Asthma is thought to have many potential triggers

New research has shown that damp and mould-infested homes may be the cause of permanent asthma in children,

Poor housing is already linked to the illness but there is divided opinionas to whether they are an actual cause of asthma, or just a trigger attacks.

A report by Finnish researchers published in the European Respiratory Journal says they have proved this after surveying the homes of more than 300 children.

Asthma is now the most common chronic disease of school-age children, and rates have risen steadily in recent years in industrialised countries.

Results from a team led by Dr Juha Pekkanen, from the National Public Health Institute in Kuopio, suggests that as many as one in five cases of child asthma may be caused by moisture and mould in the home, with the severity of asthma increased alongside the severity of the damp in living areas.

The research compared the homes of 121 asthmatic children to those of 241 non-asthmatic children, with detailed interview and allergy tests to rule out specific asthma triggers in the environment, experienced civil engineers ranked all the houses in terms of the level of damp and presence of mould.

Everything from leaks, condensation and damp stains to peeling on the surface of walls was recorded.

Evidence of serious damp or visible mould was seen two to three times more often in homes inhabited by asthmatic children. Mould and damp in 'non-family' parts of the house, however, was not linked to the illness.

The researchers found evidence that mould and damp caused asthma in children, as opposed to worsening or triggering attacks in children whose asthma had another underlying cause.

Dr Pekkanen called for doctors to be aware of the link when treating child asthmatics.

However, not all experts are convinced that the evidence points to a cause for asthma, UK asthma experts are still not convinced mould can cause asthma.

A spokesperson for Cardiff University whose work on mould and asthma is funded by the charity Asthma UK, said the study suggests that Finnish children with newly-diagnosed asthma are more likely than other children to have moisture damage and mould in their homes. Adding it is not possible to distinguish conclusively between the role of moisture damage and mould as a trigger factors and any causal link with childhood asthma based on the current evidence.