Home dehumidifiers and health

by Deb
(Bensenville, Illinois)

Can over use of a home dehumidifier be bad for your body?


Hi Deb and thank you for your question.

Let me say at the outset that I am not a medical practitioner and I cannot offer medical advice. If you are experiencing a condition which you believe may be caused or affected by the level of relative humidity in your home or work place you should consult a physician. What I will attempt here is a summary of the main issues related to dehumidifiers which may, as I see it, have health implications.

Health and safety issues directly related to dehumidifiers.

Dehumidifiers are powered by electricity and, as with all electrical appliances, the manufacturer's safety instructions should be followed.

It is particularly important to comply with the instructions regarding the positioning of the dehumidifier and to clean the air filter at the recommended intervals. Both of these issues affect air flow and restricted airflow is one of the causes of dehumidifier fires.

The water collection container should be cleaned regularly to prevent mold formation. At the end of the dehumidifying "season" the container should be cleaned and thoroughly dried before being returned to the dehumidifier.

The water collected by the dehumidifier is not suitable for drinking due to the trace elements, mostly from metals, which are transferred to it from inside the unit. The water should not be used for watering vegetables or fruit bearing plants for the same reason. It may be used for watering other, non edible, plants.

Health issues arising from relative humidity levels.

My assumption is that this is what your question is about. Humidity at all levels can create or intensify minor and not so minor health problems. These problems are too numerous to detail here but the general rule is that to minimize the risk relative humidity should be maintained at a level between 40% and 60%. Depending on the susceptibilities of an individual this may require a dehumidifier when humidity is high, usually in summer, and a humidifier at other, mostly cooler times.

If you are allergic to mold spores a relative humidity level of 60% or less should prevent mold growth. If dust mites are your problem a level no higher than 50% is advisable. Please be aware that use of a humidifier to increase humidity in dry periods may also increase the dust mite population. Humidifiers may give rise to other health issues but as the site is about dehumidifiers I shall not deal with these.

Very low humidity levels have been held responsible for symptoms such as chapped skin and lips and a dry nose and throat but the evidence to support this is not conclusive. If you are in normal health you should suffer no discomfort at a relative humidity of 40-60%.

My general advice is that for most medically fit people extended use of a dehumidifier should not, of itself, give rise to medical problems and that the relative humidity level which causes the least problems for the majority of people is within the range of 40-60%.

For a more in-depth discussion of relative humidity and its influence on health problems you may like to read "Indirect Health Effects of Relative Humidity in Indoor Environments", a scientific paper by Anthony V. Arundel, Elia M. Sterling, Judith H. Biggin, and Theodor D. Sterling. You may download a copy of this paper here.

I hope this information is helpful.

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