Skip to next element

How a Good Ventilation System Can Reduce Allergies

Air ventilation systems provide and circulate fresh air within our homes. This can take many forms, from simply opening a window to the more intricate mechanical ventilation systems that provide airflow through air conditioning and heating.

allergies reduced with ventilation

How do ventilation systems work?

Every ventilation system relies on the same basic principle, regardless if the air is traveling through an open window or an air conditioner: air will always flow from areas with high pressure to areas with low pressure.

When the air pressure inside your house is higher than the outdoor pressure, air will find a way out. A lower air pressure inside your home does the opposite – fresh air from outside will flow in until the building and outdoors reach a pressure equilibrium.

Why is it important to have adequate ventilation?

Quality air ventilation is good for our health, lets us live comfortably within a building, and improves the structural integrity of our homes.

For example, enabling air to exit our kitchens as we cook allows us to live free from fears of carbon monoxide poisoning. Ventilation also ensures that our bathrooms don’t become too stuffy during a hot shower, and that doors open and close easily when entering or leaving the house.

So, not only does ventilation provide a building with fresh air, it circulates that fresh air throughout the home while getting rid of the indoor pollution. This dirty air can contain something as harmless as a bad smell, or a substance as dangerous as toxic chemicals released by microorganisms.

A home maximizes its fresh air when the ventilation system is working properly.

With homes becoming increasingly airtight, knowledge of how ventilation can affect our day-to-day lives is as important as ever. Today’s post will describe how good natural and mechanical ventilation systems can help reduce the negative effects of the most common allergens in our homes.

What causes allergies?

Allergies are a negative immune system response to an otherwise ‘good’ object. We’ve all felt these allergy symptoms, whether it’s sneezing caused by seasonal allergies, an itchy throat after visiting a friend with dogs, or a skin rash due to eating seafood.

There are many reasons that our bodies negatively react to otherwise ‘good’ things. Your allergies may be genetically inherited from one or both of your parents, or they may be due to the environment that you were raised in (it’s often a combination of both).

For example, if you’ve ever moved to a different part of the country, you may have noticed that you felt free from allergies. Only to realize, months or years later, that the new location’s oak pollen suddenly bothers you.

This is because your body had to ‘learn’ the allergens that the new area offered. When your immune system senses that something is invading, it produces antibodies to fight the invader off, even if the intruder is not actually dangerous. Over time, your body will respond more quickly to subsequent exposures to this new location’s oak pollen.

Producing antibodies to fight off invaders is normally a good thing, like in the case of viruses. But with allergens (those things that are not really attacking your body), this just leaves you feeling uncomfortable throughout a certain season.

The risks of allergens can be much more severe for certain people. Allergies can induce asthma attacks or even cause something as life-threatening as anaphylaxis.

Fortunately, certain treatments help reduce your allergic reactions, no matter how serious they might be. Today, we will focus on how home ventilation can reduce three common allergens: mold, dust mites, and pollen.

How does air quality affect allergies?

How can ventilation reduce allergies?


What is mold?

Mold is a type of fungus that is common in both nature and inside our homes. We all know how it’s dangerous to eat moldy food, but the mold growing in our bathrooms and basements may be much more risky and harder to detect.

Outside, in nature, mold functions as a decomposer of dead plant parts such as wood and leaves. While this is an important role in the forest, indoor molds can harm our health and the structural integrity of our homes.

Mold allergies are a health issue when the fungus can settle, grow, and reproduce in areas that we occupy.

Fungi produce spores as a means of reproduction and dispersal. It’s these spores that, once our body perceives them as a bad invader, cause most of the sneezing, coughing, and runny noses.

Molds also release ‘mycotoxin’ chemicals, which cause disease in humans.

One type of mold that you might be familiar with is ‘black mold’ (or Stachybotrys chartarum). Black mold can be especially threatening to our health because it produces an unusual amount of mycotoxins.

While not especially common out in nature, buildings often contain black mold because its environmental preferences are quite similar to ours. The fungus thrives in places with low sunlight, low competition with other microorganisms, high humidity, and lots of available cellulose (found in cotton, wood, and wallpaper).

How can ventilation reduce mold inside my home?

The bad news is that mold spores are ubiquitous. It’s impossible to completely get rid of all the spores floating in the air around us. However, it is feasible to prevent mold growth and control the amount of these spores that are present in our indoor environments.

