Asthma sufferers who ensure their homes are free of mould see a big improvement in their symptoms, according to a new study.
Cardiff University's School of Medicine studied 182 people across South Wales who were living in mouldy conditions, and the results are published in the September edition of the medical journal Thorax.
Figures show the asthma problem in Wales is among the worst in the world, with 260,000 people receiving treatment, while hospital admissions for adults are 12% higher than anywhere else in the UK.
Dr Michael Burr, from Cardiff University's department of primary care and public health, said: "In the houses where mould was removed, the symptoms of asthma improved and the use of inhalers decreased more than in the other houses.
"Removing mould also led to improvements in other symptoms: sneezing, runny or blocked noses, and itchy-watery eyes.
"There was no clear effect on measurements of breathing, but this may have been because patients used their inhalers as needed so that they could always breathe freely."
An Asthma UK spokeswoman said: "The publication of this study adds to the increasing bank of research that indoor mould may have a link with asthma, however more work is needed in this area before definitive conclusions can be drawn.
"Research into this area does, however, highlight the importance of keeping your house dry and well ventilated."