# FAQ **URL:** https://community.purpleair.com/c/faq/27.md [Latest](https://community.purpleair.com/latest.md) · [Categories](https://community.purpleair.com/categories.md) --- ## [PurpleAir FAQ](https://community.purpleair.com/t/purpleair-faq/3682)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [March 1, 2023, 9:18pm UTC](https://community.purpleair.com/t/purpleair-faq/3682 "2023-03-01T21:18:00Z")
Here is a selection of commonly asked questions. But these are not all questions or answers. Clicking on any one of the questions will take you to that question in our community forum. From there, you can search for more… --- ## [About the FAQ category](https://community.purpleair.com/t/about-the-faq-category/807)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 1\ **Last updated:** [December 29, 2022, 1:55pm UTC](https://community.purpleair.com/t/about-the-faq-category/807 "2022-12-29T13:55:22Z")
Here, you can find frequently asked questions about PurpleAir’s sensors, map, and data. Feel free to browse. If you have a question thats not here, please ask! --- ## [Does PurpleAir have an app?](https://community.purpleair.com/t/does-purpleair-have-an-app/987)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 14\ **Last updated:** [July 29, 2026, 6:04pm UTC](https://community.purpleair.com/t/does-purpleair-have-an-app/987 "2026-07-29T18:04:37Z")
PurpleAir’s Real-Time Map is a Progressive Web App (PWA) which can be installed on Android, IOS and desktop devices. Look for the “Add to Desktop” options on your phone or the install button in your web browser. Below a… --- ## [What hostnames and ports do PurpleAir sensors use?](https://community.purpleair.com/t/what-hostnames-and-ports-do-purpleair-sensors-use/4277)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 2\ **Last updated:** [November 7, 2025, 10:36pm UTC](https://community.purpleair.com/t/what-hostnames-and-ports-do-purpleair-sensors-use/4277 "2025-11-07T22:36:16Z")
PurpleAir sensors will only communicate with the following fully qualified domain (FQDN) hostnames: http://www.purpleair.com http://api.purpleair.com update.purpleair.com sensors-ingest.wunderground.com pool.ntp.org ww… --- ## [Can I add a mesh screen to my sensor to keep out bugs and critters?](https://community.purpleair.com/t/can-i-add-a-mesh-screen-to-my-sensor-to-keep-out-bugs-and-critters/845)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 4, 2022, 6:44pm UTC](https://community.purpleair.com/t/can-i-add-a-mesh-screen-to-my-sensor-to-keep-out-bugs-and-critters/845 "2022-06-04T18:44:03Z")
We don’t recommend covering the base of your PurpleAir sensor with any material. The sensor is designed to draw in ambient air so the laser counters can measure the particulate matter suspended in it. If the base is cove… --- ## [Why isn't my map location being saved?](https://community.purpleair.com/t/why-isnt-my-map-location-being-saved/21815)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [July 24, 2025, 10:41pm UTC](https://community.purpleair.com/t/why-isnt-my-map-location-being-saved/21815 "2025-07-24T22:41:00Z")
We recently cleared cookie consent data for the website and the PWA (app), which may cause the map or PWA to load fully-zoomed out, instead of saving your last visited location, as it should do normally. To have the map … --- ## [Can I calibrate my PurpleAir sensor?](https://community.purpleair.com/t/can-i-calibrate-my-purpleair-sensor/844)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 4, 2022, 6:43pm UTC](https://community.purpleair.com/t/can-i-calibrate-my-purpleair-sensor/844 "2022-06-04T18:43:15Z")
Factory Calibration & Lifetime Limitations PurpleAir sensors use Plantower laser counters that are factory-calibrated before shipping. There is no method for post-production calibration of the laser counters—you can’t a… --- ## [Can I calibrate the temperature sensor](https://community.purpleair.com/t/can-i-calibrate-the-temperature-sensor/21762)
