If your sensor is “private”, you won’t be able to find it on the map. We plan to support private sensors in the future, but in the meantime, let us know you’re looking forward to adding your private sensor by emailing support. If this is a popular request, we’ll prioritize it.

The Purple Air website will show you the most up-to-date values reported by the sensor, however Purple Air asks that we limit how often we look up the value. This means the sensor reading shown in the app could be (up to) 10 minutes older than the reading shown on the map.

If you need to know the most up-to-date sensor reading, you can quickly open the Purple Air website by tapping the sensor in the list, and selecting the “Open Map” button, or using the menu button on the sensor page.

Alternatively, the app configuration might not match the Purple Air website. See My configuration does not match for more information.

There’s a few reasons why the AQI reported by a Purple Air sensor does not match a local reporting agency.

1. Different air quality reporting schemes depend on many pollutant types, however Purple Air sensors only measure particulate matter. If the air quality measurement used by the local reporting agency is computed using a component not measured by the Purple Air sensor, the results will not match.

   For example, the US EPA AQI calculates a per-pollutant AQI for each of ozone, particulate matter (including PM_2.5 and PM₁₀), CO, NO₂, SO₂, and uses the worst value as the overall AQI. For a PM_2.5 AQI of 30, and an ozone AQI of 55, Purple Air sensors will report AQI of 30 (Good), while a reporting agency would report 55 (Moderate).

2. The physical location of a sensor affects the reading. A sensor on top of a building may report a different value than a sensor at ground level, or a sensor a block away.

3. Purple Air reports data measured in real-time, or as an average over the recent data. Reporting agencies may be reporting an average over a different time range, or use some type of forecasting model.

4. Different reporting agencies (US EPA, BCCDC, etc.) use different formulas to calculate their respective air quality measurements. Make sure you are using the same reporting system as your local agency.

Purple Air asks that we limit how often we look up sensor readings. If a sensor reading passed an alert threshold, but quickly returned to the previous threshold range, you may not an alert.

If you are using the real-time sensor reading, you should consider using an “average” reading (or if you are already using an average, consider using a longer averaging period) and updating the threshold. This will reduce the effect of transient spikes (or drops) to sensor readings, allowing you to set the alert threshold lower, or reducing the “noise”.

Alternatively, the app configuration might not match the Purple Air website. See My configuration does not match for more information.

While it’s important to be aware of changing conditions, it’s natural to start ignoring notifications when there are too many. If the notifications are being ignored, then you may miss an important one. (A version of the boy who cried wolf!)

A noisy sensor can be a hard problem to deal with. There is no solution that will work for everybody. Here are some ideas you might try.

Adjusting the threshold

Try setting your alert thresholds for when you intend to take action. For example, “when the air quality is worse 100, bring the kids inside, when the air quality is worse than 150, close the windows”, so set an alert thresholds for 100, and 150.

Try a (longer) average reading

If you are using the real-time sensor reading, you should consider using an “averaging period¹” (or if you are already using an average, consider using a longer period). This will “smooth out” transient spikes (or drops) to sensor readings, allowing you to set a lower alert threshold, and/or reducing the “noise”.

Temporarily mute a sensor

You can temporarily mute a sensor. On the detail page for the sensor, in the menu, select “Mute alerts”, and set a duration to mute notifications.

If you muted a sensor, it will show a “mute” icon in the sensor list. You can see when the sensor will automatically unmute on the sensor details page. If you want to unmute the sensor now (before it is scheduled to unmute), you can do that from the sensor details page.

You may have different configurations in the app, compared to the Purple Air website. If this happens, the sensor reading shown on the Purple Air website might match what is shown in the app.

Here are some things to check:

• Different conversion factor (e.g. US EPA conversion vs No conversion)
• Sensor reading type (e.g. AQI vs PM 2.5)
• Different data aggregation setting (e.g. real-time vs 10min average),

We periodically check the sensors you are following to make sure they are reporting accurate values. If the sensor accuracy is low. Sensors with low accuracy should not be relied on to report correct particle measurements or AQI.

If you own/manage the sensor, you can check the PurpleAir troubleshooting guide for help.

You can request a copy of your data by emailing support.

If you wish to delete your account, you can do so directly from the app in “account settings”.

If you encounter a problem deleting your account, or need help, please email support for assistance.

A different Play Store account manages my subscription

If your active Play Store account (open Play Store and select your profile photo in the top right to check the active account) is different from the one used to subscribe, then you will not be able to manage the subscription. To manage the subscription, you can change the active account in the Play store, then restart the app.

Play Store account is already associated with a different user

This means a different AQ Alert account has already subscribed using the currently active Play Store account. To subscribe, you can change the active account in the Play store.

If you need to update the AQ Alert account associated with the Play Store subscription, please email support

Device cannot currently access the available subscription options, or Subscription information currently unavailable

If your device has the Play Store app, this is likely a temporary issue. Try again in a few minutes. If the issue does not go away, please email support.

If your device does not have the Play Store app, you will not be able to manage the subscription. You must log in to an Android device with Play Store access to add or update subscription. You can always cancel a subscription using the Play Store website.