This term is often used to describe the situation where there is mould on clothes and shoes in cupboards, on the bottom of furniture, and a pervasive, or even intermittent, musty smell. This is often due to the trapped air in a damp or poorly ventilated subfloor space (the space between the ground the underside of the floorboards) permeating to internal rooms.
Air quality Issues in
Australian Homes and Workspaces
Improving indoor air quality via reducing dust and pollen counts and reducing indoor relative humidity levels are proven to reduce asthma triggers. Improving (increasing) ambient temperature in cold spaces has also been shown to improve conditions for asthma sufferers. (Note that professional medical advice should always be sought in relation to asthmatic or allergic conditions)
A mouldy home is a damp home. Mould needs moisture to grow. The causes of internal dampness in homes can be micro climate driven – particularly if the home is well shaded; exposed to damp humid sea breezes; experiences above average rainfall; is built on sloping land such that there is perennial subterrannean water flows.
Musty odours are almost certainly a sign of mould. The mould grows in the damp surfaces but then emits microscopic spores that are carried in the air. That musty smell is sometimes referred to as "mould fart". Mould does not have to be visible to be present indoors. We like to say "listen to your nose" when asked about how to identify internal mould.
Fine particulate matter generally refers to particles measuring less than 2.5 microns (PM2.5). Outdoor sources of PM2.5 include combustion engines (in all types of vehicles), coal dust, bush fires and land clearing. Inside, PM2.5 can be generated from mould, cooking and fireplaces.
Window condensation is the most obvious example of a damp home. Australian homes typically experience condensation from April to October. At night, in autumn and winter, glass panels are colder than the air, so the moisture in the air condenses to form "crying windows".
This issue was really brought to the fore in the summer of 2019/2020. Many Australians experienced indoor and outdoor air quality at levels never seen in their lifetimes. The climate scientists suggest this could become the "new-normal" for Australians.
Many councils recommend installing double glazing and other acoustic insulation for homes affected by traffic, airport or transport noise. Often governments fund ventilation solutions in conjunction with installation of double glazing.
If, compared to other places you have lived, you find your house unusually cold, it could be due to the home's orientation to winter's warming sun – but usually this is a sign of a damp home. In a damp home, the energy from the sun, and/or from heating appliances is first used to dry the home, and then to heat the home. Often occupants will be so focused on keeping warm they will be unaware for the air quality impacts in such premises.