‘Tis the Season – Are You Allergic to Christmas Trees? It May Actually Be Mold You’re Reacting to


Editor’s Note: This video is part of the ongoing allergy series in partnership with Columbia Allergy. To learn more about allergies, eczema, and related topics, please refer to our Allergy Guide!

It’s the holiday season… and Santa Claus is coming ’round… to your Christmas trees!

What are some of the allergy trends you are seeing in the Bay Area?

In general, the number of adults and children suffering from food and environmental allergies continues to rise. Changes in climate bring about changes in pollen levels for the common trees, weeds, and other seasonal allergens. Increases in sterility, especially during the pandemic can also potentially account for an increase in the number of allergic children. Common trees that cause allergic symptoms in the spring and early summer include juniper, cedar, cypress, acacia, birch, pine, mulberry, oak, walnut, olive, and privet.

Can you be so allergic to Christmas trees to the point where you cannot have them in the house?

Environmental allergies including those to trees can range from mild to severe, with severe allergy symptoms causing a significant disruption to a person’s quality of life. A person with a significant allergy to fir trees, mold, or dust mites may experience a flare in asthma symptoms, eczema, or allergic rhinitis symptoms when exposed to these allergens in a higher concentration within the home during Christmastime. A person suffering from a severe increase in symptoms that accompany having a Christmas tree in the home may choose to refrain from having a live Christmas tree to improve their quality of life.

Is everyone allergic to mold?

No, not everyone is allergic to mold. In order to be allergic to mold, your immune system must identify that specific mold as an allergen and build up a defense against the allergen through a process called sensitization. Once your body has been sensitized to the mold, then it can fight against it in the form of an IgE mediated reaction, causing symptoms like sneezing, itchy eyes, cough, congestion, and runny nose. Typically, sensitization to a specific type of mold only occurs after repeated exposure, which can take several years of seasonal exposure. You may be more susceptible to a mold allergy if a family member also has an allergy, or if you have other atopic conditions such as eczema, asthma, or other environmental allergies. Even those with mold allergies typically are only allergic to a few types of mold, and not all of them.

What is the type of mold that grows on Christmas trees / live trees?

The type of mold that is found on Christmas trees and live trees will depend upon the area in which you live. You can find the types of mold spores that are commonly found in your area by looking at pollen counts for your location as these typically also include the amount of mold found in the air and the type. You can find this on the American Academy of Allergy Asthma & Immunology website where they have certified pollen counting stations that are part of the National Allergy Bureau. It is common for trees to have mold spores, as these are a normal part of the natural outdoor environment. However, when these trees are brought into a warm and potentially more moist environment, this can create the perfect breeding ground for the mold spores to grow. To prevent this, keep your humidity levels between 40 and 50%. Anything above this can promote the growth of mold.
Mold counts for the Bay Area are low right now and consist of Ascospores that include Leptosphaeria, Venturia, Ascobolus, Diatrypaceae, Pleospora, Xylaria, Chaetomium, Sporomiella, Claviceps, Ascomycete, as well as Cladosporium and Cladosporium. Basidiospores are also present including Coprinus, Agrocybe, Agaricus, Inocybe, Laccaria, and Ganoderma. If your Christmas tree is coming from the Bay Area, it can have any of these mold spores on its surface and as a result, these may be the types of mold brought into your home.
You are invited to have a FREE discovery session at Columbia Allergy’s beautiful Redwood City clinic – all you have to do is call (650) 503-9770 and mention SFBAM!

How many types of molds are there? Are they all toxic to humans and pets?

There are thousands of types of mold out there, but not all are known to contribute to environmental allergies. The most common classes of mold that are known to cause allergy symptoms include Alternaria, Aspergillus, Cladosporium, and Penicillium. Many are not toxic to humans and pets but do have the potential to cause symptoms when these spores are inhaled by someone with an allergy to them. Stachybotrys chartarum, or black mold, has been thought to be toxic to humans. According to the CDC, there is no scientific test that has specifically shown a direct correlation between Stachybotrys chartarum exposure and specific health symptoms, but it is still best to remove any visible mold from your home.

Is there any way to prevent mold growth on indoor live trees?

Keeping indoor humidity levels between 40 and 50% can help to prevent the growth of mold. The use of a HEPA air purifier can also help to remove mold spores from the home and a humidifier can also help to regulate humidity levels to keep them within the desired levels.

How can I tell if I have a mold allergy? Can I get treated for it?

Seasonal symptoms when mold spores are in high counts may indicate a mold allergy. However, the best way to determine if you have an allergy to mold is through testing at your local allergist. Testing for mold allergies can include skin prick tests, IgE blood tests for types of molds, and intradermal testing. Once a mold allergy is detected, desensitization treatments may include allergy shots and sublingual immunotherapy (SLIT). Columbia Allergy also offers a unique allergy treatment called Precision Immune Targeting (ILIT).  Allergy shots, SLIT, and Precision Immune Targeting introduce a very small amount of the allergens into your body in the form of an extract. This small amount of the allergen in your body allows your immune system to get used to the substance so that you no longer develop symptoms. Precision Immune Targeting or Intralymphatic Immunotherapy (ILIT) is one of the most recent and exciting developments in allergy treatment.  This innovative procedure, involving monthly injections over three months, achieves the same results as those typically achieved through conventional allergy shots over 3-5 years. Like all types of immunotherapy, introducing the allergen allows your immune system to build tolerance so it eventually stops triggering allergic reactions.

Can hay fever turn into asthma?

Hay fever cannot turn into asthma as they are two different conditions with different pathophysiologies. However, atopic conditions such as asthma, eczema, and hay fever are commonly seen grouped together in a person and may have common triggers for exacerbations of the conditions. Atopy is the genetic tendency to develop allergic diseases due to a heightened immune response to common food and environmental allergens. The exact mechanism for how these conditions develop is unknown, but studies have shown that family members with these allergic diseases increase your personal risk of also having them, and having one of these conditions can also increase the personal risk of developing another atopic condition.

How dependable are IgE and skin prick tests?

Neither skin prick tests nor IgE tests are 100% accurate, so allergists often use results from both tests, coupled with a patient’s history and clinical symptoms to determine which substances are causing a true allergy. Skin prick tests are fairly accurate in determining true negative responses. This means that a negative result on a skin test has a very good chance of being a substance that the person is not allergic to. On the other hand, skin prediction tests are only about 50% accurate when it comes to positive results. That means that false-positive results can occur and do occur often. Food and environment-specific IgE tests have similar accuracy. Component testing, in which a patient’s blood is tested for sensitization to specific protein components in food, helps to improve accuracy in determining a true food allergy and the severity of the allergy. This is why it is important to compare skin prick results to IgE results and a patient’s history and exam.




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