Jeff Gilchrist
@jeffgilchrist.bsky.social
PhD Biomedical researcher, data scientist, and finder of large prime numbers. Views are my own. Twitter: @jeffgilchrist Mastadon: @jeffgilchrist@mstdn.science
COVID-19 guides, stats, calculators & 600+ scientific articles: http://covid.gilchrist.ca
COVID-19 guides, stats, calculators & 600+ scientific articles: http://covid.gilchrist.ca
The graph shows a fictitious high COVID concentration example of 3 scenarios where someone without a mask could get infected from COVID within 1, 5, and 10 minutes along with various fit factors (FF). 12/
October 25, 2025 at 11:09 AM
The graph shows a fictitious high COVID concentration example of 3 scenarios where someone without a mask could get infected from COVID within 1, 5, and 10 minutes along with various fit factors (FF). 12/
How does various mask fit compare to filter the air and protect you or others?
Most masks, even baggy blue procedure masks use filtering material that can filter 95%+ of particles that pass through it, but the key is "pass through it". Continue to learn more... 🧪🧵1/
Most masks, even baggy blue procedure masks use filtering material that can filter 95%+ of particles that pass through it, but the key is "pass through it". Continue to learn more... 🧪🧵1/
October 25, 2025 at 11:09 AM
How does various mask fit compare to filter the air and protect you or others?
Most masks, even baggy blue procedure masks use filtering material that can filter 95%+ of particles that pass through it, but the key is "pass through it". Continue to learn more... 🧪🧵1/
Most masks, even baggy blue procedure masks use filtering material that can filter 95%+ of particles that pass through it, but the key is "pass through it". Continue to learn more... 🧪🧵1/
The SanKey diagram shows you variant lineages and you can follow back where that variant came from. 4/
October 19, 2025 at 12:18 PM
The SanKey diagram shows you variant lineages and you can follow back where that variant came from. 4/
Looking at specific variants, XFG.3 has dropped considerably and its descendent XFG.3.15 now takes first place at 6.2%, followed by XFG.3 at 5.2% and XFG.2 at 4.5%. 2/
October 19, 2025 at 12:18 PM
Looking at specific variants, XFG.3 has dropped considerably and its descendent XFG.3.15 now takes first place at 6.2%, followed by XFG.3 at 5.2% and XFG.2 at 4.5%. 2/
** Ontario Variant Update (to Oct. 3, 2025) **
The XFG.* "Stratus" family is accounting for 83% while the next closest variant family NB.1.8.1.* "Nimbus" is 12.8% of sequenced genomes from COVID tests. 🧵1/
The XFG.* "Stratus" family is accounting for 83% while the next closest variant family NB.1.8.1.* "Nimbus" is 12.8% of sequenced genomes from COVID tests. 🧵1/
October 19, 2025 at 12:18 PM
** Ontario Variant Update (to Oct. 3, 2025) **
The XFG.* "Stratus" family is accounting for 83% while the next closest variant family NB.1.8.1.* "Nimbus" is 12.8% of sequenced genomes from COVID tests. 🧵1/
The XFG.* "Stratus" family is accounting for 83% while the next closest variant family NB.1.8.1.* "Nimbus" is 12.8% of sequenced genomes from COVID tests. 🧵1/
I found out for Ontario that "the Ministry of Health updated the age groups on the I9 bed census data collection forms" so some data in the Ontario Respiratory Virus Tool ( www.publichealthontario.ca/en/Data-and-... ) will be grouped differently starting in September. 🧵1/
September 29, 2025 at 12:22 PM
I found out for Ontario that "the Ministry of Health updated the age groups on the I9 bed census data collection forms" so some data in the Ontario Respiratory Virus Tool ( www.publichealthontario.ca/en/Data-and-... ) will be grouped differently starting in September. 🧵1/
You can see from the Venn diagram that LP.8.1 has 4 different amino acid mutations that aren't in the XFG.5 or JN.1 spike protein, and XFG.5 has 6 amino acid mutations not present in the other two ( cov-spectrum.org/explore/Worl... ). 6/
September 9, 2025 at 12:08 PM
You can see from the Venn diagram that LP.8.1 has 4 different amino acid mutations that aren't in the XFG.5 or JN.1 spike protein, and XFG.5 has 6 amino acid mutations not present in the other two ( cov-spectrum.org/explore/Worl... ). 6/
LP.8.1 is a descendant of JN.1 from several years ago which became KP.1 before it became LP.8 as seen in the Sankey diagram. Last year's mRNA vaccines were based on KP.2 which was a different branch of variants. 4/
September 9, 2025 at 12:08 PM
LP.8.1 is a descendant of JN.1 from several years ago which became KP.1 before it became LP.8 as seen in the Sankey diagram. Last year's mRNA vaccines were based on KP.2 which was a different branch of variants. 4/
Looking at specific variants as of mid August, XFG.5.1 is most prevalent at 13%, NB.1.8.1 in second at 10%, XFG.2 in third at 8.6% and XFG.3 in fourth at 7.4%. 2/
September 9, 2025 at 12:08 PM
Looking at specific variants as of mid August, XFG.5.1 is most prevalent at 13%, NB.1.8.1 in second at 10%, XFG.2 in third at 8.6% and XFG.3 in fourth at 7.4%. 2/
*** Ontario Variant Update (to: Aug. 16, 2025) ***
Ontario COVID sequence updates have been more frequent over the past month with the XFG.* "Stratus" family of variants now at 74% of sequences, NB.1.8.1.* "Nimbus" at 22% and LP.8.1.* down to 3%. #Variants #COVID #XFG #Stratus 🧪🧵1/
Ontario COVID sequence updates have been more frequent over the past month with the XFG.* "Stratus" family of variants now at 74% of sequences, NB.1.8.1.* "Nimbus" at 22% and LP.8.1.* down to 3%. #Variants #COVID #XFG #Stratus 🧪🧵1/
September 9, 2025 at 12:08 PM
Red bars almost always > 30% and sometimes > 40% represent the % of confirmed COVID hospitalizations that are health-care associated, AKA nosocomial infection, acquired while staying in a healthcare facility. This is from 70 hospitals around Canada. See ( health-infobase.canada.ca/cnisp/viral-... ).
