My sister is making a presentation to her local commissioners regarding regulation of local wells that emit a particular poison gas.
I would like some simpler, more relatable examples for her to use to compare the poison she’s talking about.
What I mean:
Can you think of some well-known, common substances that are completely harmless at 10 PPB but are extremely deadly at 100,000 PPB? Liquid is ok, but airborne is better.
And the numbers don’t have to be exactly that, just similar- exactly is great, though.
(I say slam BP because they are involved)
Most things are harmless at ppb level - you need to look at things like very specific neurotoxins to find things that are dangerous to people at that sort of exposure.
Even the exceedingly toxic Nickel tetracrabonyl is only immediately fatal at about 30 to 40ppm, and that is not something I would ever flippantly expose myself to.
What toxic gas are we talking about here? HCN?
I think Dan is right - you’re working backwards from your conclusions. It reminds me a little of that mock safety website that warns about the dangers of being exposed to large quantities of dihydrogen monoxide since it can be fatal if ingested in large volumes.
Well, 100,000 ppb is 100 ppm, so things like Nickel tetracarbonyl are fatal at that level, but at 10ppb, I don’t think even that would be fatal - I don’t think it would kill you, since the median lethal dose for a 30 minute exposure is about 3ppm, still way, way above 10ppb.
Hydrogen cyanide is nasty shit that I don’t like being around, and its median lethal dose is about 300 ppm for a 10 minute exposure. I think 10ppb exposure wouldn’t even be noticeable to a human.
What specific gas are we talking about that is coming out of these wells?
My point is that I can give you a list of many things that would be very, very toxic to me at 100ppm that would be just fine at 10ppb - the comparison is just not all that useful.
I assumed it was H2S, since that is a common component of natural gas and oil wells. Even so, it is only similarly toxic to HCN - 300-400ppm is a fatal exposure over about 10 minutes. It’s not going to be fatal at 10ppb, although you could probably smell it.
Most things you’re looking for that are fatal at 100ppm are going to be rated “4” in the blue part of the safety diamond. HCN, H2S, Ni(CO)4. Things like chlorine gas are slightly above that (although you’re unlikely to run across much elemental chlorine since it is so reactive), as is carbon monoxide gas on its own.
Some people can detect the odor of this gas at 0.00047 ppm (0.47 ppb)
No acute effects at .01 ppm (10 ppb) Some studies have looked into respiratory health of chronic, long term low level exposure at 2 ppm (2,000 ppb)
At 1- 10 ppm (10,000 ppb), it can lead to irritation of the eyes, nose and throat.
At 10- 50 ppm (10,000 - 50,000 ppb) it can lead to dizziness, nausea and vomiting.
So… It looks like Hydrogen Sulfide actually meets the criterion for your answer. At 10ppb, some people may be able to smell it, but there are no acute affects whatsoever at this level. There may be some chronic affects at levels 20 times this high (2,000 ppb). At 100,000 ppb, this gas is deadly.
As others have said above, there are many, many substances that would also meet the toxicity criterion that you’ve set.
Toxicology is highly specialized and requires someone with a PhD in it to interpret for most people. There is a guy named Steve Packham in Utah who is very damn good at it. You can find him on the internet. I hired him once and he explained things accurately and so that a lay person could understand them. He ain’t cheap.