Christmas tree growers say a family doctor's claim about Christmas trees triggering allergies is "unfair."

Dr. Peter Lin, who is based in Toronto, says Christmas trees may be partly to blame for winter allergies, asthma and sinus infections.

As soon as a tree is cut down, it's dead and allergy-causing mould sets in, he said.

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Dr. Peter Lin says to shake off any dead needles before bringing the tree indoors. (CBC)

"You bring it back into your home and now you've got some nice warm temperatures, it starts to dry out and the mould becomes air-borne and then people can have allergies to that."

Studies have shown the normal mould count inside a typical household is about 500 to 700 mould spores per cubic metre of air, said Lin.

But after having a Christmas tree up for two weeks, the mould count jumps ten fold to about 5,000 spores, he said.

Tree farmers aren't happy about what they see as an attack on the annual tradition.

"Christmas tree growers are like any other farmer - they take as many steps as possible to prevent any moulds, parasites, or contamination," said Shirley Brennan, executive director of the Christmas Tree Farmers of Ontario, which represents 125 growers across the province.

"There is potentially mould anywhere. This is unfair to tree farmers," she said.

The group offers tips on its website about how to best care for Christmas trees to keep them fresh.

Suggestions include storing them outside in a cool, dry place until you're ready to decorate, making a fresh cut across the trunk once it's inside the house, keeping it away from heat sources and using a tree stand that can hold plenty of water. Trees may drink up to four litres of water per day, according to the website.

Artificial trees also problematic

Lin admits even artificial trees can cause allergic reactions.

They might be fine for the first year, but after being stored, they can cause problems.

"The artificial tree, we put in the basement where it's damp, and then guess what, you get mould going on that as well. And, you can also have dust."

For people who can't imagine celebrating Christmas without a Christmas tree, Lin suggests getting a real tree as soon as possible after it's been cut.

"Then what you do is bang it on the ground and that gets rid of all the dead needles and gets rid of the mould that might be growing on them as well."

Transporting trees on the roof of a vehicle can also help blow some of the mould spores off, said Lin.

The tree can also be hosed down, but must be left outside to dry before being moved indoors, he said. Otherwise, it will encourage mould growth.

Once the tree is moved indoors, it shouldn't be kept up for longer than three or four days and the water source should be kept covered because it could also become a breeding ground for mould.

Lin also recommends taking care with ornaments, particularly ones with fabric, which can get dusty and mouldy.

They should be vacuumed and wiped down before being placed on the tree and stored in plastic, he said.

Other holiday favourites that can cause allergic reactions include potpourri and scented candles, said Lin.

Poinsettias can also be a trigger for people who are allergic to latex gloves because they contain a similar chemical, he said. They're fine to have in the house, but should not be touched.

Chimneys should be cleaned and ready for festive fires and people with food allergies, such as peanuts, should be on the lookout any transfer or traces, he said.

Lin also recommends that anyone taking allergy medications that can cause drowsiness to be mindful of the potential risks of mixing them with too much holiday cheer, such as rum and eggnog.