Over the last half-century, buildings have become sealed, and this means that there is an over-reliance on mechanical air as compared to natural ventilation.
Owing to this, it is common to find mould in buildings even without the presence of water damage, as per the findings after the parliamentary inquiry into the causes of illnesses related to bio toxins in Australia.

Leading HVAC hygiene companies have advised that mould & its affects on health has turned into a serious issue that has to be addressed urgently. The company in its submission said that the swift increase of different synthetic products in all walks of life has created a mixed soup of biotoxins and volatile organic compounds. It has made ducted air conditioning repairs in Sydney a focal point in combating the menace.
The submission says that the spores of mould inside HVAC systems can be dispersed through air conditioning and ultimately degrade the quality of air indoors with contamination.

Chronic Inflammatory Response Syndrome (CIRS).
There is a lack of understanding about CIRS.
The submission further states that HVAC hygiene has reached a crisis point in Australia as there is no legislation currently to regulate the air quality indoors. This has facilitated the exposure to contamination by mould. The absence of legislation has permitted property managers and property owners to go for self-regulation as far as HVAC hygiene is concerned, resulting in the impact of poor IAQ in facilities and homes.
Most people ignore yardsticks like AIRAH’s Best Practices Guidelines as well as AS/NZ 3666 and 1668.
The submission further states that in the battle against CIRS in Australia, there is an urgent need for legislation to be drafted according to the guidelines of the industry as well as Australian Standards. This should be done as soon as feasible.
Post inquiry, several recommendations have been made to the Department of Health. These include the formulation of standards for testing and remediation of mould and additional research into the adequateness of present building codes to prevent mould in buildings. The need for CIRS education for health professionals and doctors is also stressed upon.
The Committee has suggested clinical guidelines for doctors and general practitioners for the diagnosis, treatment as well as management of symptoms of CIRS.
Plans are afoot to commission the National Health and Medical Research Council for researching CIRS as well as to establish links between bio toxins and mould.
Luck Wicks, a Federal Member for Robertson, said that the inquiry is a good opportunity to prove the link between mould and CIRS. It will lead to an improvement in building standards regarding moisture control. This requires the active participation of air conditioning specialists in Sydney. 
Wicks said that the report shed light on the outcomes of people who have mould related illnesses and are living in buildings with water damage.
She finishes by saying that with the adoption of these recommendations, there will be general knowledge about bio toxin-related illnesses, standards of practice regarding mould eradication will improve and lead to significantly better health outcomes, both for treatment and diagnosis of people who have CIRS.