Efforts to keep yourself and your workers safe should include a look at potential respiratory hazards anyone who works on a dairy farm may encounter. Dairy producers are routinely exposed to a wide variety of respiratory hazards on the farm, including dusts, molds, vapors and gases. Let’s explore some of the primary risks including grain dust, manure storage and farm chemicals, along with steps you should take to keep lungs healthy.

Versweyveld jim
Farm Management Outreach Specialist / University of Wisconsin – Madison / Division of Extension
Shutske john
Professor and Extension Specialist / University of Wisconsin - Madison

Grain dust 

The dust created during grain harvest, storage and handling presents possible health risks on dairy farms. Dairy farm workers can be exposed to hazardous levels of grain dust while combining, unloading, during drying and processing, in storage bins or when grinding and mixing the grain with other feed products.

Exposure to small concentrations during normal working conditions typically causes little more than nuisance reactions such as sneezing, runny nose or scratchy throat. However, in some cases, bigger health problems occur. 

Chronic and acute bronchitis is not uncommon for those who handle grain. Bronchitis occurs as lung passages get inflamed. Grain dust can also be 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
  • Fever

People exposed to clouds of grain dust often begin to feel sick within a few hours of exposure. The two conditions are “farmer’s lung” or farmer’s hypersensitivity pneumonitis (FHP), and organic dust toxic syndrome (ODTS).

“Farmer’s lung” or farmer’s hypersensitivity pneumonitis (FHP) is less common and affects about 1 in 20 exposed individuals (5% or slightly more). FHP is caused by dust containing 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 but can also be present in stored grain.

Organic dust toxic syndrome or ODTS, the second type of illness, is a toxic reaction. With ODTS, your respiratory system becomes inflamed from the dust, molds, bacteria and endotoxins in dust. Symptoms of ODTS look like FHP; however, 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 (FHP) and organic dust toxic syndrome (ODTS) 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 tell the two apart. Medical treatment is also different, so medical attention and accurate diagnosis is critical.

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. Use correct settings on the cab blower when the heater or A/C is being used to create a positive pressure.

  • Avoid exposures to dust whenever possible, regardless of your sensitivity. When combining, stay in the cab with the door closed while unloading.

  • Wear a NIOSH-approved “N-95” dust mask that fits properly in conditions where dust is unavoidable. CAUTION: Wear a respirator only if you are free of health problems, particularly with your heart and lungs. If you need extra protection, a powered air purifying respirator (PAPR) or “air helmet” can be used in these situations. There are other regulatory requirements in commercial grain storage facilities and larger farms. So producers should consult with workplace safety experts before requiring employees to use respirators.

Manure storage and collection

Primary respiratory hazards from manure storage include the gases generated during decomposition. These include gases that are toxic (hydrogen sulfide), highly irritating (ammonia), asphyxiant (carbon dioxide) and explosive (methane).

  • Hydrogen sulfide is colorless, heavier than air and will cause death within seconds at high concentrations. Hydrogen sulfide is identified by a rotten egg odor; however, the sense of smell is deadened from lower concentrations, leading people to not recognize the dangers they are facing until it is too late. The amount of hydrogen sulfide gas can increase dramatically during agitation and emptying of any volume of liquid manure, including in pits or other storage locations. Hydrogen sulfide is implicated as the cause of death of most fatalities from manure storages.

  • Carbon dioxide is a non-toxic gas, but it does replace oxygen and therefore can asphyxiate humans and animals. Because it is colorless and odorless, carbon dioxide and the adequacy of breathable oxygen is impossible to detect without gas detection equipment.

  • Ammonia can cause severe damage to the eyes, throat and lungs. In dairy and livestock buildings, it becomes a bigger issue with longer-term exposure. This gas combines with moisture in the eyes and respiratory tract, which results in severe burns. Ammonia levels in animal buildings are an important indicator of overall air quality, and a high level can indicate needed changes in air flow and ventilation system function.

  • Methane is a highly flammable and explosive gas. Methane is also odorless and colorless, and impossible to detect without gas detection instruments. While methane is lighter than air and readily rises out of storage areas, it can collect under roofs. Similar to other manure gases, it is released as manure is agitated or moved, similar to the gas released when you shake a can of soda. Methane will most likely accumulate during hot weather if ventilation is poor. In addition to being a potential asphyxiant, a buildup of methane can also cause a building explosion or fire.

All of these gases may be present with covered or non-covered pit-type storages. Danger is most severe when manure is being agitated or pumped out, and after emptying if the pit is covered.

Safety considerations:

  • Always treat a manure pit as a potentially dangerous confined space. Confined space entry is complex and requires a carefully thought through protocol, air monitoring equipment, maximum ventilation and appropriate respiratory protection. Typical masks used for dust and pesticides do not protect people from manure gases – only a self-contained breathing apparatus will protect users exposed to these gases.

  • During times when pits under or immediately adjacent to buildings are pumped or agitated, animals and people should be removed. Consult with experts on recommended ventilation rates to protect both people and animals.

  • Do not agitate, pump or move slurry or liquid manure from outdoor manure storage during periods of no wind or low wind.

  • Since hydrogen sulfide is heavier than air, always avoid setting up and operating pumping and agitation equipment in lower-lying areas or any area where moving air might settle or collect. 

  • For outside storage pumping, even during times when significant wind is present, wind direction is critical. Wind must be blowing away from workers, operators of agitators, animals and other people.

  • Use a portable, battery-powered, four-gas monitor that can provide an alarm (audible and visual) for H2S, measurement to ensure adequate oxygen levels and presence of flammable/explosive gas (generally methane in this case).

While the topic of manure gas safety has been discussed at length for many years, dairy managers should always consider new generations of children, farm employees, visitors and others involved in the industry and rural communities who may have limited knowledge of the risks and hazards that exist. 

Dairy chemical exposures

There are many safe and useful chemicals that have become integral to dairy operations. When used properly, they are an important aspect of herd health and the production of premium milk products. However, when used carelessly or “off label,” they can present a risk to workers. Chemicals like teat dips, sanitizing acids and detergents, and footbath treatments are abundant on dairy farms but can be hazardous when not used properly. Always have safety data sheets readily available for every chemical used on your farm and include them in training discussions with employees.

Remember that, unlike protecting from dusts, N95 or other dust masks provide no protection from farm chemicals. For times when exposure levels to these chemicals present a risk, properly fitted respirators with appropriate chemical cartridges are necessary. See safety data sheets for specific respiratory protection.

Changing profile of dairy workers

While chronic and short-term lung issues including respiratory disease have been recognized among dairy workers for decades, the profile of dairy workers has changed over that time period. As dairy operations have grown larger, the workforce has expanded to include many individuals who have not previously worked on farms. These increased workforce demands on expanding modern dairies may put inexperienced workers at greater risk for developing respiratory problems due to lack of hazard awareness and inadequate training.

Call to action

Dairy managers can reduce risk of lung injury and disease through:

  • Identify farm operations with potentially high dust exposures as well as other airborne hazards described in this article.

  • Implement control strategies that can reduce or remove worker exposure. Efforts to improve air quality and reduce exposures through ventilation and air movement will also benefit animals.

  • Encourage workers to seek medical care to detect lung problems early and prevent or reduce worsening of lung disease. Medical professionals can also be excellent sources of information on appropriate respiratory protection.

  • Train workers on the risks, use of exposure reduction strategies and the proper use of personal protective equipment (PPE), including ensuring that respiratory protection is matched to the hazard and fits and is used properly.

By being aware of the potential hazards and recommended PPE, producers can reduce their risk of developing serious respiratory health conditions and keep everyone on the dairy breathing easy.