Monday, January 10, 2022

Portable Generators and Carbon Monoxide: What To Do?


In February of 2021, over 200 Texans died when winter storm Uri disabled the power grid for several days.  According to one source, 19 of those deaths were related to carbon-monoxide (CO) poisoning.  If you were one of the fortunate people to either have a portable generator or buy one before the stores sold out and closed, you took the risk that carbon monoxide from it could kill you.  About 70 people every year die in the U. S. when CO from portable generators gets into a living space.  In a recent investigative report, journalists with the Texas Tribune and NBC News looked into the question of what portable-generator makers have done to prevent deaths caused by CO emissions from their products.  I summarize and comment on their findings in what follows.


For people like Craig Curley, the answer is "not enough."  Caught in another weather emergency—Hurricane Ida, that struck the Texas and Louisiana coasts last Aug. 29—Curley bought a portable generator and set it up at his ex-wife's house in case the power went out.  Unfortunately, the generator was close to the open back door, and when he visited the house next day, he found that his ex-wife and their two children were dead from CO poisoning.


For manufacturers, the answer seems to be, "hey, we're trying."  The Portable Generator Manufacturer's Association (PGMA), an Ohio-based industry group, says through its representative Edward Krenik that about 60% of new generators have CO sensors that shut the generator down when the CO level becomes too high.  This leads to the further question of what too high is.


CO is a colorless, odorless gas that in high enough concentrations can kill a person in minutes.  A CO levels chart from a gas-sensor manufacturer says that the maximum safe indoor CO level averaged over 8 hours is 9 PPM (parts per million).  200 PPM will cause noticeable physical symptoms and will kill you in hours, and 800 PPM will kill you in a few minutes.  The ANSI-PGMA G300 specifications dated 2018 and housed at the PGMA's own website says that CO monitors for their generators must stop the machine within 10 minutes if it detects 400 PPM, and within 30 seconds if it detects 800 PPM.  That sounds adequate, but not great. 


From an engineering point of view, there is probably a tradeoff between making the CO sensor not sensitive enough, and killing people as usual, or making it too sensitive and having the generator cut itself off without a good reason to do so.  The levels chosen in the standard seem to be a reasonable compromise between the two extremes. 


There is another alternative, which was explored by a research team at the University of Alabama. They outfitted a portable generator with fuel injection and other measures that reduced the CO emissions by 90%.  Despite industry criticism that such measures would cost too much, at least one manufacturer has adopted them and sells a generator that emits much less than the typical levels of CO.


Why hasn't the government required all portable generators sold in the U. S. to be either virtually CO-free or to have CO safety interlock devices, or both?  It has to do with a kink in the Consumer Product Safety Commission laws that allow manufacturers to try developing their own standards first.  And that's what they've done, but for some people like Craig Corley, it's too little and too late.


The field of engineering ethics has seen this type of process work out in other fields before.  A new product or system is introduced, whether it's portable generators cheap and reliable enough for residential use, or steam railways, or steamboats.  Fatal accidents occur that could have been forestalled if the operators took certain precautions (don't put the generator close to a window, don't ignore track safety rules, don't let your boiler water run too low). 


At that point, the designers of the system face a choice:  do we double down on telling people how to run things safely, or do we design safety into the device itself so that even idiots who never read instructions can't hurt themselves?  That's putting it a little harshly, but that's what the choice amounts to—jawboning or foolproofing. 


If persuasion and consumer education don't work, the deaths continue and eventually, some particularly gruesome tragedy pushes the regulators and politicians over the tipping point, and a new regulation is passed.  Voluntary industry standards have the flaw that there is always somebody out there wanting to sell things a little cheaper and a little more dangerous.  So if society wants to be sure that such evasions don't happen, third-party enforcement—typically by a government agency—is the only choice.


The PGMA is now facing that choice, and so far they are dragging their feet.  They point out that even if all new generators from this moment on were sold with both CO detectors and emission controls to reduce CO by 90%, there are a lot of old dangerous units out there which will be around for decades, considering that emergency generators spend most of their time not being used.  And nobody wants a witch hunt to ferret out old dangerous generators from private hands. 


While even one accidental death in this fashion is too many, you could make the economic argument that if CO regulations increase the price of portable generators so much that some people don't buy them, and an emergency comes along like the Big Texas Freeze, and those folks who otherwise would have bought a cheap generator die instead, well, CO prevention could actually lead to more deaths.  Not being an economist, I'm not going to make that argument, but I trot it out just to show that the problem is more than a simple one of greedy generator manufacturers heedlessly endangering the public.  


My guess is that sooner or later, all portable generators for consumer use will be required, by the government, to have CO shutoff sensors, and the higher-end models will make low CO emissions a bonus selling point.  It's impossible to make the units perfectly safe, and if users follow instructions, the units are no more dangerous than running your car in your driveway—depending on how old your car is.  I've heard that with catalytic converters and all, it's no longer possible to commit suicide by closing your garage and sitting in the car with the motor running.  But I'm not about to try it to find out.


Sources:  The article "Generators can cause deadly carbon monoxide poisoning.  But the industry resists rules to make them safer." by Lexi Churchill, Perla Trevizo, and Ren Larson of the Texas Tribune and Mike Hixenbaugh and Suzy Khimm of NBC News, appeared originally on the Texas Tribune website at, and was republished in the Jan. 2, 2022 Austin American-Statesman, where I saw it.  I also referred to the PGMA's website at, obtained the figure of CO deaths during the Big Freeze from, and referred to for the effects of CO poisoning.

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