**Author:** [@Amanda\_Hawkins](https://community.purpleair.com/u/Amanda_Hawkins)\ **Replies:** 0\ **Last updated:** [July 13, 2025, 5:19pm UTC](https://community.purpleair.com/t/can-i-calibrate-the-temperature-sensor/21762 "2025-07-13T17:19:27Z")
The temperature sensor in PurpleAir devices comes pre-calibrated by the manufacturer, and currently, there is no method for manually recalibrating it. However, if you’re seeing temperature readings that seem higher than … --- ## [How do the PurpleAir sensors differ, and can I mount them indoors OR outdoors?](https://community.purpleair.com/t/how-do-the-purpleair-sensors-differ-and-can-i-mount-them-indoors-or-outdoors/822)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 1\ **Last updated:** [June 9, 2025, 9:47pm UTC](https://community.purpleair.com/t/how-do-the-purpleair-sensors-differ-and-can-i-mount-them-indoors-or-outdoors/822 "2025-06-09T21:47:18Z")
Meant for indoor use only, the PA-I-Indoor sensor incorporates a full-color LED allowing the device to glow the color of the current air quality (green, yellow, orange, red, purple, and maroon). Sporting a simple design … --- ## [How Do I Know if my Sensor is Working Properly?](https://community.purpleair.com/t/how-do-i-know-if-my-sensor-is-working-properly/12148)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [April 11, 2025, 10:30pm UTC](https://community.purpleair.com/t/how-do-i-know-if-my-sensor-is-working-properly/12148 "2025-04-11T22:30:15Z")
This article covers simple checks and steps you can take to make sure your PurpleAir sensor is working as it should. These include using the PurpleAir map, checking your sensor’s data, and performing a few easy tests. U… --- ## [Can I set my PurpleAir sensor to private, and how do I view a private sensor on the map?](https://community.purpleair.com/t/can-i-set-my-purpleair-sensor-to-private-and-how-do-i-view-a-private-sensor-on-the-map/819)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 9\ **Last updated:** [February 21, 2025, 11:00pm UTC](https://community.purpleair.com/t/can-i-set-my-purpleair-sensor-to-private-and-how-do-i-view-a-private-sensor-on-the-map/819 "2025-02-21T23:00:40Z")
Setting Your Sensor to Private When registering your PurpleAir sensor, you have the option to designate it as either public or private with the Visibility option. Public Sensors: Visible to all users on the PurpleAi… --- ## [Purchasing](https://community.purpleair.com/t/purchasing/10922)
**Author:** [@Amanda\_Hawkins](https://community.purpleair.com/u/Amanda_Hawkins)\ **Replies:** 0\ **Last updated:** [December 13, 2024, 10:29pm UTC](https://community.purpleair.com/t/purchasing/10922 "2024-12-13T22:29:23Z")
Welcome to our purchasing page. You will find most information on common questions from tax-exempt to doing a purchase order. Let us know if you have any questions. Tax-Exempt and W9 Use this link to take you to our pag… --- ## [Can I Take my Sensor on the Road?](https://community.purpleair.com/t/can-i-take-my-sensor-on-the-road/10954)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [December 18, 2024, 9:33pm UTC](https://community.purpleair.com/t/can-i-take-my-sensor-on-the-road/10954 "2024-12-18T21:33:00Z")
Yes, you can definitely take your sensor on the road. However, we do have some recommendations. PurpleAir sensors have been tested and evaluated for stationary use, which is how we recommend operating them. The sensor… --- ## [Tax Exempt](https://community.purpleair.com/t/tax-exempt/10915)
**Author:** [@Amanda\_Hawkins](https://community.purpleair.com/u/Amanda_Hawkins)\ **Replies:** 0\ **Last updated:** [December 13, 2024, 1:22am UTC](https://community.purpleair.com/t/tax-exempt/10915 "2024-12-13T01:22:52Z")
If you are eligible for tax exemption, please follow the steps below to ensure your status is applied to your profile before making a purchase: 1. Complete the Required Steps: Follow the detailed instructions here. Upl… --- ## [Purchase Orders](https://community.purpleair.com/t/purchase-orders/1634)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [August 15, 2022, 6:11pm UTC](https://community.purpleair.com/t/purchase-orders/1634 "2022-08-15T18:11:26Z")
