Do Christmas trees make you sneeze?

Although many people look forward to inhaling the fragrance of pine trees each Christmas, an equal number find the odors a source of torment--the cause of watering eyes, sneezing, headaches, congestion, even full-blown asthma attacks.

"As an allergist, it is not uncommon for me to see many patients who come in in December with allergy complaints related to evergreens," notes James Wells, professor of medicine, University of Oklahoma Health Sciences Center. "Most of the people who have such complaints are those who have asthma or those with an easily irritated airway or sinuses." Most Christmas trees have little pollen left by the time they are brought home. "There is, however, a fair amount of dust and mold on these trees, which can cause allergic or irritant reactions. Also, while some people like Christmas trees because of their sharp, pungent odor, other[s] have problems around them due to this strong odor, which can irritate the respiratory membranes, flare asthma, and contribute to sinus infection."

A third factor in...