# Canadian AHQI question

**URL:** <https://community.purpleair.com/t/canadian-ahqi-question/5510>\
**Category:** General\
**Created:** [July 11, 2023, 7:18pm UTC](https://community.purpleair.com/t/canadian-ahqi-question/5510 "2023-07-11T19:18:07Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Loulleyn](https://avatars.discourse-cdn.com/v4/letter/l/4af34b/32.png) [@Loulleyn](https://community.purpleair.com/u/Loulleyn)\
**Post date:** [July 11, 2023, 7:18pm UTC](https://community.purpleair.com/t/canadian-ahqi-question/5510/1 "2023-07-11T19:18:07Z")

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Hello,

I live in Kamloops, BC. On days that looks smoky I go to Purple Air as well as the Canadian Government’s AHQI website to check the air quality readings.  
Lately, today included, it’s smoky outside. The air is tinted orange and it smells like a campfire everywhere outside.  
When I look at Purple Air today it’s been reading (so far) at 1-3, low risk. What I’m seeing and smelling outside doesn’t seem to match.  
On Purple Air’s live map when I change it to another set of data like the US EPA, or the Australian PM 2.5 it’s reading as much higher and more dangerous levels.

What’s going on?

Thanks for your time

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**Author:** ![Sleepypup](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@Sleepypup](https://community.purpleair.com/u/Sleepypup)\
**Post date:** [August 19, 2023, 3:35pm UTC](https://community.purpleair.com/t/canadian-ahqi-question/5510/3 "2023-08-19T15:35:34Z")

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Rach. I had the same question living in Regina, SK. There are a couple of reasons the PA map calculation of the Cdn AQHI does not seem to match up with what our official agency Environment Cda reports. The AQHI is calculated based on the **combined** effect of 3 components (PM2.5, Ground Level Ozone, Nitrogen Dioxide). See [Air Quality Health Index (Canada) - Wikipedia](https://en.wikipedia.org/wiki/Air_Quality_Health_Index_(Canada)). The PA sensors only measure PM and that is all the PA map is using to calculated the AQHI. The second difference is that many provinces including BC/SK also use a variation of the AQHI they call AQHI-Plus during the summer months when forest fire smoke is the dominate AQ concern. That formula is much simpler. Wildfire Season AQHI-Plus = ceiling value (the closest integer greater than or equal to a given number) of the 1-hour PM2.5 concentration divided by 10. I believe BC like SK use the AQHI+ when the PM2.5 reaches 51 ug/m3. Therefore PM2.5=51 will be reported as AQHI 6…61 would be 7 and so on. See [https://www.tandfonline.com/doi/full/10.1080/10962247.2020.1797927](https://www.tandfonline.com/doi/full/10.1080/10962247.2020.1797927) for studies from your province.

I prefer to switch the map to show me Raw PM2.5 concentration and convert using the AQHI+ formula. I also use the ALT CF=3 conversion factor as the PA devices mostly over estimate PM and I have found that setting more closely matches official sources. Play around with the different settings. Lots of good data to play with.

One other good way to compare the PA devices to official sensors in Canada is to use this [AQmap (EN)](https://cyclone.unbc.ca/aqmap/). Originates in your province as well. It shows PM2.5 only but a good resources to see how PA stacks up against official sensors.

Hope this helps.  
Dean

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**Author:** ![Nick\_PurpleAir](https://sea2.discourse-cdn.com/flex020/user_avatar/community.purpleair.com/nick_purpleair/32/3055_2.png) [@Nick\_PurpleAir](https://community.purpleair.com/u/Nick_PurpleAir)\
**Post date:** [September 15, 2023, 5:03pm UTC](https://community.purpleair.com/t/canadian-ahqi-question/5510/4 "2023-09-15T17:03:41Z")

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This is excellent information!