Does PurpleAir accept Purchase Orders? Yes, we do! To place an order using a purchase order (PO), please email billing@purpleair.com to request an invoice. Be sure to include the billing and shipping information, along w… --- ## [Payment Methods](https://community.purpleair.com/t/payment-methods/795)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 2, 2022, 6:50pm UTC](https://community.purpleair.com/t/payment-methods/795 "2022-06-02T18:50:17Z")
Make a purchase with PurpleAir using several accepted methods of payment. All prices are listed in U.S. dollars. Credit Cards PurpleAir accepts MasterCard, Visa, American Express, and Discover credit cards. Shop Pay Pa… --- ## [How to Request a Refund](https://community.purpleair.com/t/how-to-request-a-refund/139)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [October 20, 2021, 9:58pm UTC](https://community.purpleair.com/t/how-to-request-a-refund/139 "2021-10-20T21:58:17Z")
To request a refund, notify PurpleAir by emailing billing@purpleair.com within 30 days of the ship date. In your message include the following; (1) order number, (2) Device ID of the sensor(s), and (3) a brief descripti… --- ## [What does downgraded mean on the graph?](https://community.purpleair.com/t/what-does-downgraded-mean-on-the-graph/821)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 3, 2022, 4:29pm UTC](https://community.purpleair.com/t/what-does-downgraded-mean-on-the-graph/821 "2022-06-03T16:29:44Z")
PurpleAir PA-II and PA-II-SD sensors contain two laser particle counters that measure real-time particulate matter and report as Channel A and Channel B. If one of the channels appears to be reading improperly, it can b… --- ## [Indoor Sources of Particulate Matter (PM)](https://community.purpleair.com/t/indoor-sources-of-particulate-matter-pm/8778)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 4, 2024, 6:13pm UTC](https://community.purpleair.com/t/indoor-sources-of-particulate-matter-pm/8778 "2024-06-04T18:13:13Z")
Indoor PM (particulate matter) comes from a combination of indoor sources and outdoor infiltration. Indoor sources of PM can be emitted through a number of common activities. At the same time, outdoor infiltration occurs… --- ## [What do I do With a Replacement Sensor?](https://community.purpleair.com/t/what-do-i-do-with-a-replacement-sensor/10347)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [September 25, 2024, 10:04pm UTC](https://community.purpleair.com/t/what-do-i-do-with-a-replacement-sensor/10347 "2024-09-25T22:04:35Z")
If you get a new sensor because an old one has failed, there is nothing special you have to do. There isn’t a way to link a new sensor with an old sensor’s map dot. So all you have to do is register the new sensor in wha… --- ## [How do I match PurpleAir's Map with AirNow's Fire and Smoke Map?](https://community.purpleair.com/t/how-do-i-match-purpleairs-map-with-airnows-fire-and-smoke-map/5760)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [July 26, 2023, 6:14pm UTC](https://community.purpleair.com/t/how-do-i-match-purpleairs-map-with-airnows-fire-and-smoke-map/5760 "2023-07-26T18:14:26Z")
The Fire and Smoke Map has an FAQ document which details the difference between the AirNow Fire and Smoke Map and the PurpleAir map on page 7. If you have visited AirNow’s Fire and Smoke Map, you may have noticed that… --- ## [Can I add data from non-PurpleAir sensors?](https://community.purpleair.com/t/can-i-add-data-from-non-purpleair-sensors/820)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 3, 2022, 4:28pm UTC](https://community.purpleair.com/t/can-i-add-data-from-non-purpleair-sensors/820 "2022-06-03T16:28:53Z")
At this time, only PurpleAir sensors can report to the PurpleAir Map. --- ## [Why are my sensor's LEDs blue?](https://community.purpleair.com/t/why-are-my-sensors-leds-blue/7708)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [January 12, 2024, 12:18am UTC](https://community.purpleair.com/t/why-are-my-sensors-leds-blue/7708 "2024-01-12T00:18:00Z")
