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Carbon monoxide poisoning from 3D laser printer may have killed Berkeley couple (cbslocal.com)
425 points by mbgaxyz on Jan 28, 2017 | hide | past | web | favorite | 210 comments

Hi folks. Val and Roger were dear friends, and I am on the ground here, and I'd like to respectfully ask that you refrain from speculation. The press is rushing to print sensational items, and they don't know the actual facts.

I've been talking to the police directly, and nothing is conclusive yet. Nothing has actually been ruled out, nor determined to be the cause. They don't even have full toxicology reports yet, those take days and sometimes weeks.

On a personal note, I can tell you that there were two devices in the house, a small 3D printer, and a small laser cutter, that were used for building models and rigs for scientific research. Val was an immaculate engineer, and conformed to all safety rules in operating these machines. To the best of our knowledge, neither of the machines were operating the night they passed away.

Again, please refrain from fear-mongering and speculation. I know it's natural for engineers to attack unsolved problems, but you are not working with correct or full data. Once more data is available, we will write up a complete and truthful statement to try and provide closure on this issue.

Thank you all for your condolences. If you would like to honor Val and Roger's memory in the future, please stay tuned to announcements on http://fb.me/valandroger. We are hoping to establish an MIT scholarship in their names, and continue work on Roger's unfinished video game.

To answer some of the questions in this thread all at once:

1. The unit was about 900 square feet. Looks like someone calculated roughly that from the publicly available information.

2. The laser cutter itself was a very small device. I don't remember the exact size, but the cutting bed wasn't more than 2 by 2 feet, and likely smaller than that.

3. Most importantly, from what the investigators told us, the laser cutter bed was completely empty and it wasn't running when they found it. The same goes for the 3D printer.

Friends here on the ground have their ideas based on what we know about the apartment, and we have made suggestions to the investigators. We are hoping they do due diligence. While I'd like to tell you more, we are trying to avoid all speculation. We know it's stressful, but please hang in there.

Sorry to hear that you lost two friends. It's such a terrible thing for the hacker/maker community to lose two people that seemed like such talented, intelligent individuals.

Condolences for sure. Do you happen to know the size of their place by chance? CO becomes deadly at about 400 PPM or 0.04%. Doing the calculations I can't for the life of me figure out how a small laser cutter could produce enough CO under any condition to become deadly. Even with the smallest of places, lets say 24x20x7 studio, that's 3,360 cubic feet of air & at 0.0807 pounds per cubic feet of air, that means roughly 271 pounds of air. To become toxic, that would mean the laser cutter would need to output 0.1084 pounds of CO or roughly 1.7 ounces of CO in that area and then not get dissipated through air leaks, opening and closing the exterior door, etc. That seems exceedingly high given a laser is going to cut very little actual material and even getting to the point where it has cut 1.7 ounces of material, let alone produced 1.7 ounces of CO would seem to me to take weeks, months, or years.

Based on public records, appears the building is a fourplex and the total floor space for the building is 3328 square feet; as such, my guess is the their unit was 832 SQFT. Room height based on exterior photos roughly appears to be 8-10 ft.

Deep condolences to you and to their friends and families. x

I knew Roger through a meetup group and a mutual friend. I'm sad that our community has lost such a bright and talented person. He was a big inspiration and will continue to be. I'm glad to hear that people are mobilizing to keep Shard going.

I'm very sorry for your loss; what a terrible tragedy.

Do you think there's even a physical possibility with the material used with printers ?


No, not possible. With the added clarification on the apartment size a laser cutter would have had to have output nearly 1/2 pound of CO. My initial 1.7oz calculation was absurd in thinking that amount of CO could be produced and at 1/2 pound, it's not even worth entertaining.

Could CO be produced by a clogged clothing dryer?

Small datapoint: Gas dryers are pretty rare in the US, but do exist.

CO poisoning is cumulative. It takes a long time for CO to get unstuck from hemoglobin. (About 2 weeks, IIRC.) It could have snuck up on them slowly, then one evening with the cats "napping" they felt particularly tired and thought to themselves, "We must be in hibernation mode from the chilly weather," then they went to sleep then never woke up.

CO is odorless. You might get a headache, or you might only feel tired. What's worse: a lot of cheap CO detectors are pretty shoddy.

To add to this, here's a really interesting story of someone who thought that his landlord was stalking him, but really he slowly become poisoned by a carbon monoxide leak.


He was leaving himself notes which he later didn't recognize, he thought someone was in the apartment! It was suggestions on reddit tnat made him realize it was CO poisoning.

Already knew that story, still crazy.

I recently started getting very interested in air quality in my house. I decided to take a similar approach to air quality that I do with the stock market: lots of small, well distribute bets whenever possible.

For context, our house is 3 levels with a furnace in the basement (cold climate; Canada) I ended up with 3 different brand of CO detectors, 2 different brands of smoke detectors and 1 radon detector.

By far the Radon detector is the most expensive at around $250 CAD, and least critical for the short term (but for the long term concerns, anyone with a below grade section of their home should have one!).

A decent Co + smoke detector (You can often get them in one unit) should cost you no more than $30-40 CAD. Testing a CO detector isn't super easy (not like smoke detectors - just make some well done toast), but I'm trusting that if i have several different kinds well distributed throughout the house at least one of them should save us.

I focused on keeping detectors both near and & inside bedrooms, as well as having a minimum of 1 smoke + CO detector on the other floors in open spaces.

Unrelated to these gasses, I also purchased VOC sensors. These are SUPER interesting. It's amazing how the VOC level rises after a few days, and all it takes is opening a window for a few hours to bring it back to lower levels. We were renovating recently and found that after virtually every contractor the house needed hours of windows open to bring the VOC level back down to something that the sensor considered "good quality" (lower than 450 ppm).

Hope that random rant was interesting to someone :)

Which VOC detector do you have?

After I purchased my new house (USA, Georgia) I put in the detectors. My wife is from China where people are rightfully paranoid about formaldehyde - due to low quality building material. It's basically the same in the USA, except people are a lot less knowledgeable and informed about it. My cabinets, drywall, paint all had high level of formaldehyde. Had to always had the windows open...otherwise it would rise above OSHA approved levels.

In the USA, there's no regulated levels for residence..but there is for office. Funny, isn't it.

Eve Elgato: https://www.elgato.com/en/eve/eve-room

Sadly they do not break it down by substance type (which the website almost suggests it does), but i find it very interesting to monitor and that the measurements are highly correlated with painting or opening a window.

