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
Reposted by David Elfstrom 🍁
fraggle rock implies the existence of fraggle jazz and fraggle rap
February 3, 2026 at 5:55 PM
On-street parking on Bloor St. has been clear of snow for six days while snow makes the bike lane unusable. Excess snow should be dumped in the on-street parking spots. Prioritize movement of people, not storage of private property on a public road.
Yes, we had a major snow event.

Yes, the city is triaging, and many sidewalks in particular still need work.

But it's been a week and arterial bikeways are remain unrideable and worse appear to be dumping grounds for snow-clearing.

What's the plan, Toronto?

www.torontotoday.ca/local/transp...
Toronto cyclists frustrated by snow-blocked bike lanes week after record storm
Biking advocate Michael Longfield of Cycle Toronto is calling on the city to communicate a clear plan for removing snow from bike lanes
www.torontotoday.ca
February 1, 2026 at 10:41 PM
I allow myself to only watch movies/shows if I simultaneously do a Zone 2 indoor bike ride.

Today was different: I saw that @techconnectify.bsky.social had a new video out, checked out the duration, and knew I was in for a 1h 32 min treat. Tears welling up at the end.
You are being misled about renewable energy technology.
YouTube video by Technology Connections
www.youtube.com
January 31, 2026 at 8:25 PM
Reposted by David Elfstrom 🍁
"If we already have good reason to believe a treatment works, randomizing people to a placebo means knowingly denying them benefit. That’s not science. That’s harm in the name of methodological purity."

This. 1000x.🔥

Going to forward to a local gang RCTing portable HEPA units. In hospital rooms.
January 30, 2026 at 3:41 AM
Reposted by David Elfstrom 🍁
This is really sad... we actually need to test and fix the environments we are living, working, and playing in...

cbc.ca/news/health/radon-gas-cancer-screenings-9.7058488
A toxic gas was hiding inside his home for decades. It's radon, and scientists are tackling its deadly rise | CBC News
Radon gas, an invisible health threat that can build up in your home, is putting more Canadians at risk of deadly lung cancer. A national research team is using throwaway toenail clippings to find mar...
cbc.ca
January 27, 2026 at 2:53 AM
I took some thermal images of the building featured in this post by @lloydalter.bsky.social: lloydalter.substack.com/p/in-praise-...
ALT: Heat loss at street level podium glazing, and in the tower where each floor slab intersects the exterior wall. After sunset -10 C ambient.
January 27, 2026 at 1:30 AM
I only watch movies while doing a Zone 2 indoor bike ride.

Sunday's 2 hour ride was Sorcerer (1977).
🧵/1
January 26, 2026 at 5:44 AM
Whoops! Forgot to lower the humidifier's set point to account for the lower outdoor temperature! Ice and water formed on our condo's window wall. This is at ambient humidity of 37% at 19 C. The window is much colder.
January 25, 2026 at 1:03 AM
Here. Have a thermal video of my cat leaving behind a warm butt print and paw prints.

May it distract you from both the cold and the ICE. #caturday
January 24, 2026 at 11:41 PM
As the temperature in Toronto goes from above freezing on Thursday to -25 C by Friday night, you may be woken by one or more loud CRYOSEISMS, or frost quakes. I remember them from the winters of 2014 and 2015. A loud BANG in the middle of the night.
January 23, 2026 at 3:03 AM
New from @donmilton.bsky.social Public Health Aerobiology Laboratory (PHAB Lab) at the University of Maryland School of Public Health: GUV Hub for all things about germicidal ultraviolet for clean air.
⭐We are excited to present the GUV Hub website!⭐

The GUV Hub is a reliable source for learning about Germicidal Ultraviolet (GUV) technology.

Visit us at guv.umd.edu

#PublicHealth #InfectionControl #IndoorAirQuality #GermicidalUltraviolet #GUV #PHABLab #Science
January 21, 2026 at 10:14 PM
Today I learned that some devices with a USB-C port will only charge with a USB-A to C cable. USB-C to C doesn't work. Had me thinking my device was dead!
January 21, 2026 at 2:32 AM
Reposted by David Elfstrom 🍁
"If your home has a fuel-burning appliance, a fireplace or an attached garage, you must install a working CO alarm adjacent to each sleeping area and, as of January 1 2026, on every storey of the home" One nice thing about going carbon-free is not having to do extra safety work. #onpoli #TOpoli
Carbon Monoxide Alarms
Updates to the Ontario Fire Code took effect on January 1, 2026. Select the housing type below to understand how these changes impact you.   Single-Family Dwellings Care Occupancies Multi-Unit Dwellin...
www.toronto.ca
January 19, 2026 at 8:51 PM
Another excellent video, this time about a brand new transit line that has fundamentally bad design priorities
How can a NEW Transit Line be THIS BAD!? (Finch West LRT)
YouTube video by Not Just Bikes
youtu.be
January 18, 2026 at 2:11 PM
Most nights when walking the dog I hear a whale call sound from a passenger jet. I used to think it was landing gear extension but it's too loud for that and not on the final approach. Turns out it's a particular engine! Thanks @northernnerd.bsky.social ! #Roncesvalles #Toronto
It's a specific engine.

