Respiratory Illnesses Associated with Agriculture

Sunset and wind mills

Photo provided by the Central States Center for Agricultural Safety and Health (CS-CASH)


Use the following format to cite this article:

Respiratory illnesses associated with agriculture. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from


A farmer’s or rancher’s life is not always associated with the great outdoors and fresh air. In production agriculture, farmers and ranchers can be exposed to toxic gases and contaminated particulate matter that can cause short- and long-term health problems. The three main respiratory illnesses associated with production agriculture are:

  • farmer’s lung,
  • silo filler’s disease, and
  • organic dust toxicity syndrome. 

Farmer’s Lung

Farmer’s lung, or farmer’s hypersensitivity pneumonitis (FHP), is a noninfectious allergic disease that affects normal lung function. It results from the inhalation of mold spores from moldy hay, straw, or grain. The mold spores that cause farmer’s lung are microorganisms that grow in baled hay, stored grain, or silage with high moisture content (30%). Exposure to mold spores is greater in late winter and early spring.

Mold spores, which are not always visible, are so tiny that 250,000 spores can fit on the head of a pin. Because the spores are so small, it is easy for a farmer or rancher to breathe in millions of spores in a few minutes. Due to their size, the mold spores easily move into and settle in the lower part of the lungs.

Symptoms usually begin four to six hours after exposure to mold spores and can include increased coughing, coughs that bring up mucus, fever, chills, shortness of breath, discomfort in the lungs, and a tightness and/or pain in the chest. Symptoms may become most severe from 12 to 48 hours after exposure.

Allergic reaction to mold spores can be acute or chronic. An acute attack typically resembles the flu or pneumonia. Chronic reactions can resemble a nagging chest cold. A producer who has been diagnosed with farmer’s lung should avoid additional exposure to mold spores; otherwise, the producer’s condition could worsen and render him or her inactive. In some cases, farmer’s lung can be fatal.

If you think that you may have farmer’s lung, contact your physician and explain your symptoms and occupation. If your physician is not familiar with farmer’s lung, you may need to request a referral to a specialist for testing, diagnosis, and treatment.

To reduce the risk of contracting farmer’s lung, take the following steps:

  • Identify and minimize contaminants in your work environment.
  • Avoid exposure to contaminants and mold spores.
  • Limit the growth of mold spores by using mold inhibitors.
  • Harvest, bale, store, and ensile grains at the recommended moisture level to reduce mold growth.
  • Convert from a manual to a mechanical or automated feeding or feed-handling system to reduce the release of airborne mold spores.
  • Move work outside and avoid dusty work in confined areas whenever possible.
  • Mechanically remove air contaminants through ventilation with fans, exhaust blowers, and so on.
  • Wear appropriate respirators, dust masks, or other personal protective equipment (PPE). Click here to learn more about respiratory PPE.

Silo Filler’s Disease

Silo filler’s disease results from inhaling nitrogen dioxide, a silo gas produced during the silage fermentation process. Although a producer who has been exposed to silo gases may not experience symptoms, damage to the lungs may still have occurred. Fluid can build up in a person’s lungs 12 hours after exposure to nitrogen dioxide. Cough, hemoptysis (coughing up blood from the respiratory tract), dyspnea (shortness of breath), and chest pain can occur after an exposure to 20 ppm, a moderate level of nitrogen dioxide. This concentration has been designated by the National Institute for Occupational Safety and Health (NIOSH) as immediately dangerous to life and health (IDLH). Exposure to higher concentrations (greater than 100 ppm) can result in pulmonary edema (fluid accumulation in the lungs) and in swelling in the lungs, leading to long-term respiratory problems or death. Lower concentrations of 15 to 20 ppm are considered dangerous and can cause respiratory impairment.

If you have been exposed to silo gases, even a small amount, seek immediate medical attention.

To reduce exposure to nitrogen dioxide in silo gases, refrain from entering a silo for ten days to three weeks after filling is complete. If entry is necessary after the three-week period, run the silo blower for a minimum of 30 minutes prior to and during entry, and use a portable gas monitor to continually monitor the gas and oxygen levels in the silo. Click here to learn more about silo gases and how to reduce the risk of exposure.

Organic Dust Toxicity Syndrome

Organic Dust Toxicity Syndrome (ODTS), also called grain fever, toxic alveolitis, or pulmonary mycotoxicosis, is caused by exposure to very large amounts of organic dust. Certain agricultural areas may have large amounts of organic dust: grain storage, hog barns, poultry barns, and cotton-processing areas.

The onset of ODTS can occur four to six hours after exposure, and symptoms can be similar to those of acute farmer’s lung and may include cough, fever, chills, fatigue, muscle pain, and loss of appetite. People who have experienced ODTS and who experience additional exposures to organic dust have an increased risk for respiratory problems and the potential for developing chronic bronchitis. Producers can become very sick from ODTS, but most people completely recover. Occurrences of ODTS are underreported because symptoms often resemble the flu or other mild illnesses.  