Dang! Eve looks good, especially for the price.

I have Foobot (https://foobot.io/) and looks like it cost twiec as much as eve but probably does the same thing. Though, it doesn't say if eve uses wifi..I just see it say bluetooth. I like how Eve is battery powered, you can bring it wherver you want - whereas Foobot is plugged in.

I have UNI-T UT-338C for on the fly readings. I like how the UNI-T can be portable, or plugged in and has a display. I get similar readings between the UNI-T and Footbot so I can somewhat trust it...

It's really rather decent, but I grow to hate the HomeKit protocol more every day (slow, buggy and not something I can mess around with) probably a wise move not going with something apple powered.

Which one do you have that breaks it down by substance?


Volatile organic compounds (VOCs) are organic chemicals that have a high vapor pressure at ordinary room temperature.


Oh jesus. I'm currently renovating 2 bathrooms at once and ceramic dust is coating pretty much everything else not secured. I didn't even know about VOC's until now. I may have to invest in a detector

EDIT: I ended up ordering a Foobot after doing some homework

Oh I feel your pain. We renovated our basement and did a polished concrete floor. Brutal dust, it's just everywhere and I've tried to clean so many times but a few days later I look under something and BOOM missed a spot, it got everywhere! Masonary dust is a special kind of horrible.

Was very interesting to me!

I'm curious what options are out there that will connect via something like RS232 or USB and let you tie into a centralized logging system (which would be incredibly easy to build). "Windows app with one-click data export" would be nice but isn't quite the same as a realtime feed.

The main question would be whether polite pokings would produce protocol documentation, if this isn't already shoved in a forgotten corner on the website (or something).

I have a fascination with CO poisoning for some reason or at least the chemistry behind it. CO has more than 200 times the affinity for hemoglobin than oxygen does.

You can't just go outside to get fresh air since the CO just won't let go.

I believe the normal way it works is oxygen and carbon dioxide use different sections of hemoglobin molecule so they never interfere with the way each are transported. But CO hogs it all oxygen has no chance of affixing to hemoglobin since there is nowhere to stick.

> But CO hogs it all oxygen has no chance of affixing to hemoglobin since there is nowhere to stick.

CO's action is not purely competitive. Its binding at one binding site influences the three other sites to bind oxygen so strongly that oxygen won't dissociate from the complex where it is needed; In tissues, starving them of oxygen.

> You can't just go outside to get fresh air since the CO just won't let go.

Yes you can...


Emphasis on "just". Yes, obviously getting fresh air is an important step when you suffer from CO poisoning but it's not sufficient. Even the site you linked to mentions you should get additional treatment.

Intuitively most people would think that just stopping to breathe CO is sufficient and breathing fresh air would displace it as quickly as with other common gasses (i.e. you may cough for a bit but recover in minutes) but the point is that CO is clingy.

EDIT: Elsewhere you agree with the assessment that the half-life under "fresh air" is somewhere around 4 hours, so I think you would agree that "just breathe fresh air for a bit" (implying minutes, maybe an hour) isn't a satisfactory treatment in serious cases.

3-4 hours is "a bit" when compared to the multiple weeks the GP suggested...

You should absolutely seek medical treatment if you suspect you have been exposed to CO. I'm not trying to make light of that. My point is simply that CO is not actually as "clingy" as some in this thread are making it out to be.

I am a paramedic. We carry a portable CO meter on our "BLS bag" (the bag that gets brought in on the vast majority of calls), because more than once a "general illness" call has turned out to be CO poisoning.

>We carry a portable CO meter on our "BLS bag" //

Do you carry other equipment for personal protection like that (or the long version - what's in the bag!?)?

"Standard" PPE (personal protective equipment) is basically our standard uniform[1], plus nitrile gloves and a radio. Additional levels of PPE include safety glasses, gowns[2], and full face shields. We also carry ballistic vests in the event a potentially violent scene.

We are a combination fire/EMS agency, so I am also a firefighter, with all the gear that goes along with that.

As far as the bags go, we have three main bags:

-The "BLS" or "Airway" bag, which contains a lot of "basic" equipment (bandages, oxygen, some common meds, etc), as well as more advanced airway management equipment (laryngoscopes and endotracheal intubation tubes, etc).

-The "ALS" or "Med" bag, which contains all ~30 medications we carry, as well as IV fluids and all the necessary pointy things to get medications into people.

-The "Pediatric" or "Peds" bag, which contains most of the same stuff as the other two bags, just in smaller quantities, and sized for kids.

There are also a few other more specialized bags (the burn bag, the trauma bag, etc), and portable equipment (portable heart monitor[3], suction[4], etc)

[1]: Stock photo of a standard "class b" uniform: https://www.lansinguniform.com/wp-content/uploads/2014/05/Fi...

[2]: https://www.spservices.co.uk/images/products/pics/1407156050...

[3]: http://www.physio-control.com/ProductDetails.aspx?id=2147484...

[4]: https://www.boundtree.com/s-scort-iii-suction-unit-596400-ph...

"After the patient has been removed to a safe area, it is important to immediately begin administration of high concentration oxygen to maximize hemoglobin oxygen saturation. Treatment and monitoring of the patient with CO exposure should continue on scene and en route to the hospital. Continuously monitor SpO2 and SpCO levels, obtain a 12-lead EKG and monitor the ECG en route. Remember that SpO2 monitoring alone is unreliable as you may get a falsely normal reading in the presence of carbon monoxide poisoning."

As with all poisons, that depends on the dose... For a low level exposure, fresh air is truly all that's needed.

I'm not trying to suggest that more advanced treatment is never necessary (I am the person who provides that treatment...), my point is simply that there are _many_ people who experience low level, chronic exposures to carbon monoxide that require no further treatment than leaving the environment.

Thanks for saying that, I had no idea CO stays in the body so long. I thought you could just breath fresh air and clear it form your system quickly.

You're correct. Breathing "fresh" air will drop the CO levels in your blood by half every few hours.

A few hours is a lot slower than I'd imagined.

If this was indeed a LASER cutter then you would definitely be able to smell all the other gases emitted with the CO. I've got a small LASER cutter and even with the hose going outside the smell very strong.

One post up above says some of the newer cutters targeted at consumers have carbon filters and exhaust the air directly back into the room. The carbon doesn't capture CO but may capture the odors from other compounds.

So, a bad design that sells well, but hides the important signal.

In case of natural gas, we have long long time ago started mandating odorization (after a lot of silent deaths): https://en.wikipedia.org/wiki/Odorizer

This time, we basically allow laser cutter manufacturers to ignore these lessons (learned with a losses of thousands of lives).