July 6, 2025 at 12:08 PM
Red bars almost always > 30% and sometimes > 40% represent the % of confirmed COVID hospitalizations that are health-care associated, AKA nosocomial infection, acquired while staying in a healthcare facility. This is from 70 hospitals around Canada. See ( health-infobase.canada.ca/cnisp/viral-... ).
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. 21/
June 9, 2025 at 2:23 PM
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. 21/
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.". 18/
June 9, 2025 at 2:23 PM
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.". 18/
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. 17/
June 9, 2025 at 2:23 PM
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. 17/
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. 15/
June 9, 2025 at 2:23 PM
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. 15/
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 ( aqmap.ca ). 13/
June 9, 2025 at 2:23 PM
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 ( aqmap.ca ). 13/
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.bsky.social ( visiblair.com ). 11/
June 9, 2025 at 2:23 PM
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.bsky.social ( visiblair.com ). 11/
The web version of this article with nice table of contents and easy to share with others can be found here ( tinyurl.com/AQHIwildfire ) and ( docs.google.com/document/d/1... ). 2/
June 9, 2025 at 2:23 PM
The web version of this article with nice table of contents and easy to share with others can be found here ( tinyurl.com/AQHIwildfire ) and ( docs.google.com/document/d/1... ). 2/
While disappointment remains, even Toronto Public Health is mentioning the N95 word ( x.com/TOPublicHeal... ). Still taboo outside of smoke related uses it seems.
June 6, 2025 at 9:39 PM
While disappointment remains, even Toronto Public Health is mentioning the N95 word ( x.com/TOPublicHeal... ). Still taboo outside of smoke related uses it seems.
The special air quality system from Environment Canada recommends N95 Respirators. They don't mention that the toxic gases from wildfire smoke are not stopped by the N95 though.
June 6, 2025 at 6:55 PM
The special air quality system from Environment Canada recommends N95 Respirators. They don't mention that the toxic gases from wildfire smoke are not stopped by the N95 though.
Note that PM2.5 levels are not the AQI (air quality index) but the actual measurement of particulate matter so looking at the 3rd column in the attached table (not the first column which just uses the index number). 5/
June 6, 2025 at 12:29 PM
Note that PM2.5 levels are not the AQI (air quality index) but the actual measurement of particulate matter so looking at the 3rd column in the attached table (not the first column which just uses the index number). 5/
Pollution levels in Ottawa are very high from wildfire smoke. The particulate matter (PM)2.5 levels surpassed 140 ug/m^3 Thursday evening and are still above 130 on my VisiblAir Model X outdoor sensor ( visiblair.com ). 🧵1/ #iaq #wildfire #smoke #airquality
June 6, 2025 at 12:29 PM
Pollution levels in Ottawa are very high from wildfire smoke. The particulate matter (PM)2.5 levels surpassed 140 ug/m^3 Thursday evening and are still above 130 on my VisiblAir Model X outdoor sensor ( visiblair.com ). 🧵1/ #iaq #wildfire #smoke #airquality
School Indoor Air Quality Basics.
"Easy-to-understand resources are designed for school staff and decision-makers without a technical background, helping them make informed choices about indoor air quality."
Direct link to fact sheets ( www.ashrae.org/file%20libra... ). #school #iaq #airquality
"Easy-to-understand resources are designed for school staff and decision-makers without a technical background, helping them make informed choices about indoor air quality."
Direct link to fact sheets ( www.ashrae.org/file%20libra... ). #school #iaq #airquality
June 5, 2025 at 1:20 PM
School Indoor Air Quality Basics.
"Easy-to-understand resources are designed for school staff and decision-makers without a technical background, helping them make informed choices about indoor air quality."
Direct link to fact sheets ( www.ashrae.org/file%20libra... ). #school #iaq #airquality
"Easy-to-understand resources are designed for school staff and decision-makers without a technical background, helping them make informed choices about indoor air quality."
Direct link to fact sheets ( www.ashrae.org/file%20libra... ). #school #iaq #airquality
Now only a small # of sequences coming from NB & Quebec and periodically a few from AB, BC, and NS for all of Canada. You can see the big drop in Canada sequences when ON stopped submitting so very difficult to track what is going on. 2/
March 15, 2025 at 2:56 PM
Now only a small # of sequences coming from NB & Quebec and periodically a few from AB, BC, and NS for all of Canada. You can see the big drop in Canada sequences when ON stopped submitting so very difficult to track what is going on. 2/