Can Inhaling Mulch Dust Make You Sick?

Mulching is an age-old horticultural practice that farmers, gardeners, and plant keepers use to improve soil quality, conserve soil moisture, and control weed overgrowth. It’s also an excellent way to enhance your garden’s aesthetics while boosting overall plant health—whether you’re keeping hardy succulents or delicate flowers. However, mulch is typically composed of organic matter, and it’s normal to wonder if inhaling the dust poses some health risks.

Inhaling mulch dust can make you sick, and the sicknesses are typically caused by dust particles, fungal spores, or bacteria in the mulch. These illnesses are also usually long or short-term respiratory conditions and affect humans and animals.

In this article, I’ll explore a few of the most common sicknesses mulch inhalation may cause in humans and focus on their most recognizable symptoms. I’ll also dive into the best ways to prevent them and how to treat anyone exposed to mulch dust. Let’s get started!

What Illnesses Does Inhaling Mulch Dust Cause?

Respiratory conditions are a big deal; unfortunately, an immensely beneficial practice like mulching can seriously affect lungs and respiratory tissue. However, the conditions caused by mulch dust inhalation may vary in intensity—usually depending on existing health conditions and the severity of exposure to the mulch dust. Still, you need to learn what these illnesses are and know what their symptoms look like, especially if you work with mulch often.

Here are a few sicknesses that inhaling mulch dust could cause:

  • Organic dust toxic syndrome
  • Legionellosis
  • Hypersensitivity pneumonitis
  • Histoplasmosis
  • Aspergillosis

Now, let’s explore each of these illnesses and conditions in more detail.

Organic Dust Toxic Syndrome

Organic Dust Toxic Syndrome (ODTS), sometimes called Farmer’s Fever or Farmer’s Lung, is a respiratory illness caused by inhaling organic dust—particularly from mold-containing matter like compost, mulch, and wood chips. However, it can also be triggered by aerosols, cotton, and grain.

Regardless of its cause, Organic Dust Toxic Syndrome causes flu-like symptoms in its victims and is especially common in farmers and gardeners that work with a lot of compost, manure, or mulch. Victims of ODTS usually develop symptoms 4 to 12 hours after exposure to contaminated organic matter, but it’s not uncommon to notice symptoms almost immediately.

However, Farmer’s Fever is a mild illness, and its symptoms typically disappear in two to three days, even without treatment. Still, you must visit a doctor if you have flu-like symptoms after handling mulch.

And while a single bout of Organic Dust Toxic Syndrome doesn’t cause much damage, recurrent health-related issues may weaken your respiratory health—resulting in more severe illnesses and conditions.

Fortunately, you can prevent ODTS by using a mask or wetting dusty areas of your garden before mulching.

I recommend using the 3M Half Facepiece Reusable Respirator (available on to protect yourself from mulch dust. It’s an excellent, comfortable, and reusable respirator that’s perfect for small-scale gardeners and big-time farmers.


Legionellosis is a general name for any of the respiratory illnesses caused by Legionella bacteria. These bacteria include Legionella longbeachae—which can be found in organic matter like mulch and garden soil—and Legionella pneumophila, which thrives in water systems.

The condition caused by Legionella longbeachae results in acute pneumonia or pneumonia-like symptoms and usually leads to death if left untreated. And while it affects the lungs, Legionellosis is not contagious. Still, it’s a pretty severe sickness.

The symptoms usually start with headaches and flu-like symptoms two to ten days after exposure to contaminated mulch dust. However, most patients will develop blood-streaked coughs, nausea, and shortness of breath on the second day. These latter-stage symptoms also include chest pain, confusion, and severe diarrhea.

You should visit the doctor if you develop any of these symptoms after handling mulch, but I recommend you use a respirator or face mask to prevent the illness in the first place. And since the bacteria that causes Legionellosis can also stick to the skin, I advise you also use gloves when mulching.

Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis is pretty similar to Organic Dust Toxic Syndrome (ODTS) in many ways. It’s caused by the dust particles in mulch—as well as molds, bacteria, and some chemicals—and affects the lungs by causing inflammation

The condition is caused by the body’s immune system’s attempts to remove inhaled particles and is an allergic reaction to these particles. The inflammation isn’t serious, but the symptoms of hypersensitivity pneumonitis vary from individual to individual.

Some patients may experience coughing, fever, chills, and other flu-like symptoms, while others may only notice dry throat and mouth. However, these symptoms usually develop immediately after exposure and may last for a few hours or several days.

