Gardeners with health conditions have been warned to take precautions when tidying up their plots ahead of winter.

Doctors have warned that people with asthma or weak immune systems could be at risk from aspergillosis – a fungus found in compost heaps and rotting leaves.

Medics are advising gardeners with health issues to wear masks, to protect against microscopic dust that’s given off when rotting leaf and tree mulch is moved.

The campaign is being led by Gregor Campbell, 47, an art teacher from Scotland. He developed a chronic fungal infection after cutting up wet and rotting logs to store and dry out for winter.

Gregor said: “That summer I was being treated by doctors for a lung condition, but I had been cycling to work every day and was feeling well.

“One weekend I started getting night sweats and on the Monday I was in hospital. I was told I had pneumonia and was treated with antibiotics. I wasn’t getting better and lost a lot of weight.

“I only started getting better when the consultant diagnosed chronic pulmonary aspergillosis and prescribed drugs to fight the fungal infection.”

Gregor still only has two thirds of his breathing capacity after a fungal mass the size of a tennis ball was found in his lungs.

He added: “The suddenness of the whole thing shocked me.”

Professor David Denning of the National Aspergillosis Centre in Manchester, reassured gardeners by pointing out that most of us are immune to the fungus and have a healthy system that can fight it off.

He said invasive types of the infection affect 4,000 people per year, chronic types are suffered by 1,000 people and allergic types of the infection hit 3,500 people per year.

He added: “In asthma sufferers it can produce coughing and wheeziness.

“And in people with weak or damaged immune systems, such as cancer patients undergoing chemotherapy, the fungus can cause pulmonary aspergillosis – a condition which can cause irreparable and fatal damage to the lungs and sinuses.”