Well we don't know for sure that that was the cause yet.

If it was a progressive build up I really doubt the cats would have died the same day as the two humans. It feels like a sudden occurrence. And like the top comment said: even the CO poisoning is not confirmed yet.

That smells of an easy sensationalist headline there.

Berkeley has been having it's coldest/rainiest weather of the year during the last week. Really heavy rain last weekend. Unlike most of the year where everyone can leave their windows open because the weather is almost always sunny and 70.

They may have had a deadly amount of CO/particulates from their laser cutter in their apt but their ventilation kept them alive. Closing their windows during last week's rain/cold spells could have been deadly. Also there is a possibility of particulate buildup in vents that could have been released if they turned on their heat in an enclosed apartment.

CO leaves you with diminished capability to bind o2, breathing in a small enclosed apt leads to a buildup of CO2. This tragedy could be a combination of CO and CO2 inhalation.

What CO detectors would you recommend?

The consumer ones work fine. They've come a LONG way in recent years.

They may not be accurate but they don't need to be at the levels where CO becomes fatal. It is better to have several inexpensive ones than just one or two $300 highly accurate ones. Since you don't know where the CO will be localised.

You can test them yourself fairly inexpensively look for "HOME SAFEGUARD HO-CO2 Carbon Monoxide Detector Tester, Aerosol." Get a Ziploc bag or similar air tight baggy. Place the alarm in a bag, spray the Aerosol in it, and wait. It should go off in 2-5 minutes. Obviously it is best to do this test outside.

Consumer Reports also tests them:


Omega is one company I would trust for this myself; they sell for industrial applications, not homes, and have a good reputation when it comes to sensors. A CO monitor will set you back $235.


Is there any way to know that an expensive CO detector like this is worth getting for home use, instead of one costing 10x less?

Hard to say, but Omega definitely care enough about their brand and reputation to have a good QA system and testing of products in place. Since testing that a CO monitor is working is very hard for a consumer, you rely a lot on trust in the brand.

If you can get a good, trusted brand for home CO monitors, I'd say go for it.

Apparently, Kidde is a trusted brand in fire alarms etc. in the US, so I think this one ($20) is probably equally trustworthy:


Anecdotal: I've bought cheap versions of things online enough times that I don't want to do it again (just got home from helping a friend install a battery that didn't even fit properly). I've had a few things melt and a couple explode..

I shudder to think that you would risk your life on a device of questionable quality.

>I shudder to think that you would risk your life on a device of questionable quality. //

The problem is surely knowing whether the expensive equivalent is just the same internals in a different retail pack (with other 'quality' signalling). That's genuinely hard for something that needs a lab to be tested.

A CO "monitor" is permitted to alert at low levels of CO (10-20 ppm). A UL-listed code compliant CO alarm may not. I personally think this is silly.

There are a few companies that sell low level CO monitors for residential use. They're all somewhat pricey.

  A CO monitor will set you back $235.
$235 sounds (relatively) expensive. I recently replaced the 3 CO alarms in my flat - they cost me around £23 (29 USD) each [1].

[1] http://www.toolstation.com/shop/Electrical/d190/Carbon+Monox...

Are there any that work in temperatures below freezing? I'm living in my car and using a propane heater when it gets cold.

Wow. That is definitely a recipe for carbon monoxide poisoning. I encourage you to find some other way to survive, because it's unlikely you'll survive long doing that.

If you're able to get a small ceramic heater, you'll find that there are many unexpected places to plug it in. E.g. near gas station car wash exits, some parking lot lamp posts, etc. Check with the owner for permission, there are some that will grant it, especially if you're able to offer some lot cleanup or other bartered assistance for them.

Don't use a propane heater, please. It's dangerous to you and potentially to others nearby.

Source: Been there.

Any off the shelf product should be fine (there are standards they have to meet). Kiddie and First Alert are both well regarded brands.

I use First Alert personally (they have model with Z-Wave integration that ties into my home automation system). We carry a few Kiddie smoke/CO detectors on the fire truck to install if we notice a home doesn't have one (or if the one they had failed).

In regards to the smoke detectors, I love that your department does that! I think what finally drove me to realize how important working smoke detectors are, is that video of a modern room flashing over in like 3 minutes.

For those who haven't seen it, here:


Surprisingly those standards won't allow low levels to be displayed, so that emergency centers don't get too many non-emergency calls.

At his point, I would just pony up some cash. Maybe bug a chemistry geek YouTuber.

I've researched this some months ago, but it isn't a one time cost. I arrived at this model:


But if you want to do it right, you also need a calibration station and calibration gas bottles. It is quite an effort.

[No product placement, also look for Honeywell and others.]

I think CO doesn't get unstuck from hemoglobin at all. 2 weeks sounds about right, in that that would be the body's mean replacement time for a hemoglobin molecule.

The normal half-life of carboxyhemoglobin, when the patient is breathing room air, is 240 to 360 minutes (4-6 hours). The half-life of COHb can be decreased to 80 minutes with the administration of 100% oxygen.

It can be brought down even faster with hyperbaric oxygen therapy. Hyperbaric chambers are reasonably common, due to usage in both (SCUBA) diving related medicine and various therapies for wound care.


>It can be brought down even faster with hyperbaric oxygen therapy.

What's the limit on that? The link you posted says 2.5 atm of pure oxygen but how does that not cause oxygen toxicity?

According to the toxicity curve from wikipedia, even at 2.5 bar, you wouldn't start to see issues until ~4 hours have past. That's enough time to remove quite a bit of CO.


Is there a cheap and high quality CO detector? I think it's time I replaced mine since it's probably way past due.

an addition here - there are two classifications of CO poisoning: acute and chronic. Acute is deadly in anywhere between minutes and hours. Chronic ranges from not deadly to lethal and can be after hours, days, or months of exposure.

>> About 2 weeks, IIRC.

Does the CO actually get out or do the red blood cells die and get replaced?

It lets go on its own. The levels in your blood fall by half every few hours.

5.3 hours.

It's nowhere near that precise a number...

No it's within hours. A simple google search will show you that.

He indicates that the CO poisoning could have been gradual. This is not mutually exclusive with faster poisoning.

Not the point. OP (it could be a woman) said that it takes weeks to unbind when in fact the half life is 74 mins.

Leaving the house for a few hours a day would be sufficient to "reset" the COHb levels in the blood.