I'm assuming whenever they're on this approach path it just happens to be at an appropriate power setting that midtown gets serenaded with whale song.
January 18, 2026 at 2:59 AM
Park around and fined out
#toronto #ttc #Roncesvalles
January 16, 2026 at 1:23 AM
Quietly snuck into my daughter's room and turned off her alarm for the rare event of a snow day for Toronto schools
All TDSB schools and sites, including child care centres, are closed today due to the weather forecast.
With a snowfall warning in effect, we will continue to monitor weather conditions and share any updates on buses or schools by 6 a.m. tomorrow.
January 15, 2026 at 11:27 AM
Reposted by David Elfstrom 🍁
Using numerical modeling, researchers determine portable air cleaners remove most particles below ~5 microns, deposition removes most above 10 microns. Ventilation plays minimal role at 0.5/h air changes, but starts to equate to air cleaner at 2 /h.

onlinelibrary.wiley.com/doi/pdf/10.1...
January 8, 2026 at 1:01 PM
Reposted by David Elfstrom 🍁
Additive electronic portable air cleaners (ionizers, photo catalytical oxidizers, plasma), perform worse than typical HEPA filters for pathogen reduction.

pubs.acs.org/doi/full/10....
Contextualizing Equivalent Clean Airflow Rates for Airborne Pathogens of Ionizers and Other Electronic Indoor Air Cleaners
Additive electronic air cleaners like ionizers, photocatalytic oxidizers, and plasma devices intentionally release reactive species into indoor air so that they may inactivate infectious airborne pathogens. Third-party commercial testing and peer-reviewed studies alike typically report inactivation metrics in terms of percent- or log-reductions observed from chamber experiments that imply a nearly complete elimination of infection risks. However, these metrics are highly dependent upon the experimental volume and duration, so they do not directly translate to actual effectiveness indoors. We reviewed 45 experiments across 14 published studies and converted reported reduction metrics into equivalent clean airflow rates (ECA). Different studies yielded distinct ECA distributions, suggesting that differences in experimental procedures, device specifications, or environmental conditions may be more important ECA determinants than the target pathogen or the underlying device technology. Study-averaged ECAs spanned between 1.4 and 134 m3/h, with the median study having an average ECA = 31 m3/h. Even small off-the-shelf HEPA-filter air cleaners typically provide ECAs that exceed the best-performing additive devices analyzed herein. Their low efficacy relative to alternatives, environmental factors that can affect performance, and chemical byproduct concerns are discussed in the context of test standard development and system selection.
pubs.acs.org
January 5, 2026 at 1:26 PM
Reposted by David Elfstrom 🍁
A good Caturday post this week, including items on the building of cat stairs to rescue cats falling into Amsterdam's canals, and an observation (and hypothesis) of why most cats sleep on their left sides.

bit.ly/4aI0pCd
January 3, 2026 at 4:05 PM
Happy New Year, pocket pals!
Happy New Year phone friends!
January 1, 2026 at 4:27 PM
Reposted by David Elfstrom 🍁
Hey Canadians, if you followed storm chaser Mark Robinson from the Weather Network on the bad place, he's here too. He doesn't post much, but maybe we can get him to if we flood him with follows! @stormhunter.bsky.social
December 29, 2025 at 6:19 PM
Reposted by David Elfstrom 🍁
Whenever I see a surgical mask in use, I engage in conversation. Even if its a doctor at a hospital.
Many honestly are not educated in airborne pathogen prevention....yet.
A hindrance to switching from surgical to N95/respirator is cost unfortunately😔
Thanks to @donatemask.bsky.social there is a way
December 29, 2025 at 6:10 PM
Anyway we had a relaxing off-grid family getaway this long weekend. Introduced kid #2 to the board games of checkers and Pictionary and got some great sledding in.
While smartphones do a great job of basic image processing that used to take a lot of time with digital photography, they are increasingly altering reality for an algorithmic preference. Example shown: Extracting too much detail from shadows and over-correcting white balance.
December 29, 2025 at 2:15 AM