Yes, hydrogen sulfide is poisonous and can kill quickly. Many oil field workers keep H2S monitors on them to alert them to high levels of the gas, which has a strong smell similar to rotten eggs.

The "Hydrogen Sulfide Scavengers Market by Type (Water Soluble, Oil Soluble, Gas-Phase), Chemistry (Triazine, Nitrite, Iron Sponge), End-Use (Crude Oil, Natural Gas, Geothermal Energy, Industrial ...

The software update for the X-H2, X-H2S, and GFX 100S II is expected to come out in November. We'll be sure to let you know when it's officially released and ready to be installed on your camera.