You can reduce your risk of contracting ODTS by using a respirator to decrease exposure to organic dust. Click here to learn about the different types of respirators used in production agriculture. Implement best management practices to maintain good air quality in confinement buildings for swine and poultry.


Use the following format to cite this article:


Respiratory illnesses associated with agriculture. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from



Atia, A. (2004) Agri-Facts: Silo gas (NO2) safety. Alberta Agriculture, Food, and Rural Development. Retrieved from$department/deptdocs.nsf/all/agdex9036/$file/726-1.pdf?OpenElement.

Cyr, D. and Johnson, S. (2002) Upright silo safety. University of Maine Extension. Retrieved from

Farmer’s lung. (2008) Canadian Centre for Occupational Health and Safety. Retrieved from

Grisso, R., Gay, S., Hetzel, G., and Stone, B. (2009) Farmer’s lung: Causes and symptoms of mold- and dust-induced respiratory illness. Virginia Cooperative Extension. Retrieved from                                             

Kirkhorn, S. and Garry V. (2000) Agricultural lung diseases. Environmental Health Perspectives. Retrieved from

Murphy, D. (2013) Farm respiratory hazards. Pennsylvania State University Cooperative Extension. Retrieved from

Von Essen, S., Andersen, C., and Smith, L. Organic dust toxic syndrome: A noninfectious febrile illness after exposure to the hog barn environment. Journal of Swine Herd Health and Production. 2005; 13(5): 273-276. Retrieved from


Reviewed and summarized by:
Linda M. Fetzer, Pennsylvania State University –
Karen Funkenbusch, University of Missouri
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Robin Tutor-Marcom, North Carolina Agromedicine Institute
Aaron M. Yoder, University of Nebraska Medical Center –

Respiratory Protection on the Farm and Ranch

Use the following format to cite this article:

Respiratory protection for the farm and ranch. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from


Farmers and ranchers often work in areas where air quality can be less than ideal. Agricultural producers working in such conditions should wear personal protective equipment (PPE) to decrease their risk of contracting a respiratory impairment. (Click HERE to learn more about respiratory illnesses related to production agriculture.) Individuals who should use respiratory protection are those working around: 

  • dust,
  • mold spores,
  • silage,
  • fish meal,
  • agricultural chemicals,
  • solvents, and
  • toxic gases in confined animal housing.

Respiratory hazards fall into one of three categories:

  • Particulate contaminants: Dusts, mists, and fumes contaminate the air with particles that can be inhaled.
  • Gases and vapors: Gases are chemicals that are gaseous at room temperature, such as those found in silos and manure pits. Vapors are released from liquid applications, such as  pesticides and adhesives.
  • Oxygen-deficient atmosphere: Oxygen levels can be almost as low as 5% in such areas as sealed silos, manure storage facilities, and controlled atmospheric storage for fruits and vegetables.

Your respiratory protective equipment must be properly fitted for you, designed for the job that you need to complete, and specific to your work environment. A single type of respiratory protection does not fit all work situations, so it is critical to identify the appropriate type of respiratory protective equipment for each situation.

Nuisance Dust Mask

Single Strap Respirator

Single Strap Respirator

(Source: Pennsylvania State University. Agricultural Safety and Health)

A nuisance dust mask is constructed of extremely light filter paper. A single thin elastic circles your head to secure the mask. This type of mask provides protection against large dust particles, but provides little to no protection against smaller airborne particles. Wear this type of mask only if you have had no prior respiratory impairment and are completing a short-term task involving nontoxic dust, such as sweeping the floor of a garage or shop. A nuisance dust mask is not a respirator.


A respirator is a device that protects the respiratory tract. There are two types of respirators: air-purifying respirators and supplied-air respirators.

Air-Purifying Respirators

Air-purifying respirators are useful when working around moldy hay in areas such as barn lofts and during pesticide applications. This type of respirator is also called a “negative-pressure respirator” because the wearer uses his or her own breath to move air through the respirator, inhaling and pulling air through the filter. Producers who have any type of respiratory limitation, such as asthma or cardiovascular problems, should check with their physicians prior to using air-purifying respirators.

The following descriptions will help you determine the type of air-purifying respirator needed for your work.

Disposable Particulate Respirator

Double Strap Respirator

Double Strap Respirator

(Source: Pennsylvania State University. Agricultural Safety and Health)

The disposable particulate respirator is commonly referred to as a dust mask, but it should not be confused with a nuisance dust mask. Main uses for the disposable particulate respirator include protection from dusts, mists, and some fumes in jobs such as haying, applying fertilizer, and grinding feed.

