Although there have been reports of respiratory symptoms in association with this enduring symbol of the holidays, the reaction may have less to do with the allergy than with other sources. Evergreen pollens, with their thick, waxy outer coating, have never been considered a significant allergen, and are unlikely to cause a reaction. According to one study, real and artificial Christmas trees can be a source of other allergens. Artificial trees are a potential source of mold and dust caused by improper storage. Real Christmas trees may act as a source for mold or contaminating pollens such as ragweed.
Interest also surrounds natural tree resins as possible airborne irritants.
In rare cases, the tree sap also may cause a contact allergic rash. The risks associated with a real or artificial tree can be reduced significantly by following simple precautions. Use a cloth to wipe clean your artificial tree. To remove pollens from your real tree, take it outside and spray it with a garden hose. Place the stump in a bucket of water and then allow the rest of the tree to dry thoroughly in the garage.