I'm seeing numbers like 320 minutes, 5.3 hours. Of course that's only enough halve it, not clear it completely. Leaving the house for "a few hours a day" sounds like dangerous advice to me.

"3D laser printer" probably means a Glowforge. Nobody else calls them that. Their documentation says "Lasers normally require some ventilation via a small tube out a nearby window. Our optional Air Filter that sits under Glowforge and ventilates using HEPA filters and charcoal, meaning no outside ventilation is required." That won't do much if you cut something that emits carbon monoxide when heated. That includes some common plastics, styrene being one.

There are lots of things you don't want to cut on a laser cutter unless you're cutting under an inert gas, or at least nitrogen. Polycarbonate, any of the chlorinated plastics (PVC, some synthetic leather), styrenes, and polyethylene, for example. ABS melts, and Fiberglas's glass component won't cut. Acrylics cut very well. Delrin cuts OK. Wood and cloth are OK. Techshop is careful to teach people about this.

TechShop's laser cutters have compressed air coming in, a big exhaust hose going out, and a fire extinguisher nearby. TechShop has an ad slogan, "Don't try this at home. Do it at TechShop". There's something to be said for that when you're using industrial-strength tools.

In addition to the two people, their two cats died. Operating these things in a closed room is a really bad idea.

I'm the CEO and cofounder of Glowforge - we're so saddened by this tragedy. Our product was not involved, but that doesn't make us feel any better about this loss.

If you use a laser, ours or anyone else's, please go back right now and re-read the safety instructions. Accidents like this should never happen. My heart breaks for those affected by this.

OK, it's good to know it wasn't yours. Thanks.

It would be appropriate to put a CO detector in your units before somebody does that with one of yours. That definitely needs to be in the "filtered" units that are supposed to operate with no ventilation.

Might be worth editing your original comment to remove the suggestion that it's a Glowforge, just to avoid unnecessarily associating a specific company that wasn't involved in this tragedy.


Then say something like "means things like the Glowforge", instead of "probably means a Glowforge". One denotes membership in a certain class, providing an example.

The other unambiguously suggests the example is the culprit. And as other posts in other threads suggest, the printer, whichever brand, being the source of the CO poisoning isn't even certain.

I don't work for Glowforge, and you may note my other comment in this thread, which could be taken as critical, so I'm not biased or trying to spin "damage control". And yet, I too think the thread's root's language could be more precise.


You're not supposed to accuse people in threads of astroturfing or shilling. If you have evidence it's best to email it to the mods for them to take action.

Even if it is damage control, it's a legitimate request if any. Their brand could be damaged by mere speculation, especially in this case where it involves a founder who seems safety conscious and most likely an ally for people who care for user safety.

This feels like the aftermath of the exploding hoverboards. Some products are safe but the standards are so inconsistent that the reputation of anyone building them will suffer equally.

Personally I hope the cause wasn't a laser cutter, this could really hurt a young and fragile and mostly innocious industry :(

Yep, looks like PR. nickrivadeneira's account is 4.5 years old and has commented 4 whole times.

Are there CO detectors to buy to react before it's too late ?

Many smoke alarms also measure CO now.

Even if there were smokealarms with CO dedection it's really bad practice. Carbon monoxide dedectors need to be installed on to walls 100-150cm from the floor. In the bedroom I would recommend the height of bed. The reason for all that is the fact that CO molar mass is really similar to air molar mass AKA "that shit will reach the sealing when you're long dead".

Sorry, but what are you talking about?

Yes, CO is similar to air's molar mass (it's actually slightly lower), meaning it will diffuse evenly through the vertical space in the room. The concentrations at the ceiling will be the same as the concentrations on the floor.

Stop spreading misinformation.

But if sources are at human head level, by the time it reaches the ceiling, you already inhaled a fair amount of CO ? what did I get wrong ?


Diffusion of gasses in the air is an extremely rapid process. In a minute the concentration would be the same throughout the room.

I found this paper that directly tested different positions of detectors:

"Should the placement of carbon monoxide (CO) detectors be influenced by CO's weight relative to air?"


Their conclusion agrees with you completely:

What does this say about the placement of residential CO monitors? It would be reasonable to place them anywhere in the room and expect them to be effective. Every scenario imaginable in a home would only speed the mixing of the gas within a real room, as compared to a sealed chamber — people walking, forced air flowing from vents, CO entrainment with warm air being released into a room at floor level and then rising.

The belief held by many that CO sinks is clearly wrong. Statements such as ‘‘Carbon monoxide is heavier than air, and will pool in lower areas’’ need to be refuted with facts (5). Even if CO were significantly heavier or lighter than air, it would still distribute equally from ceiling to floor.

On the other hand, they did find that the rate of diffusion can be much slower than "in a minute":

The time required for the equilibration of CO concentration was different depending on the level of infusion. It occurred most rapidly when CO was introduced in the middle of the chamber (2 min), at an intermediate rate when introduced at the bottom (40 min), and most slowly when introduced at the top (105 min). Nonetheless, the ultimate concentration was equal throughout the chamber, with no suggestion of any pooling on the floor, layering in the middle, or floating on top.


The air filter costs an additional $750 extra when you buy the $3000 Glowforge, I could see students skimping on that and no realizing the implications. https://glowforge.com/order

That said I watched the video for this product and I'm really looking forward to when these are widespread. It's a very exciting industry. I'd definitely buy one of these when it gets to around $1k.

> I could see students skimping on that and no realizing the implications

They weren't students. Roger was a game developer while Valerie was a post-doc. They just happened to live in Berkeley.

Why are we talking about the air filter? a) whether it was a glowforge system is still speculation b) air filters do not have anything to do with CO, only particulate.

The order page definitely doesn't have any warning about the basic - even I would go 'Nah, what's the $720 for? Upsell?'

How about:

Glowforge Pro + Air Filter: $5,995.00

Glowforge Basic + Air Filter: $3,745.00

Glowforge Basic: $2,995.00 Warning: You may die when using Glowforge inside without Air filter (link). You may also die when cuting these materials (link) inside even with air filter.

And all come with 2 co detectors, internal and external

Selling the product without that filter could be considered immoral.

Yeah, in my lab we prohibited cutting anything with chlorine, including PVC and polycarbonate.

The results are really bad anyways, it melts and burns. I'm curious though, can you get good cutting of polycarbonate using an inert gas shield? That would be interesting.

CNC zone reports that cutting polycarbonate on higher power lasers under nitrogen can be made to work, but it's touchy.[1] The plastic tends to melt rather than cut. Pre-freezing the material is suggested.