One of the best ways to prevent indoor mold build-up and sporulation is with ventilation. Introducing a space with clean, dry, air while allowing humidity to escape, creates an environment that is unfavorable to most fungi.

For example, most of us intentionally introduce lots of heat and moisture into our bathrooms at least once a day – while we shower. Simply running the exhaust fan or opening a window (if it’s dry outside) can prevent the settlement of mold during a shower.

Basements are another optimal breeding ground for mold. Pipes, water appliances, and the lack of windows are just a huge invitation for mold to move on in; especially if ventilation is neglected.

Utilizing proper ventilation throughout the home can create a space that’s free from mold build-up, whether the mold is toxic or just a mild irritant.

Dust mites

What are dust mites?

House dust mites, or simply ‘dust mites,’ can refer to any mite species found in association with a residence. Dust mites are extremely difficult to see with the naked eye due to their small size and colorless body. However, despite being virtually invisible, dust mites are certainly noticeable to people who are allergic.

We’re not trying to gross anyone out, but these microscopic arthropods feed on human skin cells, pet dander, and mold – their scientific name is even Dermatophagoides, which means ‘skin eating.’

Dust mites often find shelter in bedding, carpets, and sofas, so they are most common in bedrooms and living spaces. Furthermore, dust mites thrive in a moist and dirty environment.

How can ventilation reduce dust mites inside my home?

Like with mold, ventilation can mitigate dust mites by controlling moisture levels. Many people will recommend vacuuming and washing sheets to get rid of these pests, but scientists have found that humidity reduction is the best technique for preventing dust mite allergies (Korsgaard 1982).

A humidity level of 85% is ideal for dust mites (Davies 1958) and the mites dry out below 60% humidity (Spieksma et al. 1971). For some perspective, the EPA recommends that homes are kept at humidity levels between 30 and 60% to maximize comfort while reducing susceptibility to mold and dust mites.

By providing quality ventilation to your bedrooms and living spaces, you’ll be ensuring that the space is suitable for you, but not the pesky dust mites.


What is pollination?

Pollen is something that we hear a lot about in the news, especially during spring and summertime. While most airborne allergens are common in certain buildings, plant pollen can affect entire cities all at once.

Lots of plants need pollen to make seeds and reproduce. Pollination is the movement of pollen from the ‘male’ part of the flower to the ‘female’ part of the flower. This process almost always happens with the help of animals (pollinators) like bees and beetles (Ollerton et al. 2011); but for some plants (especially grasses and trees), wind is required to spread pollen great distances.

Wind-pollinated plants generally produce much more pollen than insect-pollinated flowers because wind is such an imprecise method of transportation. While it’s important to have willows, wheat, and corn; pollen from each of these plants causes a different allergy. One that you’ve probably heard of before is ‘pollinosis,’ or ‘hay fever.’

How can ventilation reduce pollen inside my home?

This one might seem a bit counterintuitive at first because the natural approach is to close our houses off from the outside world to create a pollen-free refuge. Fortunately, ventilation is much more than just opening up a window; and mechanical ventilation allows us to live in our airtight homes while conditions outside are not favorable.

With mechanical ventilation, vents and fans pull outdoor air into the house through filters. As long as the filters are changed regularly (on about a monthly basis), airflow into and within the house should remain ideal and you’ll be able to continue to live with minimal allergen exposure year-round.

Another maintenance tip for keeping a pollen-free home is to make sure that your ductwork is in good shape. Any breaks to the ducts can make your system circulate pollutants throughout the home, rather than keeping them out.


Ventilation and allergies might have more in common than you originally thought. Quality home ventilation is vital to living in a clean and comfortable space. By reducing moisture levels and providing fresh air, ventilation can greatly prevent and reduce several of our most common and bothersome allergies.


Davies R. 1958. Moulds in dust and air. Thesis, University of London.

Korsgaard J. 1982. Preventative measures in house dust allergy. American Review of Respiratory Diseases 125: 80-84.

Ollerton J, Winfree R, Tarrant S. 2011. How many flowering plants are pollinated by animals? Oikos 120: 321-326.

Spieksma F, Zuidema P, Leupen M. 1971. High altitude and house-dust mites. British Medical Journal 1: 82-84.