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Free hydrogen sulfide: Main Effects & Top 5

Published May 5, 2026·1min read

Free hydrogen sulfide (H₂S) is the source of the rotten-egg aroma unique to sulfur springs. Absorbed via both skin and inhalation, it strongly dilates peripheral blood vessels.

Free hydrogen sulfide: Main Effects & Top 5
Max in this app
16.9 mg/kg
@
Noboribetsu Onsen
Table of Contents
  1. What is Free hydrogen sulfide?
  2. Main Effects
  3. Free hydrogen sulfide Top 5 Hot Springs

What is Free hydrogen sulfide?

Free hydrogen sulfide (H₂S) is the source of the rotten-egg aroma unique to sulfur springs. Absorbed via both skin and inhalation, it strongly dilates peripheral blood vessels.

Main Effects

  • Peripheral vasodilation via skin and inhalationFree hydrogen sulfide is absorbed through both the skin and the respiratory system. This action directly dilates capillaries and other small blood vessels, which can powerfully boost peripheral blood circulation.
  • The signature rotten-egg aroma of sulfur springsThis distinct, pungent odor is the defining characteristic of hydrogen sulfide gas. The smell, often compared to rotten eggs, serves as a non-visual cue that you are bathing in a potent, therapeutic sulfur spring.
  • Caution required in poorly ventilated bathsIn high concentrations, hydrogen sulfide gas can be toxic. For this reason, proper ventilation in and around the bathing area is legally required to ensure bather safety and prevent the risk of poisoning.

Free hydrogen sulfide Top 5 Hot Springs

Top 5 hot springs registered on this site with the highest content.

RANKING BY THIS MINERAL CONTENT

Top 5 by Content

27 matches

* Top 5 by mineral content matching the filters among onsen analysis records registered in this app

References

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