One person in every seven could be allergic to traditional Christmas trees, say doctors.

A fir tree festooned with lights and decorations is one of the archetypal Christmas images. But the Annual Meeting of the American College of Allergy, Asthma & Immunology, Dallas, will be told that they harbour a hidden danger.

Manufacturers of artificial trees will be delighted by the news that a study suggests that the evergreen spores from Christmas conifers could be responsible for a season surge in wheezing, runny eyes, rashes and headaches in allergy sufferers.