Guard yourself against dusty and moldy grains

John Shutske
UW Madison
Grain dust is a complex soup of particles, with the smallest of them able to find their way deep into farmer's lungs.

Breathing grain dust can affect your comfort and is a health concern for all in the grain industry.

Grain dust is a complex soup of particles. The smallest dust particles are easily inhaled and find their way deep into the respiratory system. Grain dust is biologically active. It’s made up of plant material, mold, insect parts and excreta (bug poop), bacteria, endotoxins (toxins contained in the cell walls of some bacteria) and soil particles including silica.

Most people will have some reaction to dusty harvest conditions. Often, this will be a nuisance reaction (like a runny nose) or throat irritation. In some cases, bigger health problems occur. Endotoxins associated with some types of bacteria can cause problems for some individuals.

At low dust levels during prolonged and busy harvest operations, a cough is common. This might be an intermittent cough, producing more phlegm when you’re working near dust. Other symptoms are chest tightness/wheezing, sore/irritated throat, nasal and eye irritation and feeling stuffed-up and congested.

Bronchitis occurs as lung passages get inflamed. Grain dust can also be quite a debilitating concern for those with asthma.

A massive exposure to a thick cloud of dust is something to avoid. Massive exposures to moldy, dusty grain even for a short period of time can result in two distinct medical conditions having symptoms that include cough, chest tightness, malaise (a general feeling of discomfort, illness or feeling 'ill-at-ease'), headache, muscle aches and fever.

People exposed often begin to feel sick a few hours after their exposure, and may feel quite sick as they go to bed at night.

'Farmer’s Lung'

"Farmer's Lung' or Farmer’s Hypersensitivity Pneumonitis (FHP) is less common and affects about 1 in 20 exposed individuals (5 percent or slightly more). Often, farmers get sick and tell their health provider about their symptoms and their illness sometimes gets misdiagnosed as FHP.

However, FHP is a delayed allergic reaction caused when sensitive people inhale dusts causing their bodies to produce antibodies. Since FHP is an allergic reaction and involves the immune system, each new FHP bout gets worse. With repeated exposure, some people become unable to work in dusty areas and can develop permanent lung damage.

FHP is caused by dust that contains mold, mold spores and bacteria that developed in warm storage conditions. Heat-loving molds are more likely to grow in stored hay or top layers of silage. FHP molds can also occur in stored grain. If you’ve been diagnosed with FHP before, and get sick again while working around grain (or hay/silage), you should visit your local clinic.

Organic Dust Toxic Syndrome

Organic Dust Toxic Syndrome (ODTS), is a toxic reaction. With ODTS, your respiratory system becomes inflamed from the dust, molds, bacteria and endotoxins in dust. Symptoms look like FHP. But, the body’s reaction causing symptoms is different. People who develop ODTS usually recover in a few days. Permanent lung damage from ODTS is rare.

Agricultural health experts face a difficult problem, as Farmer’s Lung and Organic Dust Toxic Syndrome look almost identical. At times, even rural health professionals can have a hard time recognizing these illnesses and knowing the difference. Medical testing is often needed to truly tell the two apart. Medical treatment is also different.

Harold Hutchinson wears a dust mask to keep airborne particles from making their way inside his lungs.

Grain dust exposure and related health symptoms are complex. Here are specific things to reduce risk:

  • Have a clean air filter in place when operating a combine.
  • Avoid exposures to dust whenever possible.
  • Properly adjust your combine to minimize grain damage and dust generated.
  • Wear a NIOSH-approved 'N-95' dust mask that fits properly in conditions where dust is unavoidable.
  • If you feel sick, call your health care provider.
  • Smoking makes grain dust exposure symptoms much worse.
John Shutske

Shutske is an agricultural engineering specialist for UW-Madison and UW-Extension.