At what concentration can hydrogen sulfide be detected by the human nose?

Hydrogen sulfide has a distinctive rotten egg odor, which makes it detectable at very low concentrations. The human nose can generally sense hydrogen sulfide at concentrations around 0.0005 to 0.3 parts per million (ppm), but the lowest threshold commonly cited for reliable detection is approximately 1 ppm.

At 1000 ppm, the concentration is significantly higher than the olfactory detection threshold, allowing most individuals to easily perceive the gas. Additionally, while higher concentrations can lead to olfactory fatigue—where the sense of smell diminishes due to prolonged exposure—the ability to detect the odor at 1000 ppm is well established in industrial hygiene references.

The other concentrations listed exceed this detection threshold significantly, making them less relevant in the context of the initial detection capability of the human nose.