For longer exposures to H2S, the recommended limits are a lot lower. For example, if you’re exposed for up to 24 hours, the ...

Hydrogen sulfide SMAC values will define safe limits for spaceflight crews on future missions and could drive new requirements for monitoring and mitigation of this chemical during spaceflight.

Since the end of November, the San Diego Air Pollution Control District has measured hydrogen sulfide levels above the California safety threshold in the Nestor area more than 15 times.