PurpleAir sensors with an AQI LED indicator (the Flex, Zen, and Touch) will illuminate blue when checking for firmware updates. This happens immediately after the sensor powers on, and every hour after that. View the pic… --- ## [LCS vs FRM/FEM](https://community.purpleair.com/t/lcs-vs-frm-fem/9017)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 27, 2024, 9:05pm UTC](https://community.purpleair.com/t/lcs-vs-frm-fem/9017 "2024-06-27T21:05:00Z")
What is a Federal Reference Method? Federal Reference Method (FRM) “monitors collect particulate samples on filters, which are later weighed and analyzed in a laboratory. Because of this two-step process, PM2.5 air quali… --- ## [How Do I Calculate My API Call's Point Cost](https://community.purpleair.com/t/how-do-i-calculate-my-api-calls-point-cost/8736)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [May 29, 2024, 9:35pm UTC](https://community.purpleair.com/t/how-do-i-calculate-my-api-calls-point-cost/8736 "2024-05-29T21:35:08Z")
This article is related to the PurpleAir API. If you are unfamiliar with it, check out our API Landing Page to get started. There are two main ways to determine the number of points an API call might require: calculat… --- ## [Does SD Card Data Get Uploaded to the Map?](https://community.purpleair.com/t/does-sd-card-data-get-uploaded-to-the-map/8923)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 19, 2024, 11:43pm UTC](https://community.purpleair.com/t/does-sd-card-data-get-uploaded-to-the-map/8923 "2024-06-19T23:43:32Z")
No, data recorded to microSD cards is never uploaded to PurpleAir and does not appear on the map. If a sensor loses internet connection, data may still be recorded to its microSD card, however, that data will not be on t… --- ## [How do I view Outdoor/Indoor/My PurpleAir sensors?](https://community.purpleair.com/t/how-do-i-view-outdoor-indoor-my-purpleair-sensors/816)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 0\ **Last updated:** [June 3, 2022, 4:18pm UTC](https://community.purpleair.com/t/how-do-i-view-outdoor-indoor-my-purpleair-sensors/816 "2022-06-03T16:18:30Z")
In the map’s configuration menu, there are checkboxes for “Outside Sensors”, “Inside Sensors”, and “Show My Sensors.” Check the boxes of the sensors you want to be visible on the PurpleAir map. Outdoor sensor icons have … --- ## [Should I use the conversion factors on the PurpleAir map?](https://community.purpleair.com/t/should-i-use-the-conversion-factors-on-the-purpleair-map/815)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 4\ **Last updated:** [March 14, 2024, 2:23am UTC](https://community.purpleair.com/t/should-i-use-the-conversion-factors-on-the-purpleair-map/815 "2024-03-14T02:23:17Z")
The default setting on the PurpleAir map is the US EPA PM2.5 AQI calculated from the raw PM2.5 concentration reported by PurpleAir sensors. More information is available here: PurpleAir Data Calibrations Purple Air uses… --- ## [How do I download sensor data?](https://community.purpleair.com/t/how-do-i-download-sensor-data/4650)
**Author:** [@PurpleAir](https://community.purpleair.com/u/PurpleAir)\ **Replies:** 3\ **Last updated:** [March 4, 2024, 4:25am UTC](https://community.purpleair.com/t/how-do-i-download-sensor-data/4650 "2024-03-04T04:25:04Z")
Map Download Data that appears in the graph on the PurpleAir map can be downloaded. Learn more here: Download Map Graph Data. PurpleAir API An API is a tool that allows you to access data through code. The PurpleAir API… --- ## [My Zen LED's have gone dark. Did they fail?](https://community.purpleair.com/t/my-zen-leds-have-gone-dark-did-they-fail/4097)
**Author:** [@Adrian](https://community.purpleair.com/u/Adrian)\ **Replies:** 8\ **Last updated:** [December 31, 2023, 12:49am UTC](https://community.purpleair.com/t/my-zen-leds-have-gone-dark-did-they-fail/4097 "2023-12-31T00:49:56Z")
Zen (and Touch) sensors contain a new “Tap” feature to adjust the brightness of the LED’s. Double tapping the sensor will cycle the LED’s through the different brightness settings, so try double tapping the sensor and yo… [Next page](https://community.purpleair.com/c/faq/27.md?page=1)