If you feel short of breath, cough, or suffer from conjunctivitis while you are at home, it may be due to your Christmas tree. Due to the heat of the interior, tiny fungi grow on the tree and spread in all of the rooms because of spores, vegetative multiplication cells.Spores are responsible for the ‘Christmas tree’ syndrome. The latter is similar to a hay fever that occurs in winter. In 2011, Dr. Kurlandsky found that 53 types of fungi were growing on the 28 trees he was analysing. His work was transcribed in a study published in the American journal Annal of Allergy, Asthma and Immunology.In a study conducted in 2007, scientists analysed the air in a house for 14 days. The number of spores per cubic metre increased from 800 on the first day to 5000 on the fourteenth. If the fir tree stays indoors for a long time, the mould will spread much more quickly.Beware of asthmatics and people allergic to pollenDr. Nhân Pham-Thi recently told Le Figaro about the ‘Christmas tree’ syndrome: ‘You need to already be sensitive or have an allergic predisposition in order for any allergy attacks to occur because of the trees. Those who are likely to suffer from this syndrome are often allergic to pollen, such as that of cypress, for example’.People with a seasonal allergy are therefore more likely to be affected by the Christmas tree. Asthmatic children can also be affected by severe allergy attacks. ‘If the person knows they are allergic, they have to continue a long-term treatment,’ added the allergist, who advises not to keep the tree more than seven days at home.