This study will, for the first time, compare the health (with an emphasis on, but not exclusively, asthma and nose and chest problems) of occupants of leaky homes, to the health of occupants of dry non leaky homes. These days, it is possible to identify many microbes (bacteria and moulds) in house dust by measuring the traces of the chemicals that they produce. Some of these may be particularly irritant to the nose and lungs and be responsible for some of the symptoms that occupants often report. We will also look at specific moulds and grow them in the laboratory. Some of these moulds may enter homes already impregnated on new gib board that come to life if the gib gets wet from a leak. We will look at NZ gib board to see if this is a problem in NZ.