Chemistry
Same chlorine family, different pH
A side-by-side look at the usual pH of household bleach and of HOCl-type solutions, and what that does to the HOCl / OCl⁻ split.
People often ask whether HOCl smells like bleach, or whether one irritates more than the other. The honest answer from the research behind this site is that the comparison has not been measured in the way it would need to be.
What a fair test would need
A useful study would put HOCl solution and bleach at the same available chlorine, under the same conditions, and measure odor or irritation for both. The source review behind this site looked for that and found no such study, for odor, skin or eyes.
What the nearby studies do cover
- Bleach cleaning releases HOCl gas. Stubbs 2023 measured air in a bathroom during cleaning with bleach and found more than 10 ppmv of gaseous HOCl near the source. So HOCl is part of what is in the air when bleach is used. The study had no arm using an HOCl solution, so it cannot rank the two.
- Bleach-only irritation and sensory work. Hostynek 1990 patch-tested alkaline sodium hypochlorite, and Kameda 2024 compared sodium hypochlorite with ethanol. Neither included HOCl. They describe bleach; they cannot support an HOCl comparison.
What we will not say
Until a matched study exists, this site does not claim that either one smells less, irritates less, or is more pleasant to use.
For the broader comparison, see HOCl vs bleach on disinfectant.org. For why the two are related at all, see Same chlorine family, different pH.
Sources: Stubbs 2023 (PMID 36602445); Hostynek 1990 (PMID 1965715); Kameda 2024 (PMID 38615666). Full entries on Sources.