Humidity limitation (% between limit lines)
The standard’s wording, as the sources below reproduce it:
“Indicates the range of humidity to which the medical device can be safely exposed.”
ISO 15223-1:2021, 5.3.8 · ISO 7000-2620
What it means for you
The two figures are the lowest and highest relative humidity the maker says the device can take — in storage, transport or use, as the instructions specify. Example: 15 % and 93 % means keep it out of places wetter than 93 % relative humidity.
Whether a device is right for you is a question for your pharmacist, nurse or doctor.
- What it looks like
- A circle holding a % sign over water waves, with a short angled limit line at the top right and another at the bottom left, each with a percentage printed beside it (for example 10 % and 90 %).
- Where you see it
- Electronic devices (meters, monitors, hearing aids) and IVD kits, on the box or in the instructions.
- Other names
- humidity range; relative humidity limits
What it does not tell you
It does not say whether the range applies to storage or to use — the instructions do — and it says nothing about liquid water.
Often confused with
Indicates the range of atmospheric pressure to which the medical device can be safely exposed.
More symbols in “Limit lines”
Sources
ISO 15223-1 is a paid standard, so the wording above is quoted as 3 publishers’ public documents reproduce it. Each was fetched and read on the date shown:
- Boston Scientific: Symbols Glossary — ISO 15223-1 5.3.8 “Humidity limitation — Indicates the range of humidity to which the medical device can be safely exposed.” Image labelled ISO 7000-2620. Checked 2026-09-25.
- NE Scientific: Master Symbol Glossary (CTF-100011 Rev 01) — Shows the circle with % and waves between two angled limit lines for reference no. 5.3.8 (ISO 7000-2620). Checked 2026-09-25.
- Stago: Glossary of symbols (520233-A_EN) — “Humidity limitation — Indicates the range of humidity to which the medical device can be safely exposed. NF EN ISO 15223-1, symbol #5.3.8.” Checked 2026-09-25.
Plain-language parts are in our own words; quotations are the sources’ wording.