Expert comment: Poor ventilation to blame for black mould

Dr Simon Clarke, Associate Professor in Cellular Microbiology, University of Reading said: "Mould inside people’s homes is nothing new, but its persistence is commonly associated with poor living conditions. It is usually associated with a damp environment and condensation. But even brand-new homes can suffer while plasterwork dries out.  

"Moisture can result from lack of heating, but also because of poor ventilation.  It’s perfectly possible for houses to be both warm and damp if there’s insufficient air circulation. As people struggle with high fuel bills, they may be tempted to try to eliminate all possible sources of heat loss, but this could cause other problems.

"Indoor mould is cause by growth of fungus and it can be difficult to eliminate.  They can be irritants and cause allergic reactions when inhaled. Some of these fungi also produce toxic substances. The elderly and very young are at increased risk of respiratory problems from indoor mould, as are some people with respiratory problems, such as asthma. And the weakened immune systems of chemotherapy patients place them in particular danger."