"The data for steady-state-off measurements were long-tail skewed, with the top 5 stoves (9% of sampled units) emitting half (49%) of all steady-state-off emissions."

So, they have a couple leaky stoves in the equation and they extrapolate the data. But they never bother to determine what was leaking, which is actually a fairly simple thing to do since there are commercial leak detectors that are quite sensitive (https://www.southerncrossinc.com/wp-content/uploads/2019/10/...) to at home units that detect NG/propane/etc.

Plus there were quite a number of other WTF moments in the document that don't match with my understanding of current install practices around NG heaters/etc.

Not the least of which, is that if 1% of the usage (which is a lot!) is leaking that will easily show up on peoples meters and be something that can be smelled. Which granted most people don't run outside and check their meter in the morning after having turned off all their gas consumers but people do smell gas. I've known at least one person who ended up ripping up a bunch of the piping in their attic because it was leaking, but i'm guessing its more likely someone forgot about an old appliance with an actual pilot light or the data was categorized improperly.

Lets just say, that if you were honestly trying to run this study, don't you think you would want to go investigate some of the outliers to at least note that the top couple cases were broken valves, or rusted piping, or just debris in the gas line damaging/keeping the valve from closing (which is why modern gas codes require sediment traps) fully?

It's interesting to find out what the sensor may be actually measuring, and that it might actually be something, but I'm still left with the questions:

Is that stuff actually harmful?

If so, what could you even do about shower mist (at scale, as a reasonable thing to make a policy applying to all 7bn of us)?

And doesn't it still sound like the gas stove does not stand out as some special problem?

Or at least that, no article based on this source of data can be said to justify that conclusion.

Maybe the stove is doing something so much worse than farts and showers that it's worth giving up the utility and efficiency*, but this source of data does not show it.

* Efficiency including other gas appliances, ie, a gas clothes dryer is more efficient and interestingly, less fire risk than electric, but mostly the utility. Nothing else comes close to cooking with gas, it is simply by far the best tool for the job, and that is not an insignificant dismissable item.

> gas clothes dryer is more efficient and interestingly, less fire risk than electric

A regular electric dryer is 100% energy efficient, just like an electric resistance space heater. A heat-pump electric dryer can be 2-300% "efficient" (really COP) because it uses a heat pump.

A gas dryer is strictly less than 100% efficient - because like with any combustion device, some portion of the fuel is unburned and is sent out the exhaust/flue. Even the most expensive gas condensing modulating furnaces are only in the 90-97% combustion efficiency range.

Gas dryers are usually more time efficient though. They achieve such high temperatures (thanks to combustion) that they dry clothes 50% faster. And because gas is cheaper than electricity, they are cheaper to operate. The operational energy cost advantage vanishes when compared to heat pump electric dryers, however.

Electric dryers aren't 100% efficient if the source is the usual gas/coal/nuke/etc steam plant because the plant itself is only ballpark 50% efficient at converting the heat->electricity, then you take a percent or ten in transmission losses/etc. So, if the choice is pump the gas to a combined cycle gas plant, burn it, transmit the electricity to a resistivity heating dryer vs pump the gas directly to the dryer and burn it, the gas dryer will generally win.

Using a heat pump returns much of what is lost, but on balance in most places its sorta a wash. To be specific you have to look at the whole picture including the energy source, which requires actually picking a location/city and a particular product. And even saying maybe 100% of your power comes from PV+Wind (yah righ, haha) if you really want to lower the footprint the best plan is just to hang your cloths outside.

Then compare the parts & materials list of a gas dryer and a heat pump dryer.

You keep moving goal posts, but ok.

Yes heat pumps are more complicated. Likewise LEDs are more complicated than incandescent bulbs. Condensing furnaces are more complex than gravity furnaces. And nothing is simpler than a clothesline.

Higher efficiency usually involves higher complexity (EVs being an exception, although batteries themselves are pretty complex at tiny scales).

What's also great about heat pump and other condensing type dryers is that they are ventless. With a regular vented dryer, each time you run it you exhaust several thousand cubic feet of indoor conditioned air, which gets replaced by outdoor unconditioned (hot, cold, or dirty) air due to the depressurization of your house.

One way or another, you pay for reconditioning that air.

Depending on how much you do laundry, your local climate, and the price of energy, a ventless dryer (which can only be electric, naturally) can save you a lot in energy costs by avoiding that air exchange.