Jeff GilchristUnderstanding Canadian Air Quality Health Index (AQHI) & Wildfire Smoke
Wildfire smoke consists of toxic gases and particulate matter (PM) when breathed in gets into our lungs, bloodstream, and even our brain. 🧵1/
The web version of this article with nice table of contents and easy to share with others can be found here ( https://tinyurl.com/AQHIwildfire ) and ( https://docs.google.com/document/d/1s99C1lTgKyNoYKAnP3fE4E1vx8T-6Vd2a-Ea1JMRlH4/edit?usp=sharing ). 2/
When smoke stays in the air for prolonged periods of time, the UV radiation from the sun interacts with all the volatile organic compounds (VOCs) to form even more toxic gases ( https://theweathernetwork.com/en/news/weather/severe/smelling-plastic-millions-are-in-the-path-of-toxic-smoke-plumes ). 3/
This is the case for the gases from wildfire smoking travelling from thousands of kilometers away and arriving in far away cities like we are seeing now.
Benzene and formaldehyde are being created in the atmosphere from the smoke + UV radiation which can sometimes smell like plastic and can have very adverse effects on human/animal health. 4/
Well fitting respirators like N95 masks will do a great job at filtering out the PM2.5 particles from the air if you are outside, but they are not designed to filter out all the smoke related gases. 5/
The AQHI is a Canadian scale that is supposed to show the health risk associated with the air pollution we breathe and combines multiple pollutants, including nitrogen dioxide (NO2), particulate matter (PM2.5) and ground-level ozone. Unfortunately it doesn't seem to provide an adequate mapping for the long-term cumulative dangers from wildfire smoke. 6/
For example, an AQH index of 1-3 is considered "Low" where at risk populations can "Enjoy your usual outdoor activities." and for the general population "Ideal air quality for outdoor activities." ( https://www.canada.ca/en/environment-climate-change/services/air-quality-health-index/understanding-messages.html ).
That wording implies that the air quality is great and nothing to worry about. An index of 3 is mapped when Particulate Matter (PM) from wildfire smoke is between 20 ug/m^3 and 30 ug/m^3. 7/
The PM2.5 levels from smoke have dropped significantly from previous days to 25.96 ug/m^3 which the AQHI maps to an index of 3. These PM readings were done on a Canadian made Model X air quality monitor from @VisiblAIr ( https://visiblair.com/ ). 8/
What most people likely don't realize is that breathing in 22 ug/m^3 of PM2.5 for a day is the equivalent of smoking 1 cigarette but possibly worse taking into account the additional toxic gases that have formed as the smoke has travelled ( https://berkeleyearth.org/air-pollution-and-cigarette-equivalence/ ). 9/
Even if you can't see or smell the smoke outside, check your local particulate matter levels (PM2.5) using a tool like this one that combines multiple sensors in many cities to see what the levels are currently ( https://aqmap.ca/ ). 10/
If you plan to spend 8 hours outdoors but would not be willing to smoke half a cigarette then you might want to wait until PM levels are below 20 ug/m3 or an AQHI of 1-2, otherwise you will be exposed to an equivalent amount of pollution. 11/
Smoking 1 cigarette is the equivalent of 8 hours of exposure at the top of AQHI level 6 (PM2.5 60 ug/m^3) where they recommend "No need to modify your usual outdoor activities unless you experience symptoms such as coughing and throat irritation." for the general public. 12/
The AQHI also stops at an index of 10 when PM2.5 levels reach 90-100 ug/m^3 and then switch from 10 to "+" above 100 ug/m^3 so you don't get a sense of just how bad the air quality is when levels are higher than 100 ug/m^3. 13/
In the summer of 2023, PM2.5 levels reached 511 ug/m^3 in Ottawa but that is also displayed as "+" despite it being equivalent to smoking 7.7 cigarettes after 8 hours of exposure compared to 1.5 cigarettes after 8 hours when the AQHI first bumps up to the "+" level. 14/
The AQHI even at the highest index of 10 still only recommends to the general population "Consider reducing or rescheduling strenuous activities outdoors if you experience symptoms such as coughing and throat irritation.".
The Very High level of "+" above 10 is, "Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation." 15/
When the PM2.5 levels outside are more than 500 ug/m^3 like in 2023, you don't want to reduce strenuous activities outdoors, you want to avoid them completely. 16/
The US EPA Air Quality Index (AQI) has category breakpoints up to PM2.5 225.5 ug/m^3 which provide "Very Unhealthy" and "Hazardous" categories above what the Canadian AQHI display. These at least warn that risk of effects is increased for everyone and the Hazardous level is a Health warning of emergency conditions. The AQI numbers continue to increase as well so you can tell just how much higher the pollution levels are. 17/
While there is no safe level of PM2.5, the WHO recommends limiting levels to below 15 ug/m^3 in a 24 hour period to reduce the burden of disease from stroke, heart disease, lung cancer, and both chronic and acute respiratory diseases, including asthma ( https://who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health ). The WHO wants cities to target less than 5 ug/m^3 pollution. 18/
Exposure to wildfire smoke can cause damage to the lungs, blood, and heart ( https://woods.stanford.edu/news/health-impacts-wildfire-smoke ).
