Home » Occupational Respiratory Diseases: The Farmer, His Lungs, and Mold

Occupational Respiratory Diseases: The Farmer, His Lungs, and Mold

by Amanda Demsky
farmer on a tractor

Little-Known Agricultural Health Hazards

According to the Centers for Disease Control and Prevention (CDC), “agriculture ranks among the most hazardous industries. Farmers are at very high risk for fatal and nonfatal injuries; and farming is one of the few industries in which family members (who often share the work and live on the premises) are also at risk for fatal and nonfatal injuries.”

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The CDC estimates that over 167 agricultural workers suffer farm-related injuries every day (60,995 annually). The more common ages for fatal injuries range between 16 and 19 with 23% resulting from machinery malfunction or misuse, 19% involving motor vehicles, and 16% due to drowning. These leading sources constitute 58% of farm-related youth fatalities. The majority of nonfatal injuries among all age groups, however, are classified as either a sprain or strain.

In addition, the National Agricultural Safety Database (NASD) reports that “farmers account for more than 30% of adults disabled by respiratory illness.” Interestingly, the NASD also found that “a large percentage of farmers are nonsmokers.” This begs the question: In an industry known for its fresh-air work environment, what could possibly account for chronic respiratory conditions?

Respiratory Threats

Few realize that, while farming potentially provides a healthy and robust occupational habitat, it also accommodates a great number of respiratory hazards. Contemporary farming, especially, puts the farm worker at risk with various lethal airborne contaminants and toxins, such as hydrogen sulfide, pesticide vapors, field dust, and nitrogen dioxide.

Even fewer perceive the more common risk. Whether it’s modern or antiquated, genetically-modified or organic, all types of farming pose the same threat: mold.

Many farm processes encourage the development of mold and the transference of mold spores, as well as the release of mycotoxins and mycoestrogens. The more common inducer of mold growth on a farm is storage. Grain silos, for instance, present the perfect habitat for mold, as their structure promotes moisture and heat, while the grain within provides decaying, organic nutrients. All three supply the mold precisely what it needs to grow.

As the mold matures and the silos are uncapped or the crops are transferred, the farm worker is exposed to billions of airborne, microscopic mold particles that have attached themselves to the dust from the field or flecks from the stored grain. According to the NASD, it is estimated that a farmer inhales up to 750,000 of these mold spores per minute. That’s 360,000,000 within an 8-hour shift. With numbers like that, it’s no wonder that a good portion of those spores will make it past the body’s natural, defensive filters (e.g. nose, hair, mucous) and gather in the lower lungs, where the majority of gas exchange takes place. The toxins from the mold spores are then carried with the oxygen through the bloodstream and distributed throughout the body. Eventually, the body’s only defense is to exhibit an allergenic type of pneumonia.

Farm-Derived Respiratory Illnesses

There are many types of farm-derived chronic respiratory illnesses (some of which are caused by synthetic chemicals), but there are two that are specific to mold exposure: Organic Dust Toxicity Syndrome (ODTS) and Farmer’s Lung.

ODTS goes by many names, such as Grain Fever, Toxic Alveolitis, and Pulmonary Mycotoxicosis, but it is more commonly referred to as Silo Unloaders Syndrome since exposure most often occurs when a silo of mold-infested grain is unloaded or when the silo is merely uncapped, which permits the spores to be carried on the air currents. Since mold spores teem in the billions and attach themselves to any type of microscopic particle, a farmer is at risk for developing ODTS anywhere there is an excessive amount of dust, especially around silos, grain storage, and hog and poultry barns.

Farmer’s Lung, otherwise known as Farmer’s Hypersensitivity Pneumonitis (FHP), is a noninfectious allergic disease caused by repetitive contact with mold spores. Frequent subjection forces the body into a defensive, overly-sensitive state, often mimicking the sudden onset of flu symptoms or even pneumonia. Over time, this affects normal lung function by disrupting the exchange between oxygen and carbon dioxide in the blood. Recurring exposure to mold causes significant impairment and even scarring in the lung tissue, which results in permanent damage. The NASD reports that “many farmers are forced to leave the occupation due to the physical limitations caused by farmer’s lung.”

Despite dissimilar titles, both ODTS and Farmer’s Lung share the same causation and symptoms.

At-Risk Farm Activities

The NASD claims that the following activities put the farmer most at risk for developing these respiratory illnesses and should not be done without proper safety equipment:

  • working in dusty fields or buildings
  • handling hay
  • working in silos
  • feeding or working with feedstuffs
  • working in corn silage
  • uncapping silos
  • cleaning silos or grain bins
  • working around animal feathers, hair, fur, or droppings
  • working around fish meal
  • applying fertilizer

Late winter and early Spring increase the chances of acquiring ODTS and Farmer’s Lung because the colder, wetter seasons allow for more indoor laboring with both hay and grains, which are generally baled or transferred for animal feed. The stored crops have had ample time to develop mold since harvest and the confined space of a barn, for example, promotes a greater concentration of mold spores.

