Christmas trees trigger asthma

A major decision in many households before Christmas is whether to buy a real or an artificial tree. However, research has shown that either may pose an increased risk to asthmatics and other allergy sufferers.

One study, by the American College of Allergy, Asthma, and Immunology, examined the relationship between mould growth on live Christmas trees and indoor air quality, following a consistent increase in asthma and sinus complaints among patients in winter, especially pronounced during the holiday season.

Mould allergy affects up to 15 per cent of the population, and people with sensitivity to certain varieties may experience nasal, eye and throat irritation, nasal stuffiness and headache.

There is also a well-documented link between asthma attacks and moulds, and the added risk of invasive fungal disease among people with compromised immune systems.

Researchers measured mould counts in a room containing a live Christmas tree, beginning when the tree was brought inside and decorated. Normal indoor air has a mould level of 500–700 spores/cm³, and for the first three days counts remained at 800 spores/cm³, then began escalating rapidly, reaching a level of 5,000 spores/cm³ by day 14, when the tree was removed.

Such high levels have been associated with allergic rhinitis and an increased rate of asthma symptoms, as well as asthma-related hospital admissions. The study recommended that families with allergies in general, and mould allergies in particular, should not keep a live Christmas tree for more than a few days at most, and remove it as soon as they detect signs of increased allergy symptoms.

But mould and dust, including dust mites, can also accumulate on artificial trees, ornaments and other decorations when they are stored from one Christmas to the next. The process of unpacking the boxes can stir up the allergens.

It is recommended that both real and artificial trees be taken outside and shaken before decorating, and that decorations, if they have not been stored in airtight plastic bags, be wiped down to eliminate dust and mould.

Other possible holiday risk factors for asthmatics include strong scents from potpourri and scented candles, smoke from an open fireplace, as well as holiday stress.