PM2.5 means particulate matter that is 2.5 microns in size or less and they are small enough to work their way deep into the lungs and bloodstream where they can trigger heart attack, stroke, lung cancer, and asthma. 19/
More recent studies have shown that PM2.5 is also strongly associated with brain damage such as cerebrovascular damage (stroke) and neurological damage to the brain which can impact cognitive function, dementia, and psychiatric disorders ( https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2022.967174/full ). 20/
"PM2.5 can pass through the lung–gas–blood barrier and the “gut–microbial–brain” axis to cause systemic oxidative stress and inflammation, or directly enter brain tissue via the olfactory nerve, eventually damaging the cerebral blood vessels and brain nerves."
Even smaller particles also exist in wildfire smoke that could enter the brain within the nerve fibers to the olfactory bulb which connects your nose to your brain for smelling ( https://environmentalhealth.ucdavis.edu/air-pollution/brain-health ). 21/
Air Pollution and Brain Health
By Pamela J. Lein, PhD and Anthony S. Wexler, PhDHuman exposure to unhealthy levels of air pollution is now a worldwide public health problem, and in heavily urbanized areas of both developing and developed countries, levels of some air pollutants can exceed safe air quality standards by a factor of 10 or more.
Children exposed to 5 days of wildfire smoke have a 2x increased rate of asthma and people over 65 face a 40% increase in rate of strokes and an increased rate of heart attacks.
Anyone who is pregnant is also at higher risk of premature birth and decreased birth weight after wildfire smoke exposure. 22/
Any exposure to particulate matter pollution will cause inflammation in the lungs and has a cumulative effect that may compromise immune surveillance of the lung from impaired immune cell function and lymphoid architecture making people more susceptible to infectious disease and cancers of the lung ( https://www.nature.com/articles/s41591-022-02073-x ). 23/
Inhaled particulate accumulation with age impairs immune function and architecture in human lung lymph nodes - Nature Medicine
Carbon-containing particulates accumulate with age in a subset of macrophages in human lung-associated lymph nodes, decrease macrophage phagocytic capacity and turnover and disrupt lymphoid tissue structure, potentially compromising adaptive immune responses.
Studies have even shown long-term impacts to exposure from wildfire smoke, where months after smoke events happen, there are more severe influenza infections the following flu season ( https://www.sciencedirect.com/science/article/pii/S0160412019326935 ). 24/
They hypothesize this is because people's immune systems still haven't fully recovered from the damage caused by the smoke.
This isn't limited to just the flu, if your immune system in the lungs is damaged or supressed from wildfire smoke, then even months later you could be more likely to get infections and they could be more severe. 25/
Guidance for Cleaner Air Spaces during Wildfire Smoke Events ( https://www.canada.ca/en/health-canada/services/publications/healthy-living/guidance-cleaner-air-spaces-during-wildfire-smoke-events.html ). 26/
You can use HEPA filters indoors to improve air quality or build your own DIY filters using furnace filters with some tutorials in multiple languages from Shiven Taneja available here ( https://drive.google.com/drive/u/1/folders/1MohBj1ctcNBrXQCWBByRgojXyb3bh7mi ). 27/
To learn more about the Importance of Indoor Air Quality: Wildfire Smoke & Cooking please read ( https://mstdn.science/@jeffgilchrist/112475293271117216 ). 28/
Jeff Gilchrist (@[email protected])
Attached: 3 images Indoor Air Quality: Wildfire Smoke & Cooking With wildfire smoke season here, we all need to think about air quality inside where we spend most of our time. This article provides multiple examples measuring the air quality inside my home from wildfire smoke and cooking. The web version of this article with nice table of contents and easy to share with others can be found here ( https://docs.google.com/document/d/1x0yA0ebo8HkNYCps_CZPqGE0-My_4toLiGSR9M-D7-w/edit?usp=sharing ). #IAQ #IndoorAirQuality #Ventilation #CO2 #PM #Pollution #Smoke #wildfire
Nicole ParsonsConsidering the high cost of fossil fuel climate change from wildfires alone, it's still surprising that Canada sends $30 billion in fossil fuel subsidies to the wealthiest & most corrupt industry on the planet.
https://www.bbc.com/weather/articles/c4g2k9lzjeko
Taxpayers forced to subsidize an industry making them sick & forced to subsidize pipelines for a toxic product overdue for a phase out.
https://en.m.wikipedia.org/wiki/2024_Jasper_wildfire
Krupo@jeffgilchrist thanks for this entire thread. I felt like getting a fancy air purifier was maybe overkill but this affirms that it was probably a good call.
The associated all provides the local UAQI reading (63 in Toronto right now). I assume that's the updated AQI in this graphic's column, eh?