Dust isn’t just in the wind

Throughout their lives, farmers inhale a lot of dust. Field work, feed handling, working in enclosed spaces and other routine farm tasks result in dust inhalation. The type of dust, length of exposure and other factors determine the degree of risk.

Tara Nordgren, Ph.D., associate professor, University of Nebraska Medical Center, studies the short- and long-term health effects of agricultural dust exposure.

“Farms are dusty,” Nordgren said. “It isn’t just dirt. Exposure can lead to immediate, short-term symptoms and can impact long-term health.”

Dry manure, planting, harvest, grain handling, feed mixing, drying processes and storage operations produce significant amounts of dust. Farmers who work in confined spaces, such as in the access area of an upright silo, experience higher levels of dust exposure and increased risk for health problems. In addition to primary farmworkers’ direct exposure to dust, farm family members and sometimes neighbors are also exposed.

Weather can impact dust exposure. Dry conditions in late summer and autumn, especially at harvest and in combination with wind, create hazardous environmental conditions resulting in higher dust levels and potential exposure.

“The dose makes the poison,” Nordgren said. “It isn’t just the concentration of dust; it’s also how much exposure. Long work periods or multiple exposures throughout the day and week increase risk. Visible dust is a clear indicator of exposure, but some of the finest dust particles are small enough that you can’t see them. Just because you can’t see it doesn’t mean it isn’t there.”

Most dust in farming environments is organic because it contains products of living organisms. Organic dust can include plant debris, pollens, mold spores, animal dander, insect parts and soil particles, often in combination. Any of these components can trigger inflammation and allergies.

Particulate size, measured in microns, helps illustrate the risk from dust exposure. While human hair measures 50 to 70 microns and fine beach sand is 90 microns, some farm dust measures 10 microns or less. Sources of dust 10 microns and under include agriculture, wildfires, waste burning and pollen. Dust particles of this size that land on the surfaces of larger airways can result in tissue damage and inflammation.

Some agricultural dust measures 2.5 microns and smaller. These superfine particles can penetrate deeper into the lungs and enter the bloodstream. Sources include combustion products from gasoline, oil, diesel fuel or wood.

“The respiratory system begins with the nose or mouth, continues through the trachea and eventually into bronchial areas and alveolar areas of the lungs,” Nordgren said. “This is where gas exchange occurs – oxygen crossover into the bloodstream.”

The airway’s epithelial lining is designed to protect against inhaled substances. Cilia are projections in the epithelial lining, and these projections along with a mucous layer push dust up and out of the airway. These particles come out of the trachea and are coughed out or swallowed.

Although the body does a good job removing foreign particles, there’s a point at which natural defenses aren’t sufficient. Most farmers know at least one fellow farmer who has chronic obstructive pulmonary disease (COPD). This condition is the result of damage due to long-term exposure to smoke, dust, chemicals and other irritants that damage the lungs. Dust exposure is associated with increased risk of COPD.

“Livestock farmers are at higher risk than crop farmers for developing COPD,” Nordgren said. “The kind of work and the kind of dust being generated matter and can influence health in different ways.”

COPD reduces lung function and causes permanent airway damage. It’s progressive and not fully reversible. Treatment for COPD helps with symptoms but doesn’t change the decline in lung function.

Smoking is a known factor for increased risk of COPD and other chronic lung issues. Smoke damages the epithelial lining in the lungs and impairs the ability to clear particles or pathogens in the lungs.

Nordgren referenced studies suggesting that the combination of alcohol misuse and agricultural dust results in a depressed immune response and deficiencies in lung clearance that can reduce protection against infection.

Organic dust toxic syndrome (ODTS) can follow a short but heavy exposure, often four to 12 hours after the exposure. ODTS manifests with flu-like symptoms such as fever, chills, headache and muscle aches.

Hypersensitivity pneumonitis, sometimes called farmer’s lung, is an immune-mediated lung inflammation often associated with exposure to moldy hay or grain. Although exposure can result in immediate discomfort, symptoms may develop gradually over many years.

“Agricultural dust exposures have been linked to other systemic diseases such as gut health disruption, cardiovascular disease and autoimmune or rheumatic diseases, and can impact brain health,” Nordgren said. “Damage can accumulate silently, so early prevention and detection matter.”

Farmers can prevent dust damage to their lungs and other body systems. Although it isn’t always practical, watch the weather for dry, windy conditions that generate excess dust and avoid working in such conditions when possible. Enclosed tractor and other equipment cabs along with filtered air and dust suppression systems can also help. Change clothes after working in dust, wash hands prior to eating and shower after heavy exposure.

Limit workers’ dust exposure by limiting work time in dusty areas or switching out workers. Ensure buildings and confined areas have adequate ventilation. Provide appropriate dust protection respirators and/or masks and training for those working in dusty environments. Change or discard filters and masks according to manufacturer’s instructions.

Farmers doing field work, baling, harvesting, ensiling, feed handling and grain handling can decrease the risk of lung damage by dust exposure. Dust generated from routine ag operations is inevitable, but excess exposure can be prevented with fit-tested respiratory protection that’s suitable for the task and level of dust exposure.

Youth who work on farms are often assigned tasks that generate dust, including moving livestock outdoors, handling feed, cleaning pens and assisting others with tasks. Farm managers have a responsibility to foster a safe environment in which hazards that can affect lungs are recognized and mitigated.

by Sally Colby