[1] http://www.cnczone.com/forums/general-laser-engraving-cuttin...

Polycarbonate has no chlorine.

Their laser printer was stored/run in their closet. They may have been doing this for a while with no problems because Berkeley is so nice and everyone leaves their windows open.

Berkeley has been unusually cold/rainy this last week and I'm guessing they sealed up their apt and didn't realize how dangerous that was.

I wonder if a catalyst converter would help.

This is so tragic. I used to work with Roger and he's about as gifted of an engineer as I've ever met. He was so nice and helpful too, even though he was miles beyond me in terms of skill.

He was so into his indy game, Shard, and even whipped out his laptop to show me and started explaining intricacies of the renderer when I met him at an industry event years later.

I didn't know his wife, but from the things I've read she was also a pioneer in her industry. Rest in Peace.

I've always been wary of 3d printers and laser cutters because of indoor air pollution & VOCs. Though I didn't realize the amount they put out and the cumulative effects of CO as mentioned in the comments here.

My sense is that laser cutters should be required to come with CO detectors, and more generally we should be looking to add the appropriate chemical detectors to 3d printers and laser printers to warn of other chemical output issues. These home machines are often advertised for use in confined spaces (size is one way manufacturers compete), which is why I think it should be regulated - its not like someone took a commercial machine home with them. Laser cutters are a fairly large capital expense and bolting on a CO detector is very inexpensive (probably <1%), and it could integrate with the cutter's electronics to prevent usage if it exceeds a certain level.

Safety regulations are usually written in blood. Having two deaths with such a small # of these machines out there suggests there are probably others who have cumulative CO effects already. Very sad, my heart goes out to the friends and family of Roger & Valerie.

Tragic. Recently California started requiring carbon monoxide detectors in most homes.[1] Make sure you have one.

That's a surprising cause though. How much CO can a laser printer/cutter produce, worst case?

[1] http://www.ci.berkeley.ca.us/Planning_and_Development/Housin...

New York has a similar law: http://www.amandaslaw.org/

As both a maker and a firefighter, I would be _very_ surprised if CO from a laser cutter was actually the cause here. Laser cutters can absolutely emit harmful fumes, but CO needs to be in the hundreds of ppm range to be fatal, and that's a _lot_ of CO.

For context, we had a call a while back where a guy was running a gas powered (two-stroke) rotary saw [1] for a couple hours in a poorly ventilated basement. CO levels were in the 300-400 range (and he was certainly feeling poorly).

[1] Something like this: https://www.fastenal.com/products/details/0804841

My dad mentioned that he almost died from a wall heater in college. He was 'sick with the flu' and getting worse. One night laying in bed the wall heater fired up. He saw the light from the flame flickering on the floor and he thought 'that's odd it's orange not blue'

The exhaust was blocked with soot.

I also had a friend and his GF that died from an improperly installed furnace.

I also wonder about cyanide from cutting plastic as well as carbon monoxide. No idea, but they both seem about as toxic.

Roger and Val’s friends are trying to raise money to offset the family’s costs for traveling to the funeral and making funeral arrangements. Contributions can be made online:



"According to a study completed by a team at the Illinois Institute of Technology, typical desktop 3D printers emit particles and compounds during printing that federal agencies say could cause cancer or other ailments."


Though this is marketed as a "laser printer" its most likely a laser cutter. Glow forge was the first I know of to start this stupid fad of calling them printers to be associated with the 3D printer market. Laser cutters burn materials at high energy and need to be properly vented.

Exactly. This was more like having an unventilated fireplace in the house, except it makes much less smoke so you don't realize just how dangerous it is.

At this point living seems to cause cancer...

I mean....it does

That's an especially asinine comment given the clear cause and effect on display in this case.

Makers are often exposed to many toxic compounds, from toxins in salvaged electronics to PCB etching compounds to lead solder and solder fumes. Unfortunately, they rarely have much if any safety training or awareness of the dangers they are exposing themselves to.

As a new hobbyist in the Maker community, are there any resources you'd recommend that covers basic safety that is aimed at Makers?

edit: typo

I'd start with digging up the material safety data sheets (MSDS)[1] for all the compounds you're working with, and reading over those.

I'd also search around for books and papers on electronics safety. It's really amazing just how little electricity is required to stop a human heart, if the conditions are right.

The same goes for chemical safety. College level textbooks on these subjects tend to at least give a decent overview of the issues involved, to a more thorough degree than books targeted at a popular audience. But I wouldn't stop there, and would try to find some more specialist literature dealing with safety in particular.

I'd also encourage you to take courses in these subjects, and talk to the professors about your interest in safety. Unfortunately safety is not a very sexy topic, and tends to get glossed over a lot. But you'll still be far better off with guidance from an experienced instructor than trying to go it all on your own.

[1] - https://en.wikipedia.org/wiki/Safety_data_sheet

The trouble with MSDS is that the lawyers have got to them and they all end saying the same thing (look at the one for salt [1]) and so people become blasé about the really dangerous risks.

When I was an academic I had huge problems with students working with the truely dangerous chemicals in an unsafe manner because they couldn't tell the difference. I had to run little informal classes with my students where I would teach them which chemicals they had to worry about and which were not that dangerous.

1. https://www.sciencelab.com/msds.php?msdsId=9927593

> Do not ingest.

> In case of Skin Contact: Wash with soap and water. Cover the irritated skin with an emollient. Get medical attention if irritation develops. Cold water may be used

Okay, you’re right, these are overly alarming.

You should see the MSDS for dihydrogen oxide [1].

1. https://www.sciencelab.com/msds.php?msdsId=9927321

Okay, I have to respond because there is a lot of misinformation flying around.

MSDS's are good, but you'll go nuts trying to accommodate all of them.

1) Safety glasses. Safety glasses. SAFETY GLASSES. I can't mention this enough. Most injuries can be adjusted to accommodate--losing your eyes isn't like that. And, if you're using one of the more powerful lasers, get the specialty glasses for that.

2) Soldering doesn't really vaporize lead. There are other nasty things in the flux and board (Chlorine radicals are particularly bad). Keep your area ventilated and try not to inhale stuff. Fume hoods are excellent, but nobody I know who does this ever used one. An open window or open garage door generally is good enough for soldering.

3) Use leaded solder. Yes, I said it. Lead-free solder sucks to work with by hand. Lead-free solder takes a lot more heat and vaporizes more garbage than leaded solder, not less. One of the best ways to desolder lead-free solder is actually to add leaded solder and then desolder the result since it now melts at a lower temperature.

