Resident's checklist: 5 things everyone should know about indoor air humidity

Indoor air shouldn't be too dry, but on the other hand, not too humid either. Here are five facts about the humidity in your rental home and tips on how you can influence it.

1. Humidity levels can vary between 20-70%

In winter, indoor air is drier and in summer more humid. In winter, normal relative humidity is 20-40%, and in summer, it's higher at 50-70%.

Air that's too dry can cause residents discomfort such as congestion and dry mucous membranes, but if the humidity is above 70% for an extended period, it can damage the home's structure. Moisture accumulating in structures can create ideal conditions for the growth of microbes like mould, which can be harmful to health.

2. The most important thing is to keep the air intake vents open

If air doesn't circulate in the home, excess moisture cannot escape.

All new SATO rental apartments have efficient mechanical ventilation. The performance of mechanical ventilation depends on the settings and power of the ventilation systems.

The natural ventilation in older buildings works well too, based on the temperature difference between indoor and outdoor air. Living rooms and bedrooms have air intake vents, and the kitchen and bathroom have exhaust vents.

Only maintenance personnel are allowed to adjust the exhaust vents, as the adjustment of one apartment affects all apartments connected to the same exhaust duct.

Whether it's a mechanical or natural ventilation system or a combination of both, it's important that residents do not cover or close the air intake vents.

Check out Jussi's tips for cleaning the vents ›

3. The kitchen hood is also part of the mechanical ventilation system

Indoor air humidity increases due to breathing and sweating, cooking, bathing, and laundry. If the home's air does not circulate, excess moisture cannot escape.

SATO regularly services ventilation systems to ensure they function properly. Residents are responsible for keeping air intake vents open and their filters clean.

In summer, natural ventilation requires that windows are occasionally opened, as outdoor and indoor temperatures are very similar, preventing natural draught.

In some newer buildings, the kitchen hood is part of the ventilation system. This type of hood should be kept at the lowest suction power when the apartment is unoccupied. Residents should check their resident manual to see the situation in their rental home and adjust the ventilation according to the instructions. The control panel for individual apartment ventilation may be located somewhere other than the kitchen hood.

If needed, you can also seek advice from our customer service.

4. Stagnant air is visible in the bathroom mirror

When air doesn't circulate in the apartment, it can often be sensed. When moisture remains stagnant, it means that air impurities such as street dust brought in by people and animals and carbon dioxide from breathing also stay in the apartment. Poor ventilation can cause fatigue, headaches, or other indoor air symptoms.

Visible evidence of stagnant air is moisture condensing on windows in cold weather, or a bathroom mirror that remains fogged for a long time after a shower.

5. The lid of a pot can help

You can influence moisture accumulation yourself. A simple trick in cooking is to use lids on boiling pots.

When showering, you can lower the water temperature or reduce the time spent showering. After showering, it's important to dry the floor with a squeegee and even the walls. Keep the bathroom door closed while showering, but if the bathroom ventilation feels inadequate, you can leave the door slightly ajar afterwards.

Whenever possible, dry your laundry in a drying room, outside, or on the balcony.

When to contact SATO?

If you have checked that the air intake vents are clean and functional, and the exhaust vents are working (a piece of paper sticks to the vent due to suction), but you still feel that your rental home's ventilation is not working, submit a fault report in OmaSATO or contact customer service.

SATO measures the indoor air of rental apartments

Since air quality affects living comfort, SATO has begun measuring the temperature and relative humidity of apartments. Almost all SATOhomes already have a sensor (information updated 7/23). Based on the measurement results, indoor air studies can be conducted, and indoor air problems can be detected and corrected. The results help adjust the ventilation system in the best possible way.

This article includes insights from SATO's Housing Health Manager, Aulikki Erälinna.