David Elfstrom 🍁
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davidelfstrom.bsky.social
David Elfstrom 🍁
@davidelfstrom.bsky.social
P.Eng, Energy management, measurement & verification. Toronto, Canada. Born 327ppm CO2. Climate Action & electrification; Safer infrastructure; cycling; air filtration & ventilation
Meanwhile this is how respiratory aerosols are captured by infectious disease researchers who understand physics.
November 11, 2025 at 1:02 AM
This is literally the method they used for aerosol droplet sample collection.
November 11, 2025 at 12:55 AM
Five years ago, November 10 2020 #Toronto was a balmy 21.6 C.
Today? High of 1 C and snowing all day.
November 10, 2025 at 3:16 AM
Arg! The direct headwind component on the return trip was about 15 km/h:
cos(30°) * 18 km/h. Nice temperature though, clear sky and 13°C.
November 4, 2025 at 10:54 PM
That feeling when the wind direction is perfectly aligned with your #bikeTO commute.
November 4, 2025 at 1:34 PM
Reminds me of the old "Internet Explorer is slow" joke
October 29, 2025 at 2:50 PM
Those, and the Secret Railroad (aired on TVO)
October 24, 2025 at 7:10 PM
This dapper gentleman #caturday
October 18, 2025 at 2:05 PM
Happy 10th anniversary to the best political tweet, ever.
October 17, 2025 at 11:35 PM
The motor vehicle-centric societal thinking observed by @shawnmicallef.bsky.social is demonstrated by @ianwalker.bsky.social et al in "Motonormativity: How social norms hide a major public health hazard" doi.org/10.31234/osf... /1
September 25, 2025 at 2:55 AM
Changing the filters on the open source PC fan-based air cleaner. It was still keeping the particulate mass in the bedroom below measurable (0.1 μg/m3) but it's been running for at least 17,000 hours. /1
September 20, 2025 at 11:46 PM
Emily May Rose finished panel spray paint illustration, September 14 2025.
September 14, 2025 at 8:21 PM
Emily May Rose signs her latest piece outside Northern Contemporary gallery during the Roncesvalles Polish Festival in Toronto
September 14, 2025 at 8:08 PM
My daughter and her friends made bracelets and sold them at the street festival yesterday.

Apparently two or three people bought a pair each, and paid the higher amount!
September 14, 2025 at 1:36 PM
Find the headphone jack and insert one of these for some peace & quiet. disquiet.com/2019/06/09/d...
September 11, 2025 at 9:33 PM
New road markings have appeared in Toronto using the zig-zag pattern to indicate the passenger loading area in the curb lane adjacent to the streetcar stop. #BikeTO
September 11, 2025 at 1:21 AM
If you have a large building in Toronto (Postal Code M+), try out the new free automated energy data upload service to help with your building's reporting requirements using ENERGY STAR Portfolio Manager. 1st in Ontario!
www.torontohydro.com/energy-star-...
September 3, 2025 at 10:42 PM
Brown Bear gets his wings at the CN Tower in Toronto
#Staycation
August 21, 2025 at 11:18 PM
#Staycation Toronto report:
There's two groups taking the train downtown: #FanExpoCanada2025 and #JonasBrothers concert. Each have their own unique costumes.
August 21, 2025 at 9:59 PM
17% price hike by way of shrinkflation: $10 bag originally had 7 uncooked chicken parmesan, now contains 6. Difference in expiry dates is three months. Manufactured by the sneaky little hobbitses at Grand River Foods, Cambridge, Ontario.
August 9, 2025 at 12:07 PM
Midea makes a saddle mount cold climate packaged window heat pump that plugs into a regular outlet just like a window A/C. It's quieter, but a lot more expensive to buy than a window A/C.
August 5, 2025 at 10:03 PM
Timeline juxtaposition
August 3, 2025 at 7:23 PM
They HAD to write in the obvious "surgical masks shall not be used for respiratory protection" because of obstinate IPAC practitioners who claim otherwise.
August 1, 2025 at 12:02 AM
Unhealthy air quality from wildfire smoke over Southern Ontario today #BikeTO
July 31, 2025 at 12:47 PM
Protocol is for the driver to hug the right curb, allowing cyclists to pass safely on the left. Like in MTO's driver's handbook diagram 2-12.
July 30, 2025 at 10:07 PM