Still, hypersensitivity pneumonitis can also be subacute—just like Organic Dust Toxic Syndrome (ODTS)—resulting in more severe symptoms with prolonged exposure to the mulch dust particles. These symptoms usually clear up after a few months but might lead to mild lung trauma.

However, there’s also a chronic form of hypersensitivity pneumonitis. This form of sickness is a lifelong condition caused by prolonged contact with mulch dust over a long period. It can result in constant symptoms and permanent lung trauma in affected patients.

As always, you should see a doctor for treatment if you suspect you might have hypersensitivity pneumonitis, especially if you work with mulch. However, you can also wear respirators and face masks to protect yourself from the mulch dust.


Mulch inhalation can also lead to histoplasmosis, a lung infection caused by Histoplasma capsulatum—a fungus that lives in moist organic matter like soil, mulch, and compost. Inhaling mulch contaminated with the spores of this fungus can lead to this infection. The illness is similar to Organic Dust Toxic Syndrome (ODTS) but can also affect the eyes and skin.

However, there have been a few cases where histoplasmosis also affected the adrenal glands.

Patients suffering from histoplasmosis will notice symptoms like fever, chest pains, and headaches. However, they may also notice dry cough and muscle pains—mostly flu-like symptoms.

These symptoms typically appear 3 to 10 days after exposure, and the condition may be life-threatening in rare cases.

Severe histoplasmosis presents tuberculosis-like symptoms in its victims, and these victims usually have existing health conditions before infection. Still, people with weakened or compromised immune systems are the most vulnerable to histoplasmosis.

I recommend seeing a doctor if you notice the symptoms I described in this article. You can also protect yourself from Histoplasma capsulatum spores by storing your mulch correctly and using protective equipment like masks and respirators when mulching.

Fortunately, Histoplasma capsulatum only thrives in select areas of the United States, like Mississippi. Therefore, there’s very little chance your mulch might be infected with fungal spores. However, it’s better to be as safe as possible.


Aspergillosis is another respiratory sickness that you could get from inhaling mulch dust. And like histoplasmosis, the illness is caused by fungal spores. This fungus is usually Aspergillus fumigatus, but exposure to other Aspergillus molds can also cause Aspergillosis.

The Aspergillus fumigatus fungus shares many features with Histoplasma capsulatum and can grow indoors and outdoors. Therefore, you might be at risk of infection whether you keep indoor plants or grow an outdoor garden.

The fungus can grow in mulch and soil as well as on plants, food, and everyday surfaces. Therefore, it’s more common than histoplasmosis-causing Histoplasma capsulatum.

However, Aspergillosis only affects a small group of people, especially individuals with existing health complications, compromised immune systems, and chronic respiratory problems. It’s pretty rare to develop the sickness if you’re healthy, but it’s best to be as safe as possible when dealing with fungal spores.

There are three main types of Aspergillosis:

  • Pulmonary Aspergillosis
  • Invasive Aspergillosis
  • Allergic Bronchopulmonary Aspergillosis

Pulmonary Aspergillosis usually affects immuno-compromised patients as well as individuals with respiratory trauma and results in symptoms like fever, wheezing, and bloody coughs. However, these symptoms usually manifest in the latter stages of infection.

The symptoms of invasive Aspergillosis are similar to that of pulmonary Aspergillosis, but patients may also experience kidney failure, shock, and liver complications. Invasive Aspergillosis is a serious health condition and may result in death if left untreated. However, it only occurs when the infection enters the bloodstream from the lungs.

Allergic Bronchopulmonary Aspergillosis is sometimes referred to as ABPA and is an allergic reaction to Aspergillus fumigatus spores. It’s common in patients with a history of allergies and asthma but produces symptoms similar to these conditions. Some patients might also notice extreme fatigue, especially during strenuous physical activities. 

I recently wrote an article that’s pretty similar to this one, and I explored if the smell of mulch could make you sick. You can check it out to learn essential facts about the smell of mulch and how it could affect your health: Can The Smell Of Mulch Make You Sick?


Mulch dust inhalation can make you sick, depending on what’s in the mulch and how it’s stored. These illnesses can be mild or severe, but you should always visit the doctor if you notice any of the symptoms I’ve described in this article.

I also recommend using protective equipment like masks and gloves when working with mulch to be safe. However, the chances of suffering from one of these symptoms are pretty low, so you should be fine.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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