4) Too many people store their solder paste in the same fridge with food. That's a problem. Solder balls get everywhere very easily.

5) Arc welding is nasty. Old school shielded metal arc welding (stick welding) vaporizes all manner of nasty stuff. Use MIG or TIG instead--they still vaporize stuff but way less. They're better welds anyway. Also be careful about welding things like galvanized steel.

6) Hearing protection. You need it more than you think you do. I have hearing loss from years in server rooms in the 1990's.

7) Respect even the small machines. A small milling machine or lathe can't take off your hand as quickly as a radial saw, but it can still maim you quite badly.

8) Respect anything with a cutting edge even if not powered. Sure, an unpowered cutting edge probably won't kill or permanently maim you, but that doesn't mean you can get careless. I see people change milling bits without wrapping the bit in cloth while they hold it all the time. Generally, those same people wind up with scars across the palm of their hand. I suspect the lowly utility knife causes more injuries than any other tool.

9) Powders are really damn dangerous. In addition to being highly flammable and explosive, they get in your lungs and don't come out easily. Sawdust from real wood is bad--sawdust from particle board is worse. It has all manner of nasty shit in it.

10) Volatile organics are worse than you think. Acetone, kerosene, paint thinner, etc. do nasty things to you. If people can use it for "huffing", it probably is nasty to your brain. Ventilate these things much better than you would for everything else.

Ventilation, eye protection, hearing protection at all times when appropriate. Rig a fume hood.

I think the question Steezy was getting at is, yes, those things are great. What kind of ventilation? Can I 3d print in the garage if the door is open? How much air is required to make it safe?

Is there a simple way to lookup a material and make sure you're using the right safety precautions? Most materials seems to carry the "will cause cancer, sometimes, maybe, always" label.

Is there a modern "maker" safety course, covering things like 3d printing, laser cutting, glues and paints, electronics, etc. that I can follow?

get a fume extractor if you solder, and especially if you desolder old boards. then, only solder with lead-free solder.

Ever done an undergraduate organic chemistry lab? You're exposed to far worse, I assure you.


Unclear what a "laser 3D printer" means--possibly selective laser sintering, but that doesn't produce carbon monoxide to my knowledge. Possibly a homegrown machine. Tragic reminder of the importance of proper workspaces.

Glowforge marketed their laser cutter as a 3D laser printer, didn't they?

As someone waiting for their Glowforge to ship, I really hope their device wasn't involved in all this.

From Glowforge's website, for their base model:

> It needs ventilation via the provided 4″ diameter (10.2cm) hose. We recommend putting the hose out a window.

They also say:

> Lasers normally require some ventilation via a small tube out a nearby window. Our optional Air Filter that sits under Glowforge and ventilates using HEPA filters and charcoal, meaning no outside ventilation is required.

Best to my knowledge HEPA and charcoal don't help against CO. So running one with the filter in an unventilated space might still be hazardous.

"To qualify as HEPA by US government standards, an air filter must remove (from the air that passes through) 99.97% of particles that have a size of 0.3 µm."

Carbon monoxide is a few orders of magnitude too small to be caught by a HEPA filter, in fact a filter that could filter CO would filter oxygen and nitrogen as well. Such a filter would just be a pump.

There, however, exists a patent for a filter for CO, it works by converting the CO to CO2: https://www.google.com/patents/US5564065

Needing to eliminate CO is an old, well-solved problem. Even the cheapest catalytic converter would do so.

(It's not quite as simple as just putting one in-line with the waste gas flow- the catalyst would also need to be externally heated.)

It is possibly to filter gases of similar molecular weight. https://en.wikipedia.org/wiki/Membrane_gas_separation

This technique is routinely used to generate concentrated supplies of oxygen or nitrogen, but is wildly expensive compared to ventilation.

I'm guessing this is undergoing a hurried rewrite, to add something along the lines of 'or you may die.' they're gonna get sued out the yin-yang for this even if the dead couple totally ignored the instructions, on the grounds that the instructions didn't state the danger clearly enough.

Having said that, while good safety information is important, two MIT-trained engineers should really have known better.

Why should they have known better? He was a software engineer and she may have had exposure to lab technique but a Glowforge doesn't scream "needs an industrial hood" or anything. Yes, they clearly _could_ have known better, but 'should' seems to be making too-strong assumptions about their class work, MIT or other. They could have had economics degrees for all we know (less likely given their careers, but you get my point).

Yeah, while I get that the general public misses this, I'm surprised to see people who apparently think that "engineer" means a Star Trek-style omnicompetent generalist.

I dunno man, if something says you need to ventilate it by putting an exhaust hose outside, I figure there must be a good reason for that. I have a lot of hazardous chemicals in my house because I paint and a lot of artist paints have toxic ingredients. I read the safety warnings carefully even though I know little of chemistry.

It says you don't need to vent if you use the filter.

I read the safety notices that manufacturers affix to their products and take them at face value unless I have reason to believe otherwise. It seems kinda stupid not to.

And it said you don't need to vent if you use the filter.

Glowforge company is upthread, says the deceased were not customers of theres. Presumably it's a different brand of laser cutter.

That said, I'm assuming Glowforge is going to scramble to make sure that users use their device safely regardless.

... while all their marketing materials and videos show Glowforge sitting happily in the middle of a living room with absolutely no exhaust pipe.

I think the bigger issues is that these kinds of DIY maker tools are marketed as in-home. You wouldn't put a band saw in your spare bedroom-why do people use these kinds of tools in a normal house/apartment? Though two engineers living in Berkeley are probably not going to have a garage, alas.

Might be a laser cutter/engraver. Would make more sense since those actually do burn the material.

I don't know anything specific in this case (I have been following it since it was first reported, since it's local, and mysterious). But my first suspicion would be the CO2 gas supply to the laser. Low-quality CO2 gas has CO impurities. I think a leak in the gas supply, combined with really poor ventilation, could possibly lead to this situation, but I'm still surprised there would be enough CO to fatally poison 2 people and 2 cats.

The CO2 laser tubes sold to hobbyists are sealed. There is no gas supply. Large industrial lasers use a gas supply in order to cut faster and at higher power.

Some home-built tubes do use a gas supply, but virtually no one builds their own CO2 tube to use in a laser cutter when better tubes are available on eBay for $100.

I never said anything about the laser tube. I think it's more likely they did use a gas supply and that leaked.

I've never seen or heard of a non-industrial laser cutter with a gas supply.

