Wildfire smoke - now extra toxic plumes from sun UV
Did you know just one of the many fires burning in Quebec is the size of an entire Canadian province (PEI), or large enough to stretch between the cities of Ottawa and Montreal or Toronto to Niagara Falls? 🧵1/
Read on to learn more about why the smoke now smells like plastic and the health impact. An unrolled one-page web view for this long thread that may be easier to read or share can be found here ( ). 2/
You can see from this fire smoke map that tiny PM2.5 aerosols don't just drop 6 feet away but can travel all over the continent with the smoke from northern Quebec blanketing New York City and even producing hazy skies in Europe ( ). 3/ https://t.co/lBbNeaHVYPfiresmoke.ca/forecasts/curr…
Instead of the classic smell of burning wood in a fireplace or campfire, things are starting to smell more like burned plastic so what is going on? 4/
It turns out that 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. 5/
Now benzene and formaldehyde are being created in the atmosphere from the smoke + UV radiation which happen to smell like plastic but are toxic and can have very adverse effects on human/animal health ( ). H/T: @lisa_iannattone 6/ https://t.co/wYhh4UZJ48theweathernetwork.com/en/news/weathe…
Besides the PM2.5 particles in the smoke that can get into your lungs and bloodstream, wildfires smoke it also full of various toxic gases in the form VOCs and by-products like formaldehyde and benzene as we saw above. 8/
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. 9/
You can learn more about how filtration material in N95s and HEPA filters actually filter out the tiny PM2.5 particles despite them being smaller than the holes in the material ( ). 10/
While it is much better to wear a good mask outdoors during wildfire smoke events that filter the PM2.5 particles than nothing, you are still getting exposed to other toxic gases. 11/
There are elastomeric respirators with special cartridges that will filter out both the PM2.5 particles and also various gases which would provide better protection outside from smoke ( ). 12/cdc.gov/niosh/npptl/re…
If N95s can effectively filter out tiny smoke PM2.5 particles, why can you still smell things while wearing a good mask? While PM2.5 particles are 20x smaller than the width of a human hair, the gases you smell can be billions of times less atomic mass than PM2.5 particles. 13/
A dalton (Da) or unified atomic mass unit (u) is commonly used in physics and chemistry to express the mass of atomic-scale objects such as atoms, molecules, and elementary particles ( ). 14/en.wikipedia.org/wiki/Dalton_(u…
The mass of formaldehyde is 30 Da while benzene is 78 Da. Compare this size to a single virus particle (virion) at 6 billion Da or an aerosol droplet at 160 billion Da, both monstrous sizes in comparison ( ). 15/
That is why molecules like oxygen (16 Da) can get in through respirators to you and exhaled carbon dioxide (44 Da) can get out so you don't suffocate. 16/
But it also means that toxic gases from wildfire smoke can get through N95 masks and why you can smell them so you may still want to limit your time outdoors during smoke events even while wearing a mask. 16/
Another thing I discovered is that Canada's Air Quality Health Index (AQHI) is not the best measure to use for wildfire smoke events. 17/
Ontario's AQHI readings actually weighs other pollutants much more than PM2.5 and was designed for urban car/factory pollution which builds slowly so they only look at 3 hour averages while wildfire smoke can jump quickly ( ). 18/thestar.com/news/canada/20…
Right now the Ontario AQHI level is rated at 4, the first level of moderate risk on a scale that only goes up to 10 ( ). 19/ https://t.co/3z3ucLmIazairqualityontario.com/aqhi/today.php…
USA has a PM2.5 air quality index (AQI) that goes up to 500. While the AQHI is showing 4 (yellow), the first level above low risk, the USA index is showing 158 (red) which they rate as unhealthy and the levels of concern increase much more rapidly ( ). 20/ https://t.co/gbu48iFOtPairnow.gov/aqi/aqi-basics/
