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Free carbon dioxide: Main Effects & Top 5

Published May 5, 2026·1min read

Hot springs with ≥ 1,000 mg/kg of free CO₂ are classified as "CO₂ springs." CO₂ bubbles cling to the skin, are absorbed transdermally, and dilate peripheral blood vessels.

National maximum
1600.0 mg/kg
@
Saga Yamato Onsen Amandi
Table of Contents
  1. What is Free carbon dioxide?
  2. Main Effects
  3. Free carbon dioxide Top 5 Hot Springs

What is Free carbon dioxide?

Hot springs with ≥ 1,000 mg/kg of free CO₂ are classified as "CO₂ springs." CO₂ bubbles cling to the skin, are absorbed transdermally, and dilate peripheral blood vessels.

Main Effects

  • Promotes circulation and peripheral vasodilation
  • Indicated for poor circulation
  • Warms the body even at lukewarm temperatures

Free carbon dioxide Top 5 Hot Springs

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

* Top 5 among onsen analysis records registered in this app

References

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