Precautionary and Preventative Measures

According to the NASD, if mold is already present, the farmer has a few options:

  • wet down feed before transferring it to minimize dust
  • convert to mechanical or automated feeding or feed-handling systems
  • wet down the top of the silo before uncapping ensiled material
  • use some wetting techniques when cleaning out grain bins or other dusty areas
  • use respiratory protection when handling mold or dusty materials

In spite of the suggestions made by the NASD directly above, MoldBlogger.com does not condone any use of moldy feed, whether for human or animal consumption. Ingesting the types of mold that infest, for example, cereal crops – maize (corn), barley, oats, wheat, rice, and sorghum – threatens the overall health of the consumer. Food allergies can develop, as well as recurring yeast infections (candida). An imbalance within the gut can occur and gastrointestinal/bowel diseases can stem from that. The mycoestrogens of some molds can cause a hormonal imbalance in both male and female, disrupting natural development of the reproductive organs, as well as cause infertility and create a vulnerability to specific cancers and diseases.

It is beneficial to both the farmer and the consumer (whether human or animal), to safely dispose of all feed materials that show signs of mold. If anything, the NASD’s above suggestions should be adhered to for the proper disposal of moldy materials.

The best methods against mold are preventative. Here are the more acceptable suggestions made by the NASD:

  • identify contaminants in the work environment
  • minimize the amount and type of contaminants in the work environment
  • avoid exposure to contaminants and mold spores and dust from decayed grains and forages
  • limit exposure to all contaminants
  • operate within a controlled environment whenever possible (e.g., cab, control room, etc.)
  • use mechanical controls to remove air contaminants (e.g., fans, exhaust blowers, filters etc.)
  • bale hale, ensile crops, and harvest an store grain at recommended moisture [levels]
  • dry grain properly before storage
  • [adequately] ventilate crops to keep them cool
  • maximize ventilation in dusty areas
  • move work outside whenever possible
  • avoid dusty work in confined areas
  • wear protective equipment (including respirators)

To reduce the risk of exposure, the National Institute for Occupational Safety and Health (NIOSH) encourages farmers and farmhands to invest in respirators and use them during the above scenarios. The NIOSH-approved disposable particulate respirator (N-95 or N-100), if properly fitted, will protect the farmer not only from fungi and dust, but also from bacteria, insects, and toxic fumes from animal waste. (Many farmers and farmhands use disposable dust masks. These are not designed to block microscopic particles – mold spores – or fumes.)

Post Mold Exposure

If exposure is suspected, the farmer can verify his suspicions with the following symptoms within the first 3 to 8 hours:

  • shortness of breath
  • tightness in chest
  • fatigue
  • dry, unproductive cough
  • muscle ache
  • headache
  • chills
  • fever
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The two most overlooked symptoms are a dual feeling of drowsiness and depression. More severe reactions exhibit a longer effect, which has been likened to the flu, pneumonia, or a nagging chest cold, and has been known to last anywhere from 12 hours to 2 weeks.

First-time and mild exposures generally don’t pose a lasting effect. However, it is still possible to acquire persistent Farmer’s Lung from a single exposure, depending on the health of the farmer and the type and amount of mold spores. Repetitive exposures, however, cause chronic symptoms and acute disease within the lungs. If additional exposure is not avoided, a farmer’s condition could worsen to the point of death.

Never self-diagnose. Respiratory issues should not be ignored, no matter how moderate or tolerable. Only a medical evaluation can determine the severity of each case. A victim should consult a doctor if conditions persist or worsen within 48 hours.

If the doctor suspects a farm-related respiratory condition, he or she may order the following procedures:

  • blood tests
  • chest x-rays
  • breathing capacity test
  • inhalation challenge
  • lung tissue examination
  • immunological investigation
  • lung function test

Warning: Many health professionals are not aware of – or trained to diagnose – Farmer’s Lung. Symptoms may be mistaken for the flu, asthma, pneumonia, or even the common cold. It is imperative that a farmer or farm worker make clear his or her case to the doctor and insist that there has been exposure to mold and that the issue could be Farmer’s Lung or Organic Dust Toxicity Syndrome. A misdiagnosis could eventually cost a farmer his life.

A farmer’s greatest personal strength – as both a preventative measure and a post-exposure treatment – is to feed the body what it needs to adequately resist the infiltration and damage caused by mold. The body was designed to heal itself if supplied proper nutrition, exercise, fresh (non-contaminated) air, sunlight, and adequate rest. In addition, when faced with yeast or mold infections, victims should adhere to a strict anti-fungal diet and avoid all circumstances and activities that would put them at risk for more exposure.

For more information regarding mold, mold prevention, and mold solutions, please check out the rest of MoldBlogger.com.


National Institute for Occupational Safety and Health. Agricultural Safety. Centers for Disease Control and Prevention website. https://www.cdc.gov/niosh/topics/aginjury/. Published June 19, 2014. Updated December 15, 2014. Accessed February 1, 2017.

Glen H. Hetzel, et al. Farmer’s Lung: Causes and Symptoms  of Mold and Dust Induced  Respiratory Illness. National Agriculture Safety Database website. http://nasdonline.org/1853/d001796/farmer-039-s-lung-causes-and-symptoms-of.html. Published 2005. Accessed February 1, 2017.

Dennis J. Murphy. Agricultural Safety and Health: Farm Respiratory Hazards. PennState Extension website. http://extension.psu.edu/business/ag-safety/health/e26. Published 2017. Accessed February 1, 2017

About the Author: Amanda Demsky is the mother and personal chef of two boys, the domestic technician of a three-bedroom desert home, and occasionally, a freelance writer and editor. Feel free to follow her on Twitter @fullquiver777

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Gran Ola February 2, 2017 - 12:18 am

Them poor farmers!

San Tan Restoration Professionals February 4, 2017 - 10:39 am

Thank you for sharing


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