H2S makes gas "sour", right? And "sour" wells are common in the salt domes structures along the Texas/Louisiana coast. Also in the California oil fields, around Bakersfield and even inside L.A. (Signal Hill).
There's even a town in Texas named Sour Lake -- so called because H2S bubbles up thru the lake and the whole area smells like rotten eggs.
It's a poison, to be sure. But, if the concentration is high enough to smell, it's still far from deadly. If it's high enough to knock you out, that's another matter.
Yeppers. It’s been a while since I lived/worked down there, but I believe that if the concentration of H2S gets to 4 PPM or higher, it’s called a sour well.
And like you wrote, just cuz you can smell it does not mean you are dead. It’s not like phosgene. (if you smell cherry blossoms, you’re dead) I remember being issued respirators at some of the chemical plants along the Gulf, along with the admonition that if the alarm goes off, do not inhale, and get your mask on within 10 seconds. Yikers.
I recall hearing in a high school chemistry class that as H2S gets stronger, people lose their ability to smell it. So someone exposed to an increasing concentration will often be unaware that they are about to be knocked out.