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Discussion: PM 2.5 measurement, I assume?

in: Carbons Offset; Carbons Offset > 2023-07-18

Jul 19, 2023 2:49 PM # 
An Australian Attackpointer recently posted their national best practices for wildfire smoke and exercise. It's very specific and should be useful. I haven't seen anything comparable for Canada.
Jul 21, 2023 4:36 AM # 
Carbons Offset:
Yes, that’s PM2.5. The Purple Air Map shows multiple monitors in the area which can be used to give some confirmation of each other in real time.
Thanks for the link. The link didn’t work for me but your description of the post enabled me to google it. Here is the report I found:
Maybe my gut feel was pretty good. If I had to boil the report down to one criterion, I would tell people that 150 micrograms per cubic metre is a guideline threshold they can use to decide when exercise is causing more harm than benefit (lower levels if you have additional concerns or challenges like asthma etc.).
Jul 21, 2023 4:39 AM # 
Carbons Offset:
Here is the link to the map of Purple Air monitor readings. I would consider getting my own monitor (about $300, I believe) but someone who lives right by me has one.
Jul 21, 2023 10:20 AM # 
Wow, good find. There is one in Orangeville near us but none up near Kolapore or Collingwood.
Jul 21, 2023 12:33 PM # 
Thanks - looks like they reorganized their website as soon as I shared the link! (Eyeroll emoji.) I read it differently. When PM2.5 is Poor (51-150), they suggest that outdoor high intensity endurance activities (as one example) can be an issue even for healthy people. It makes sense that different types of exercise would be viewed differently, given that PM2.5 exposure is like a range of the number of cigarettes smoked. There isn’t really a “healthy” level - just a “less bad” level. Also, at the moment, they’re basing recommendations on short term symptoms even though they know PM2.5 is linked to higher levels of heart and lung disease in the long term.

I’ve been thinking of getting a monitor. I’ve been checking IQ Air but Purple Air looks like a great addition!
Aug 1, 2023 11:57 PM # 
Carbons Offset:
I just realized that the monitored values I was looking at aren’t true PM2.5 concentrations in ug/m3 (micrograms per cubic metre), they are expressed as “US EPA PM2.5 AQI”. So, they are an air quality index based on the PM2.5. These may be the same values as used on the IQ Air app and website; the values seems similar. This is the default display value on the Purple Air Map. There is a drop down menu where you can select different displays. If I select Tasmanian PM2.5 scale (ug/m3), it appears to be pure values of PM2.5, not an index. Right now our reading is 57 ug/m3 on the Tasmanian PM2.5 scale, and 152 on the US EPA PM2.5 AQI. On the Canadian AQHI display option on this map, our reading is 3 on a scale of 1 to 11. So, the Canadian Index claims it is ideal air quality for outdoor activities (1-3 range). I can assure you it is not ideal outside right now. Meanwhile the US EPA AQI says some people may experience health effect and sensitive people may experience more.

Based on the Australian AQI: 233. >200: Hazardous: Sensitive groups should avoid all outdoor activities. Other adults should avoid strenuous outdoor activities.

Based on the European AQI: 58. 50-75: Very Poor. Consider reducing intense activities outdoors, if you experience symptoms such as sore eyes, a cough or sore throat. Sensitive groups should reduce physical activities, particularly outdoors.

So it seems like the Australian interpretation is the most cautious and the Canadian one is a joke.
Aug 2, 2023 1:45 AM # 
I was volunteering on a Town Air Quality committee when AQHI was introduced to "simplify things" because they felt citizens couldn't understand real data. Ugh!!! PM2.5 in ug/m3 is the number that matters this summer. AQHI just obscures what is happening. Also, AQHI is based on short-term, immediate health issues and ignores any long term effects.

A friend sent me this Toronto Star article about a big problem with AQHI and PM2.5 in different Canadian provinces. Apparently BC did the best job of adapting to wildfire smoke so the feds adopted their system. Alberta created its own system (go figure!) which is better than Ontario's but probably not as good as BC's. And Ontario is stuck in the dark ages.

Wildfire smoke: Why you may not be getting the best air-quality information

With wildfires affecting large swaths of Canada, the Air Quality Health Index is being watched closely. But it can obscure the true health risks.

Kate Allen
By Kate AllenClimate Change Reporter
Thu., June 29, 2023

The federal government recently updated its air quality index to better reflect the threat posed by wildfire smoke — but Ontario isn’t using the improved system, leaving gaps between the information available to the public and the true health risks.

By 1 p.m. Wednesday, concentrations in east Toronto of fine particulate matter — a dangerous form of air pollution linked to a litany of both short- and long-term health problems — measured at almost 100. That’s according to raw data from a provincial monitoring station, which is posted online hourly. Levels that high present health risks for everyone, regardless of age or pre-existing conditions.

