Fresh Christmas trees may be responsible for epidemic peaks of respiratory illness that occur in the weeks around the Christmas holiday, U.S. researchers say. Lead researcher Dr. Lawrence Kurlandsky, formerly of Upstate Medical University in Syracuse, N.Y., and colleagues provided clippings from their own trees. The study, published in the journal Annals of Allergy, Asthma and Immunology, found the samples contain a variety of molds, most of which are identified are potential allergens shown to increase the risk of wheeze, persistent cough and allergic sensitization in infants. However, Kurlandsky suggested that the allergens may not affect all families. \"If you and your children don\'t have any obvious allergies, then it is probably not going to bother you,\" Kurlandsky said in a statement. For those who are susceptible to allergens, Kurlandsky suggested checking with the nursery where you purchase your tree to see if it offers tree washing services. If the nursery is not able to clean the tree, use a garden hose to spray off the tree and allow it to dry before bringing it into the house. Kurlandsky also suggests minimizing the length of exposure to the three -- evidence suggests the longer a tree is in the house, and the warmer the environment, the more spores are released into the air. The study says a household air purifier in the same room as a tree can help remove allergens from the air. Artificial trees, if not stored properly, can introduce mold and dust into the home, aggravating allergies, Kurlandsky said.