Health effects of inadequate indoor air quality are often poorly understood due to the large number of potential indoor air contaminants and parameters, the possibility of interactions between contaminants and on individual responses to them. For example, there is no direct correlation between airborne mould and health effects according to the World Health Organisation ( WHO). There are defined levels which can be used to provide guidance as to whether the airborne mould levels are excessive or should be controlled.An indoor air quality assessment includes the measurement of temperature, relative humidity, carbon dioxide, carbon monoxide, and air flow. Where the testing for other gases, dusts or specific substances (e.g. formaldehyde, volatile organic compounds, and mould) is required, specialised air sampling equipment is used. At times, it may be necessary to forward air or mould samples to accredited laboratories for analysis to assist in the determination of recommended controls.
The control strategies almost always involving better ventilation; reduction of water egress into buildings; reduction of moisture content to be 40% of building materials such as wood and plaster; better cleaning of mould affected areas and application of mould resistant paint in some circumstances.