Dehumidifiers control humidity levels in the home, workplace and other indoor areas such as swimming pools, garages and boats. A dehumidifier is usually used for comfort or health reasons, as well as protecting cars, caravans and other equipment from mould, rust and deterioration due to excess humidity.

Humidity is simply the amount of water vapour that is present in the air. The recommended humidity level for dwellings is 45-55 per cent.

Humidity above 60 per cent causes condensation and encourages the growth of mould, fungus, mildew. It also enables bacteria, viruses and dust mites to breed quickly which causes health problems such as allergies, arthritis and asthma.

If the percentage of water vapour in the air is too low it causes excess drying which can trigger skin irritations such as a dry nose, eczema and chapped skin. It can also damage possessions, such as wooden furniture, by drying it out too much.

High humidity indoors is caused by a number of natural factors, in particular the weather. However modern insulation, double glazing, central heating, dishwashers, washing machines and bathrooms can increase humidity, when humidity caused by washing up and cooking for example is trapped indoors.