Air assist, yes (to clear smoke and particles from the beam and protect the focus lens from soot), but that's just an air pump, not a gas supply.

What would you use a CO2 supply for with a laser cutter or 3D printer then? I can't think of anything.

Maybe I misunderstand how CO2 lasers work. But my understanding is that a high-powered CO2 laser can be run using a gas supply from a tank/regulator. As mentioned elsewhere, this is typically only done in industrial settings, but some home laser cutting enthusiasts want more power. The tank contains some mixture of gases, primarily CO2, but containing other gases, likely some CO. If the tank/regulator to laser tube connection is leaking in a closed room, then the CO concentration in the air will increase.

This is speculation on my part based on my assumptions. If my assumptions are incorrect that's fine.

Yes, but those would feed CO2 into the laser tube, which I thought you just excluded ("I never said anything about the laser tube.").

As others have said, normal laser cutters have sealed tubes, although its of course possible they had some DIY rig for whatever reason. MIT students building their own CO2 laser just for fun doesn't seem all that odd, using it for long time in a cutter maybe more so. I don't know if a leak in a CO2 system would lead to CO poisoning or no. CO produced by the material cut seems more likely to me.

Sorry, I guess it is a bit unclear: I assumed the leak preceded the laser tube proper. When you hook a tank/regulator up to an evacuated tube, there can be leaks "before" the laser tube (I spent a month building vacuum chambers, and most of my leaks were in the connections between the vacuum pump and the chamber, not the chamber itself).

however, after thinking some more, I agree that CO from material cut is more likely.

The "gas supply" you're referring to is most likely an "air-assist". Laser cutting works better when you have a flow of air (just air), blowing the smoke out of the way.

Many folks use small compressors for this purpose.

But it won't have anything to do with CO levels.

CO poisoning is cumulative. It takes a long time for CO to get unstuck from hemoglobin. It could have snuck up on them slowly, then one evening with the cats "napping" they felt particularly tired and thought to themselves, "We must be in hibernation mode from the chilly weather," then they went to sleep then never woke up.

CO is odorless. You might get a headache, or you might only feel tired. What's worse: a lot of CO detectors are pretty shoddy.

Your description makes me increasingly worried; do you have any preferred CO detectors?

Avoid cheap ebay stuff. I think Consumer Reports have done a rating of those devices sometime. However, that might be out of date at this point. I just did a search on YouTube, and even those random reviews seem to date from 2014. There should be a way to verify those. Maybe Cody's Lab could handle this?

Co2 lasers are 30℅ CO by design. Kind of like a halogen cycle thing but recombinant.

There is very little gas in a tube though.

It seems the poisoning came from the operation of the laser, which means that the gases inside the laser were not involved. (It doesn't seem from breakage of the tube, but from usage.)

at other sources it is said that they had "laser cutter and 3D printers".

PSA: Make sure you have carbon monoxide detectors in your home, and that you replace them every 5-7 years, as the detector goes bad over time. If you are in a home with a high chance of carbon monoxide buildup, get one with a digital display to help first responders understand your exposure level. if you have children, get one that talks.

This is horrible.

Anyone with combustion sources of any kinds (gas heat, cooking, cars in a garage, many kinds of tools) should have a CO sensor properly placed. I'm staying at someone's house for a month, don't see one, so I just ordered a couple.

I installed two carbon monoxide detectors at my mother's house over the holidays and really we all should, it's not a big cost. This is very sad for their friends and family but most of all for the poor couple. I think it's selfish but rather human to say that when something like this happens to 'people like us', in this case referring to background, interests, and hobbies it can feel extra shocking and upsetting.

We've had so many fire false alarms but finally a real one happened. It was raining hard and maintenance closed the top vent to deter water intake. The unit is a 4 story multi-unit dwelling and luckily someone had a cheap $49 dollar CO detector. The fire came sans alarm and everyone had to evacuate. We were thinking ah man not this again. Someone had some burnt cooking that day. We could only return to our homes until all clear CO detection from the inspectors. My family opted in for the pulse oximetry that the nice fire folk were providing. Needless to say many, including myself, bought CO detectors that week.

Everyone should read this, and forward to their loved ones. This is very close to home (not literally) because it could happen to anyone, and is something that many people do not consider. Have up-to-date CO detectors, do not operate large appliances without considering their byproducts. Literally, the environment matters more than anything, and this acts as a grave reminder of this. Take care of the environment, especially the tiny one in your home, as it could save your life.

towngas or coalgas that is piped in for cooking is hydrogen and carbon monoxide, has all the other possible sources of carbon monoxide been ruled out before nailing it on the laser cutter or 3d printer? https://en.wikipedia.org/wiki/Coal_gas

i'd prefer it that the 'authorities' do a thorough and scientific investigation and release the results in public on the internet, this needs to be proven beyond all doubts that it is caused by the laser cutter or 3d printer

if this is not done, it would stir worldwide unnecessary panic about laser cutters and/or 3d printers by saying that laser cutters and/or 3d printers produces carbon monoxide and is dangerous and hence cannot be used

i'm not sure about laser cutters but normally 3d printers is more a fire hazard than do anything else, i.e. 3d printers main hazard is fire, but carbon monoxide is likely 'fake and invalid/assumptions/speculations'

That's tough. Operating any sort of industrial equipment gets dangerous very fast; I know a plaintiff attorney who handles cases like this (injury due to improper exhaust), and the fact that it's actually an area of practice tells you something.

Hi, i've a co2 laser cutting (40w) idle all the time (i do not use it anymore) since around one year in the room close to my bedroom. even when idle its dangerous ? i really don't know what to do, what do you suggest me guys. thanks in advance

I lit a candle last night with a closed window and door. Then it hit me that there is no way there is no CO in this room. Immediately opened my window. After hearing this story, I am never sleeping with my window closed.

With one candle, you're in far more danger from it tipping over than from CO.

Yeah, I don't leave the room without the flame completely out.

I'm not sure about candles, but a decently oxygenated open flame (e.g. your stove without a pan on it) emits essentially no CO.

Getting a CO detector seems like a simpler solution than keeping your window open forever.

Are you trolling a dead couple? A candle's CO is what you are worried about? Sigh.

> After hearing this story, I am never sleeping with my window closed.

no fans either, just to be safe.

Very, very sad. Who knew that it created CO, but I have paranoia about stuff like that so I would only have it in the garage. Maybe that wouldn't be enough depending on how much CO it produced.

The hazards created by this type of equipment are well understood [1]. The problem is that many people do not know about, and are ignorant of those hazards.

