'Luminous multi-coloured mould'​? Yellow mould? Toxic black mould? Why understanding mould species is the key to more than just lurid headlines

When a West Midlands newspaper recently ran a story about a vulnerable couple whose lives have been blighted by ‘multi-coloured, luminous’ mould growing in their council flat, they shone an important light on an all-too common problem in social housing in the UK.

But their coverage of this case also revealed one of the many prevalent misunderstandings surrounding mould in the UK media. 

Although luminous, multi-coloured mould sounds alarming, the colour of mould in itself is no indication of the harm it can cause. All mould is potentially harmful to human health, and as the WHO states, nobody should live with it, whatever the colour, whatever the species. 

If all mould is potentially harmful, this does not though mean that identifying species of mould is not important. It is just that identifying mould species requires a more sophisticated approach than just identifying its colour.

This is where the power of qPCR testing comes in. PCR testing was widely acknowledged as the gold standard for Covid-19 testing, because it is so accurate, so rapid, and so reliable. Using the PCR method to analyse household dust for traces of mould DNA rapidly and accurately identifies how much of which species of mould is present in a property. 

While many kinds of mould test can identify the presence of mould in a building, only DNA testing can reliably show whether that mould is growing inside or whether it has blown into the building from the outdoor air. 

DNA species analysis can also give an indication of what materials the mould might be growing on. And because different mould species thrive at differing levels of humidity, DNA species analysis can reveal hidden damp problems in a property. Finally, DNA species analysis can also help to identify the presence of mould species that are known to produce mycotoxins – toxic substances that are strongly suspected to cause health problems. 

So, identifying mould species matters, because it helps specialists find hidden mould and it helps them to focus on the mould that matters the most. But it can’t compete with the yellow, multi-coloured or toxic black categories that only exist in the media’s imagination.