.com are not calibrated by default. There is a drop down menu to apply a limited number of calibration equations, however they are not specific to our region. The Agency sensor map calibrates all of the sensors to nearby agency monitors, which is a more accurate way to do calibration.

7. Can I put a sensor on your map?

Sure! Any Purple Air that has its data set to Public will be automatically added to the sensor map.