Air

What humidity is healthy at home?

Short answer

Aim for relative humidity between 40 and 60 %. If it stays higher for long, the risk of mould increases.

Explanation

Warm air can hold more water than cold air. Moisture condenses on cold walls or windows, and that is where mould grows. WHO estimates that 10 to 50 % of indoor environments in rich countries have damp problems. Cooking, showering, drying and breathing add moisture every day.

Rules of thumb

• Target: 40–60 % relative humidity. [SW-S20]
• Do not dry laundry indoors without extra ventilation or a vented dryer. [SW-S20]
• Keep cooler rooms separated from warmer ones with a closed door, so moisture does not move to cold walls. [SW-S20]

Pitfalls

• A dehumidifier does not fix a leak or thermal bridge; find the cause. [SW-S29]

Search terms

These search terms are in Dutch; only terms that also find a topic in English are links.

luchtvochtigheid hygrometer condens schimmel

Read also

• How do I prevent and fix mould?
• How do I air my home without losing much heat?

Sources

1. SW-S20 Wie lüfte ich richtig? Tipps und Tricks zur Schimmelvermeidung — Umweltbundesamt (DE) (Reference date 2026-09-27)
2. SW-S29 WHO Guidelines for Indoor Air Quality: Dampness and Mould — Executive summary — WHO via NCBI Bookshelf (Reference date 2026-09-27)

Reference date: 2026-09-27 · Translated with AI from the Dutch original.