Mould and your health
In a water-damaged building it is rarely the amount of visible mould that decides who becomes unwell. It is how the people inside respond to it, and what the mould produces. Here is the plain-English background.
Why exposure matters more than visible growth
We assess the indoor environment and the exposure of its occupants, not mould alone.
Around a quarter of the population carry a genetic predisposition that leaves them unable to clear the mould and other microbial biotoxins in their environment, so the same water-damaged room can be harmless to one person and disabling to the next.
Mycotoxins and biotoxins
Mycotoxins are secondary metabolites produced by moulds and fungi while they are actively growing, normally present in small quantities as a defence for the organism. Grouped with bacterial toxins, they are collectively called biotoxins.
In high amounts, as can occur in water-damaged buildings, they become potentially harmful to human health. Over 700 individual biotoxins are now identifiable from environmental samples taken in homes, workplaces and schools.
How they reach the body
Biotoxins are very resilient and can last for years. They are carried on very fine particulates from the breakdown of the mycelial mat.
These particulates can be nanoparticulate, small enough to bypass the cilia and deposit deep in the alveoli of the lungs, where they cross into the bloodstream and travel to major organs. There they can lead to exacerbation of the innate immune system, which may lead to the multi-symptom, multi-system illness known as Chronic Inflammatory Response Syndrome (CIRS).
Hidden mould and MVOCs
Fungi and bacteria produce Microbial Volatile Organic Compounds (MVOCs) as a byproduct of their metabolism, and many cause the characteristic musty odour of mouldy environments.
Because MVOCs permeate walls and partitions, unlike mould spores, they can indicate hidden mould growth behind surfaces without destructive testing.