But the Air Quality Health Index (AQHI) in east Toronto at the time sat at 5, or “moderate” — a category that indicates that the general population does not need to worry about usual outdoor activities, while high-risk groups, like children and people with respiratory conditions, should only “consider” rescheduling.

As large swaths of Canada continue to struggle with severe air pollution caused by an unprecedented wildfire season, the AQHI is suddenly being watched closely by people making health decisions for themselves and others, said Céline Audette, of Environment and Climate Change Canada.
“The daycares, the seniors homes, all those facilities that take care of our people at risk,” said Audette, a policy analyst in health and air quality forecast services. “They are paying attention.”
Environment Canada’s new, enhanced index was adopted from British Columbia — a province that has racked up a lot of experience with smoke. During one particularly bad wildfire summer in B.C., scientists and the public alike both recognized that the AQHI was not matching the true conditions on the ground.

“We have to understand that the AQHI was not originally designed to reflect the risks associated with wildfires. It was designed to reflect the risks associated with urban air pollution,” said Sarah Henderson, scientific director of Environmental Health Services at the British Columbia Centre for Disease Control.
Historically, the AQHI was calculated using concentrations of three types of unhealthy air pollutants: nitrogen dioxide, ground-level ozone, and fine particulate matter, or PM2.5. During a typical urban smog day, these three pollutants tend to build up slowly and linger like a dome. The two pollutants the index weights most heavily in its final risk score are nitrogen dioxide and ozone, and it uses a three-hour average to reflect this slower-building threat.
“Wildfire smoke is a totally different ballgame,” Henderson explains.

Plumes of wildfire smoke arrive and dissipate unpredictably, creating sudden, rapid spikes in pollution. Neither nitrogen dioxide nor ozone is particularly relevant during wildfires. The big risk comes from PM2.5, the third pollutant the AQHI relies on, which can suddenly skyrocket as the other two stay flat — just as Toronto saw on Wednesday afternoon.

Part of what motivated B.C. to update the air quality index was that the public noticed this mismatch, Henderson said.

“People were telling us, ‘Hey, it’s smoky in my community, and the AQHI is a 2. What’s going on?’” People were losing confidence in the best tool that we have to communicate about air quality as health risks. We didn’t want that to happen.”

For scientists such as Henderson, the other major motivation was that their own research showed most of the risk during these smoky wildfire days occurred quickly, within the first hour of PM2.5 levels spiking. The province needed a system that responded faster.

B.C.’s AQHI now calculates two scores at the same time: the three-hour average of the three major pollutants, the mix usually found during an urban smog day; and the one-hour average of fine particulate matter alone, which better reflects wildfire smoke. Whichever results in the higher AQHI score is the one the public sees.

In 2020, Environment and Climate Change Canada began rolling this enhanced AQHI out across the country, Audette said.

“Some of the smaller provinces that have less policies to go through to to implement the new formula, they were able to implement it right away. We’re still working with some of the other partners, and they’re working with their senior management to implement it in their jurisdictions.”

A spokesperson for Ontario’s Ministry of Environment did not answer questions about why the province hasn’t adopted the enhanced AQHI or when it plans to do so.

“Ontario is currently working in collaboration with Environment and Climate Change Canada and evaluating options for enhancing the AQHI program to include a PM2.5 trigger, in addition to the current process of using the cumulative effects of ozone, nitrogen dioxide and fine particulate matter,” Gary Wheeler wrote.

Alberta already uses an enhanced air quality index that overrides the mixed-pollutant result when single value spikes up, but uses a different formula; the province is considering switching to the federal system, a spokesperson said. Quebec uses a different system that reports PM2.5 directly.

Audette urged Canadians to continue to pay attention to the AQHI, but also to look out for Special Air Quality statements, which are issued by Environment Canada directly: “once there’s a special air quality statement, that is your confirmation that there’s an actual problem.

“It’s staggering right now,” she added. “We’ve never been in this situation.”
Aug 2, 2023 1:49 AM # 
I like that IQ Air gives you AQI *and* PM2.5 in ug/m3 so you can make your own decisions.

I hadn't noticed that Purple Air was different units because it seemed close to the PM2.5 values I'd been seeing!
Aug 2, 2023 1:52 AM # 
In Ontario, we also have this information if you click past the simplistic AQHI page. But for us, the nearest provincial air quality monitors are a 40+ minute drive east or south. So those personal Purple Air monitors are looking good.
Aug 2, 2023 4:47 PM # 
Carbons Offset:
Thanks for sharing this! This article explains a lot of what I was starting to wonder, when the ratings just didn’t match what I was seeing and smelling.
Yes, the NOx and ozone values are probably of little value in Canmore whereas they may be relevant in Calgary.

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