[1] https://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_6.html#2

Might as well raise awareness of Radon, and laser printers.

It's a tragedy, and reminded me of Marie Curie (who eventually discovered her research was causing damaging levels of radiation exposure).

Damn, I need to invest in some CO sensor. Very sad to read.

Having tried one, I wouldn't trust a detector. That was money not well spent. I could generate lots of CO, and nothing would register. Maybe flawed units are super-rare, but I'm more than tempted to assume the industry is a fraud.

Why even bother? The device has one job, and it fails. All you get is a false sense of safety.

What most people miss about CO detectors is that they don't go off until CO levels have been elevated for a while. At low concentrations it can take multiple hours to trigger the alarm; at higher concentrations it can take 30 minutes. Even at dangerous concentrations it can still take 5 minutes to sound the alarm. So you can hold your detector in front of an exhaust pipe for a minute and it won't go off, but stick it inside an upturned pot with a candle inside and it will definitely go off eventually.

The reason for this is to prevent common false alarms like CO emitted due to cooking or smoking.

Depends on the type of unit you had. A "sensor" certainly should have picked up lower levels, but most "alarms" don't go off unless harmful limits are hit - often calibrated at or above 100ppm, depending on the unit specs.

Roger was an inspiration to me. Now he's dead.

This is as tragic as it gets, I suspect liability will fall onto whoever made their "laser 3D printer" if the ventilation warnings weren't good enough.

do you have any news?

Hi folks. Val and Roger were dear friends, and I am on the ground here, and I'd like to respectfully ask that you refrain from speculation. The press is rushing to print sensational items, and they don't know the actual facts.

I've been talking to the police directly, and nothing is conclusive yet. They don't even have full toxicology reports.

On a personal note, I can tell you that there were two devices in the house, a small 3D printer, and a small laser cutter, that were used for building models and rigs for scientific research. Val was an immaculate engineer, and conformed to all safety rules in operating these machines. To the best of our knowledge, neither of the machines were operating the night they passed away.

Again, please refrain from fear-mongering and speculation. I know it's natural for engineers to attack unsolved problems, but you are not working with correct or full data. Once more data is available, we will write up a complete and truthful statement to try and provide closure on this issue.

Article and headline are incorrect: "Carbon monoxide poisoning has also been ruled out."[1][2][3]

Both MIT grads; one a founder of gaming company Glug Glug[2] and co-author of game Shard[4]

1. http://www.eastbaytimes.com/2017/01/25/berkeley-toxicology-t...

2. http://kotaku.com/game-developers-mourn-sudden-passing-of-ex...

3. http://www.sfgate.com/crime/article/Two-people-found-dead-Be...

4. http://shard-game.com/

The articles you linked are older (24th & 25th) than the article from the headline ( January 27, 2017 2:15 PM ).

Further investigation and toxicology reports revealed carbon monoxide (fixed) poisoning. It appears the initial statements ruling out carbon monoxide poisoning were in error.

CO or CO2? Both are possible, CO2 poisoning is quite horrible though, whereas CO poisoning may go unnoticed.

CO2 poisoning is insidious, and can go unrecognised, due to its cognitive effects. It's a known risk in using rebreathers when scuba diving.

The UK HSE has published a video of a real-life incident where someone experiences CO2 toxicity from a rebreather (the victim survived and recovered) [1].

[1] http://www.hse.gov.uk/diving/video/co2video.htm

Yeah really -- I can't imagine you could die of CO2 poisoning without noticing in time to GTFO. I've sucked a lungful of CO2 and it was awful.

There is a difference between high and low concentrations of CO2 and reactions. In high concentrations you get similar effect to lack of oxygen (as it completely replaces oxygen in the air), in low concentrations it prevents the HbCO2 from unbinding (only 7% of CO2 in air is enough to do that IIRC) and causes silent death. There are stories of miners sitting down for a lunch and never standing up again because of that.

Carbon monoxide is "CO". CO2 is carbon _di_oxide.

Would a laser cutter cause CO2 poisoning?

Very tragic.

All the signs were CO poisoning from the start. I think first responders said the body discoloration looked like that. The "ruled out" is probably just a mangling of: water heater, oven, and furnace all ruled out as CO sources.

> White also responded to media inquiries about a neighbor’s report of the sound of a generator and an odor of burning rubber coming from the couple’s fourplex in the 3000 block of Deakin Street.

Sounds like they were likely running a laser cutter and the "generator" sound was actually an air compressor. (These are used to blow the smoke out of the way of the beam so that you get a cleaner, more accurate cut.)

Chlorine gas is a major risk with a lot of materials, but presumably there could by other kinds of nasty fumes depending on what they were cutting.

edit: others are saying that it was in fact CO, so I'll go with that. I'd still like to know what they were cutting, though.

> White said the police department received a noise complaint on Sept. 22, 2015, and when a police officer later contacted the complainant about the issue, the generator was no longer running.

2015. If that is about the same incident it's quite a while before the current event (unless it's a typo in the article).

Off topic, but I’ve never seen the care-of symbol (℅) used in place of percent (%) before. I’m really curious how that could happen. On my keyboard I can type % as shift-5, but there’s no way to type ℅ without selecting it from a list of characters.

We detached this subthread from https://news.ycombinator.com/item?id=13507997 and marked it off-topic.

On Android, the Google Keyboard has both symbols on the same screen[1], and it's difficult to visually differentiate them. When you see this particular typo, it's probably someone using the Google Keyboard on Android.

[1]: https://www.reddit.com/r/Android/comments/56hwfd/psa_is_diff...

This is a problem on Android devices. The ℅ symbol is above the space bar when switching to the symbol keyboard. With the keyboard font as is, the two look very similar.

How in the hell can a 3d printer produce enough CO to kill people? A shitty woodstove I could believe, or the classic run the car in the garage technique


We detached this subthread from https://news.ycombinator.com/item?id=13509087 and marked it off-topic.

Given that the context is "CEO attempts damage control after being falsely accused of killing 2 people with an unsafe product", maybe this isn't the time?

Is it fair to call the product unsafe? It's industrial production equipment. I think if a person chooses to operate one in their own dwelling, it's on them to take increased safety measures.

Two people are dead and the context you think I was concerned about is some poor CEO playing damage control?

two people are dead, and you want the CEO of a company just accused of contributing to those deaths to talk about your issue with cloud-dependent devices?


You might not want your bot to post in threads like this, which involve the deaths of people known to some in this community.

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