Brutkey

Marielle Quinton
@mariellequinton@ottawa.place

So, Purple Air and IQAir are both giving US PM 2.5 numbers in the fifties, which is yellow/moderate. Normally this would mean Environment Canada would show a ~2 on the AQHI because the index thinks ozone is more dangerous than small particulates, which is just wrong when it comes to forest fire smoke. But it's currently showing 4 (yellow/moderate) which is similar to the PM 2.5 and probably fairly correct. I wonder why and if something changed (did they finally update the index)? Or is there something else terrible going on?

TomWilsonYEG
@CTHW@mstdn.ca

@mariellequinton@ottawa.place

To arrive at the Canadian AQI divide pm 2.5 by 10 and round up …
So a pm 2.5 in the 50's would equate to an AQI of 6
So far it's worked well for my detector & Purple Air.
Purple air has a woodsmoke conversion as well but I'm not sure what it does.

Marielle Quinton
@mariellequinton@ottawa.place

@CTHW@mstdn.ca No? That doesn't work at all here. For it to be 6 or would have to be around 150. 50 would absolutely be more like 2 or 3. There's provincial variation in the calculations. The BC protocol most provinces switched to last year has a step where they switch over to just PM 2.5 when it's higher than the classic AQHI. Here's some info about it https://www.cbc.ca/news/canada/british-columbia/smoke-hazards-eccc-1.7209312 Anyway, it's a 3 here right now, but purple air reports numbers in the 50s.

TomWilsonYEG
@CTHW@mstdn.ca

@mariellequinton@ottawa.place
To be a 6 the pm2.5 be 50+
But looking at and comparing the pm 2.5 with the AQHI+ in Ottawa doesn't fit.
I wonder why?

Marielle Quinton
@mariellequinton@ottawa.place

@CTHW@mstdn.ca Yeah, I wish they'd tell us more specifically somewhere. Like, reading a CBC article is ok but environment Canada should have a link explaining the value exactly. It's hard to know how much to trust it.

TomWilsonYEG
@CTHW@mstdn.ca

@mariellequinton@ottawa.place

This is the explanation from PurpleAir. The URL's embedded just explain what the AQHI+ means not how it's arrived at.