For smoke, it is better to look at the actual raw PM2.5 levels to see what is going on so you don't have to worry about conversions. This time last year PM2.5 levels in Ottawa would typically range between 2-6 ug/m^3. 21/
Right now in Ottawa raw PM2.5 levels are 70 ug/m^3 which many air quality sites will provide PM2.5 such as PurpleAir here ( ) and even the Ontario air quality stations which is better than following their AQHI version ( https://t.co/0LGQ014KZE ). 22/ https://t.co/NvoFe3Bkyqmap.purpleair.com/1/m/i/mPM25/a1… airqualityontario.com/history/pollut…
Since healthcare professionals are warning that there are no known safe levels of PM2.5 it would be prudent to limit exposure as much as possible. You can read more about the equivalent amount of cigarettes at various levels of PM2.5 here ( ). 23/
Wildfire PM2.5 Air Pollution and Equivalent Cigarettes
Ottawa, Ontario and surrounding area has again been engulfed in high levels of PM2.5 pollution from wildfire smoke equivalent to smoking 1 cigarette every 2 hours. This thread will also include health protection tips.🧵1/
There are several PurpleAir air quality monitors in Ottawa with this station showing the rapid increase in US EPA PM2.5 air quality index (AQI), higher being worse ( ). 3/ https://t.co/2k9F846wVMmap.purpleair.com/1/m/i/mAQI/a10…
While the AQI is an index, the actual PM2.5 pollutant is measured in micrograms per meter cubed (ug/m^3) and there is a handy calculator and table found here to convert between the two ( ). 4/aqicn.org/calculator
Lots of places in Canada and USA now impacted with bad air pollution from forest fires. Reminder that running bathroom exhaust fans for long periods of time could likely pull more outdoor air into your home as seen on this graph inside my home. 🧵1/
Particular matter (PM) levels skyrocketed in the city today from forest fire smoke but thankfully our HVAC filter and HEPA filters inside the house are keeping levels 100x lower than outside. 2/
The reason running exhaust fans bring in more outside air is because the air going out of your house from the fans needs to be replaced with makeup air which often gets pulled int from cracks/holes in the house. When outdoor is polluted/bad you want to avoid doing that. 3/
After a bit of a dip down, XBB.1.16 "Arcturus" is really taking off now accounting for 20% of sequences while XBB.1.9.1 "Hyperion" remains level around 5%. XBB.1.5 "Kraken" no longer has the majority at 38% and dropping. 🧵1/
Fit Testing to ensure a good seal on your mask [Part 2]
This thread describes my quantitative fit testing experience with some real-world results of various types of #masks including #NIOSH#N95 and ear loop and how 1 mask leaked 70x more than the other on my face. 🧵1/
The table of contents with quick links and unrolled one-page web views for this multi-part thread can be found here (
Fit Testing to ensure a good seal on your mask [Part 1]
This thread explains what mask fit testing is (qualitative and quantitative), why it is important, and my testing experience with some real-world results of various types of masks including NIOSH N95 and ear loop. 🧵1/
The table of contents with quick links and an unrolled one-page web view for this long thread that may be easier to read or share can be found here (
Part 1 explains the difference between qualitative and quantitative fit testing, while Part 2 will show results from my own fit testing (one mask leaked 42x more than another) and details on more than 350 fit tests from others. 3/
It is important to actually test and verify your ventilation systems to ensure they are working properly. The good news is my HVAC filter works *very* well. Apparently the outside air is worse than frying eggs constantly in my house. 🧵1/
I was used to seeing very little Particulate Matter (PM) in my house throughout the winter except when we cooked/fried on our electric stove which can make a *lot* of PM. If you fry bacon, you can get PM levels from 30-50 ug/m3 so a lot more than the eggs in this graph. 2/
If you have a ventilation fan above your stove, it is important to have that running when you are cooking to help get the PM generated out of the house instead of in your lungs ( canada.ca/en/health-cana… ). 3/