Christmas tree mould and asthma – how to avoid your decorations triggering allergies, breathing problems

There can be endless debate about the best time to set up a Christmas tree, but the symbols of holiday cheer can pose an often-unheeded danger to people with asthma or allergies.

That is because of something called “Christmas tree syndrome”, a term United States allergy specialist Dr Lawrence Kurlandsky introduced with two studies suggesting that live Christmas trees can be covered in mould that can cause breathing issues. People with asthma or allergies are particularly susceptible, because 70 per cent of the moulds found in live trees can trigger severe asthma attacks, fatigue and sinus congestion.

Dr Sharmilee Nyenhuis, another specialist at the University of Illinois at Chicago, says some people who have mould allergies do not realise the dangers of Christmas tree mould.

“Around five to seven days would probably be a good amount of time to have a live Christmas tree up, since after seven days the mould count starts to increase exponentially,” she says.

The warmth inside homes is one reason the mould on trees gets more dangerous with time, says Melanie Carver, vice-president of community health and marketing for the Asthma and Allergy Foundation of America.

“The trees themselves most likely have mould spores and pollen on them that are brought into the home,” Carver says. “Mould grows in warm, humid environments, and sometimes the inside of your home provides the perfect conditions to encourage mould growth.”

Kurlandsky published his studies in 2007 and 2011 and has since retired. If a Christmas tree has mould when it’s brought into a home, it makes sense that people living there may notice symptoms from being exposed to it, such as sinus and nasal congestion, stuffiness, a runny nose, itchy, watery eyes or a cough, Nyenhuis says after reviewing Kurlandsky’s research. If the mould affects someone’s asthma, it could lead to shortness of breath or chest tightness, she says.

“If those symptoms are always happening around the holiday time, every December or end of November when people are putting up holiday decorations, you may want to consider that maybe you’re someone with allergies and speak with your doctor,” she says.

JT Maier, owner of mould remediation business AdvantaClean in the US state of Illinois, says artificial trees can be just as problematic because they might be covered in dust or mould if they haven’t been properly stored.

“An artificial tree has its advantages and its risks,” he says. A big mistake is to put it into storage without any bag or container. Sitting there for 11 months, the tree is bound to collect dust; add in humidity and that creates the problem.

“Water mixed with dust equals mould growth,” Maier says.

For those with allergies who still want a holiday tree, there are quick ways to protect against mould’s danger. Maier recommends storing any holiday decorations, including artificial trees and ornaments, in a climate-controlled space, and not to use cardboard. Pests love it and it also will get mouldy if it gets wet.

Washing a real tree before bringing it in the home to remove pollen or mould is a good idea, but can be tricky in crowded Hong Kong. If you can, wash it with a small amount of bleach in water, Carver suggests. Bringing a tree inside before it’s completely dry also can promote mould growth.

Nyenhuis says it’s not necessary to use caustic cleaning products – they can also be dangerous for those with breathing issues.

“If you have a live tree, I’d recommend doing a vinegar solution, one part vinegar to one part water, and washing the tree with that,” she says. “Vinegar has mould-killing properties and it’s a very cheap, low-cost intervention.”

Artificial trees can also be washed, or taken outside for a good shaking to release any dust, Carver says.

Trees aren’t the only festive decorations that can raise concerns during the holidays for people with asthma. Artificial snow or flocking on trees can release tiny particles into the air, which can irritate the airway. Scented candles, cleaning products, indoor fires and cold air are all asthma triggers, Nyenhuis says.

Both she and Maier say those with breathing issues, holiday-related or otherwise, might consider an air purifier or air cleaner system to help improve the air quality in their homes.

“Everyone’s asthma is different and people may have different allergies,” Nyenhuis says. “But poor air quality impacts all people with asthma.”