Can A Furnace Cause Allergies? 3 Ways It Can and How You Can Fix It


Allergies are always annoying and inconvenient, regardless of what form they may come. They make even simple everyday tasks difficult to accomplish. But what is more troubling is the thought that the very thing you depend on warmth and comfort may trigger or exacerbate your family’s allergies. Can a furnace cause allergies?

Your furnace cannot be the source of your allergies if it is properly and regularly maintained. A well-maintained central heating system can even help prevent the spread of allergens in your breathing space. On the other hand, a poorly maintained furnace can host various harmful particles in its dirty filters or air ducts that can trigger or aggravate existing allergies.

can a furnace cause allergies

Before we dive into the deep-seated link between allergies and the state of your furnace, let’s look into this very common yet extremely irritating natural bodily reaction: Allergies.

A Rundown on Allergies

The American Academy of Allergy Asthma & Immunology (AAAI) describes an allergy as a chronic condition that can make you miserable in its mildest form but can put your life in danger in severe cases.

It all starts with our immune system, hardwired to protect our body from harmful intruders. Its troops of antibodies are always ready, day and night, to fight these toxins and expel them from our system.

This defense system works beautifully as a machine, except when it is the case of an allergic reaction. Some seemingly harmless things like dust, pollen, and pet dander can be mistaken by our immune system as dangerous invaders and attack them. Mold spores, dust mites, and different kinds of insects and their droppings are indeed disgusting but they can definitely cause an alarm to a hyperactive immune system.

These “invaders” when inhaled are now targeted as allergens. Our antibodies rushed in to eradicate these particles but they release histamine in the process. Histamine is a chemical compound that produces allergy symptoms such as sneezing, coughing, itchy red and watery eyes, sinus congestion, or runny nose.

The situation can turn from bad to worse when mild allergic reactions become severe allergies. Allergy sufferers can experience anaphylaxis or the critical and fatal kind of allergy. This may manifest in difficulty in breathing because of the inflammation of the nasal passages, throat, and tongue, low blood pressure levels, skin rash or hives, vomiting, and diarrhea. Continued exposure to allergens without immediately administering proper allergy medication can be deadly.

Now that we have a clearer understanding of allergies, let’s shift our focus on how regular maintenance, or lack thereof, can either help prevent an allergy attack or make allergies worse.

How Can a Well-Maintained Furnace Help Prevent Allergies?

Seasonal allergies are a kind of sensitivity to allergens that only happen at specific times of the year. For example, pollen or the minuscule grains of seeds produced by flowers, trees, and other varieties of plants is the number one irritant that sets off summer and spring allergies. Meanwhile, the culprits for most winter allergies are dust, dust mites, and mold particles.

How does your heating system protect you from these common allergens? There are at least three ways:

  • It minimizes your exposure to allergens from outside. Noone objects to letting fresh air come into your home now and then. Sadly, your desired “fresh air” is mixed with a cocktail of allergen particles so you shut your windows and doors against your will. But this is where your furnace or air conditioner comes to your rescue. These machines thrive in an airtight environment to keep the processed air contained indoors. Like pulling two weeds in one yank, your furnace keeps you away from inhaling pollen and other harmful irritants and keeps you warm and cozy indoors.
  •  Its furnace filters trap harmful pollutants. Truth be told, the main function of filters is to block the entry of solid particles that can damage the internal components of your heating system. But the happy consequence of that is it removes potential allergy triggers from getting processed and being released back to your living spaces as your furnace distributes heated air. In fact, one of the better upgrades when buying a furnace is the air cleaner.
  • It improves indoor air quality by controlling humidity. If your furnace is in excellent condition, it can significantly improve the quality of your air inside the home as it manages moisture levels indoors. The relative humidity, which makes you feel icky and muggy, is lessened as the air gets warmer. Mold, as one common allergen, have less of a chance to flourish in areas with low humidity.

How Can an Unmaintained Furnace Cause Allergies?

It is super easy to just ignore your furnace once the warmer months arrive, cover it up, and hide it away. But when the cold air returns, many homeowners simply do not bother to check the state of their heating system before turning it on. The result is incessant sneezing, coughing, and wheezing which they usually blame on the change of weather.

This vicious cycle continues for years until the heating system never gets thoroughly cleaned and maintained which poses a great risk to your family’s health.

How exactly does a neglected furnace prompt your allergies?

  • Clogged furnace filters and air ducts recirculate indoor allergens. In the summer, dust, pollen, pet hairs, and other irritants can build in the filters and heating ducts. Once the winter months hit and we turn on our heaters, all those allergens get dispersed throughout our homes.
  • Uncontrolled humidity levels promote mold growth. Slowly but surely the absence of regular and quality furnace maintenance will decrease the efficiency of your furnace to adequately warm your home. Some sections of the house may have high humidity while other areas are too dry. These are perfect breeding grounds for mold spore particles to grow, thus exposing your family to year-round allergens.
  • Poor indoor air quality weakens the immune system. A faulty furnace cannot be expected to maintain good indoor air quality. Research shows that exposure to indoor air pollution can impact our immune system negatively. Children are more susceptible to developing asthma and lower lung capacity if placed in a setting with too many air toxins.


Allergies are never fun. But many people learned to live with them by avoiding allergy triggers as much as they can. If you or any of your family members are vulnerable to indoor allergies we discussed above, make it your goal to subject your furnace to proper maintenance at least once a year by a qualified professional.

Whether your furnace is old or a newer high end variable speed furnace, the advice is the same.

A well-kept furnace can be your friend that keeps allergies at bay or an enemy that triggers allergy attacks.

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