Condensation is water contained in the air, which converts (or condenses) from being a gas to a liquid when the air in the room comes into contact with a cold surface such as a wall or window glass. The amount of condensation that is generated depends on how moist the air is and how cold the surfaces in the room are.
Often, condensation is short-lived – such as that which occurs in bathrooms and kitchens because of the steamy atmosphere. Longer-term condensation can however arise in unheated rooms where air movement is restricted. These factors are largely controlled by the activities of the occupier and the way in which the house or flat is constructed. The effect of condensation may also be more pronounced in winter, because the building structure is cold and because windows are not opened as frequently to let the moist air out.
Since 2004, mould has been classed as a Category 1 risk to health as assessed under the Health and Safety Hazards Rating System (HHSRS) – the same class as asbestos. Landlords, councils and housing associations are legally bound to clear any outbreak under section 11 of the Landlord and Tenant Act, 1998.