# WHO scale for PM2.5?
**URL:** https://community.purpleair.com/t/who-scale-for-pm2-5/1385
**Category:** Feature Requests
**Created:** [July 26, 2022, 5:48pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385 "2022-07-26T17:48:03Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@Mark\_from\_Pittsburgh](https://community.purpleair.com/u/Mark_from_Pittsburgh)
#### Post date: [July 26, 2022, 5:48pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/1 "2022-07-26T17:48:03Z")
I believe it would be both valuable and interesting to see a PurpleAir map with a selectable layer for “WHO PM2.5” (WHO = World Health Organization) that shows green only at or below 5 micrograms/cubic meter. Not sure what yellow or red or purple colors would indicate, but maybe we could put our heads together to figure it out? Here’s some info on their air quality guidelines: [https://www.who.int/news-room/feature-stories/detail/what-are-the-who-air-quality-guidelines](https://www.who.int/news-room/feature-stories/detail/what-are-the-who-air-quality-guidelines)
Thoughts?
Mark
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### Author:  [@Louise\_E](https://community.purpleair.com/u/Louise_E)
#### Post date: [July 29, 2022, 4:55am UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/2 "2022-07-29T04:55:09Z")
Excellent idea - I would like to have that feature also.
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### Author:  [@dwhitemv](https://community.purpleair.com/u/dwhitemv)
#### Post date: [August 2, 2022, 3:10am UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/3 "2022-08-02T03:10:12Z")
The specifications you linked prescribe _annualized_ exposure, not immediate or hourly exposure. You could develop a map using PA data to plot compliance with the guideline on a yearly basis. That said, no country reporting data for 2016 (the latest WHO has published in their Air Quality Data Portal) meets the new 5 ug/m3 guideline.
There’s a list of interim targets in the guidelines you could use as a basis for a color key.
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### Author:  [@Gary](https://community.purpleair.com/u/Gary)
#### Post date: [August 25, 2022, 6:31pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/4 "2022-08-25T18:31:52Z")
The WHO 24 hour standard is 15 μg/m3 24-hour mean (see [Ambient (outdoor) air pollution](https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health)) at the 99th percentile (i.e. 3–4 exceedance days per year).
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### Author:  [@Gary](https://community.purpleair.com/u/Gary)
#### Post date: [January 22, 2023, 5:15pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/5 "2023-01-22T17:15:03Z")
How do ideas such as adding the WHO 24 hour standard as another selectable layer actually get implemented? The PurpleAir Community has a keen interest in protecting their own and their communities’ health. The WHO standards would serve to demonstrate the flaws associated with relying upon a single country’s politically established standard as opposed to understanding the actual risks of exposure to life threatening pollution (WHO’s standard).
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### Author:  [@PokAlice](https://community.purpleair.com/u/PokAlice)
#### Post date: [January 26, 2023, 12:37am UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/6 "2023-01-26T00:37:34Z")
I also agree this would be a good addition as a selectable layer.
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### Author:  [@Kieran](https://community.purpleair.com/u/Kieran)
#### Post date: [March 6, 2024, 11:28pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/7 "2024-03-06T23:28:43Z")
@Mark_from_Pittsburgh @Louise_E @dwhitemv @Gary @PokAlice
Our apologies on getting to this late. We are interested in supporting what the community wants, and could institute something like this. The question is however, what would the data layer look like? Is the idea to have breakpoints relating to the interim target levels?
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### Author:  [@Gary](https://community.purpleair.com/u/Gary)
#### Post date: [March 7, 2024, 8:34pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/8 "2024-03-07T20:34:19Z")
Using the interim targets, as break points, would provide a fairly easily understood scale. It would also serve to highlight the urgency and necessity of updating the various national ambient air quality standards to those recommended by WHO.
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### Author:  [@Gary](https://community.purpleair.com/u/Gary)
#### Post date: [March 20, 2024, 5:23pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/9 "2024-03-20T17:23:26Z")
Sobering info at [Seven countries met the WHO's air quality guidelines — and the U.S. and Canada aren't among them](https://apple.news/AmL0KkMuvQoObKqV5oHdDiQ) and an illustration why a WHO selectable ambient air quality standard is an urgent need.
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### Author:  [@Gary](https://community.purpleair.com/u/Gary)
#### Post date: [September 12, 2024, 5:38am UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/10 "2024-09-12T05:38:15Z")
Given the real time sensor data, the WHO 24 hour standard at 15 μg/m3 24-hour mean (see [Ambient (outdoor) air pollution](https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health)) at the 99th percentile (i.e. 3–4 exceedance days per year) would be more appropriate than the WHO annual standard.
Updated 9/11/24 - It has been more than a year since the suggestion to use WHO’s PM2.5 24 hour standard was suggested. But the “feature” has yet to be added. Is there work being done on this and, if so, when it is set to be launched.
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### Author:  [@Kieran](https://community.purpleair.com/u/Kieran)
#### Post date: [October 7, 2024, 11:28pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/11 "2024-10-07T23:28:02Z")
@Gary @dwhitemv @Mark_from_Pittsburgh @Louise_E @PokAlice
Our apologies for the silence on this topic. We’ve been working hard on the map, and this didn’t make it into the large update a couple of weeks ago.
However, we just released a data layer earlier today based on the WHO exposure guidelines, using interim targets as breakpoints. If you’re on the map, the data layer is listed under “Air Quality” as _WHO PM2.5 AQG and Interim Targets (µg/m3)_.
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### Author:  [@Gary](https://community.purpleair.com/u/Gary)
#### Post date: [October 8, 2024, 8:08pm UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/12 "2024-10-08T20:08:08Z")
Hi Kieran,
This is fantastic. Adding WHO’s PM2.5 exposure guidelines, using the interim targets as breakpoints, will be a meaningful step in boosting awareness of the public health threat that the current standards, in most countries, represent - especially for the young, aged, and people with compromised heart or respiratory systems.
Thank you for your work and the addition of the WHO PM 2.5 daily standard as a data layer,
Gary Shaff
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### Author:  [@Louise\_E](https://community.purpleair.com/u/Louise_E)
#### Post date: [June 18, 2025, 5:22am UTC](https://community.purpleair.com/t/who-scale-for-pm2-5/1385/13 "2025-06-18T05:22:53Z")
Thank you for this. This is my standard setting 😃