The unit is a molded mask that covers the user’s nose and mouth, held in place by two elastic straps. The filter is made of fibrous material that traps particles as you inhale. This type of respirator can be disposable or reusable, but should be disposed of when saturated with a liquid. Replace the filter of a disposable mask when: 

  • breathing becomes difficult. 
  • the mask loses its shape. 
  • the mask does not seal to your face.
  • you can taste or smell a substance known to be in the air.

All particulate respirators approved under the most recent testing requirements have a certification label displaying emblems from the National Institute of Occupational Safety and Health (NIOSH) and the Department of Health and Human Services (DHHS).

Chemical Cartridge Respirators

Full Mask Chemical Cartridge Respirator

Full Mask Chemical Cartridge Respirator

(Source: Pennsylvania State University. Agricultural Safety and Health)

Chemical cartridge respirators use an absorbent material, such as activated charcoal, to absorb contaminants and filter out low concentrations of toxic gases and vapors. A chemical cartridge respirator consists of a soft, silicone facepiece that covers the nose and mouth and a valve to regulate air movement through the filter. This type of respirator is appropriate for areas that have vapors and dust because these respirators can be equipped with the necessary filters. Half-mask models can be disposable or reusable. Because a full-face mask provides eye and face protection, it offers greater protection against contaminants.

Typically, the filtering cartridge screws into the front of the mask. You can select and insert the correct cartridge for the type of gas or vapor contaminant in your work area. Cartridges are color-coded according to the type of gas or vapor contaminant they filter. Black, for example, indicates a cartridge that filters organic vapors; green, a cartridge that filters ammonia.

Replace cartridges after eight hours of use, when you begin to smell or taste the contaminant (a situation called “breakthrough”), or when dizziness or irritation occurs. Do not use a chemical cartridge respirator in areas that may contain gases designated as immediately dangerous to life or health (IDLH).

Gas Masks

A gas mask is also called a chemical canister respirator. The canister holds more chemical absorbent than a chemical cartridge, and gas masks can be used in areas where gases are extremely toxic and/or highly concentrated. The canister can be mounted on a person’s belt, worn on the back or chest, or screwed onto the mask at the chin and connected to the facepiece via an air hose.

Replace the canister of a gas mask after eight hours of use or when breakthrough occurs. This unit is a full-face piece and should not be worn in areas considered IDLH.

Powered Air-Purifying Respirators (PAPRs)


(Source: Pennsylvania State University. Agricultural Safety and Health)

Unlike a negative-pressure respirator that requires breathing to move air through a respirator, a PAPR is equipped with a motorized blower that forces air through the filtering device. For this reason, PAPRs are also called “positive-pressure respirators.” This type of respirator is recommended for individuals who have respiratory impairments or cardiovascular conditions.

Most PAPRs have a hard helmet and rigid visor, although half-masks and full-face models with nonrigid helmets are also available. A PAPR with a full-face mask or closable hood provides the greatest protection against contaminants. Depending on the filter that you are using, the PAPR can be used to provide protection against dusts, mists, gases, and vapors. With a constant flow of air, the unit is cooler for the user. The power source for a PAPR is either D batteries (disposable or rechargeable) or a 12V or 24V DC adaptor that can be powered from a vehicle battery.

This unit should not be worn in areas considered IDLH.

Supplied-Air Respirators

Supplied Air Respirator

(Source: Pennsylvania State University. Agricultural Safety and Health)

A supplied-air respirator provides the user with fresh, clean air from an outside source. The two types of supplied-air respirators are air-line respirators and self-contained breathing apparatus (SCBA). An air-line respirator provides clean air via a hose (up to 300 ft.) that is connected to a stationary air pump or tank located in a clean-air area. The SCBA has a portable air tank that is carried on the back, similar to the unit carried by a scuba diver or firefighter. 

Supplied-air respirators are very expensive and require proper fit and maintenance to operate correctly. In addition, a user should receive instructions for using this type of respirator and should practice its use.

A supplied-air respirator is the only respirator that should be worn in an area considered IDLH, such as a manure pit or sealed silo. Using a supplied-air respirator is the only safe way to enter an area considered IDLH because of potentially dangerous gas levels and lack of oxygen. As an agricultural producer, you risk your life by entering an oxygen-deficient atmosphere without a supplied-air respirator.

Filtering Efficiency

A respirator is rated according to its efficiency in reducing the user’s exposure to dust, mists, and fumes and its time-use limits against oil-based chemicals or pesticides in the air. The filter efficiency is represented by a letter—N, P, or R—followed by a percentage. The letter indicates whether the respirator is resistant to oil and for how long. The percentage indicates the filter efficiency, or the percentage of airborne contaminants the filter removes. Typical efficiencies are 95%, 99%, or 99.97%, with higher percentages having greater efficiencies. 

  • N-series respirators are not resistant to airborne oils and can plug quickly.
  • R-series respirators are resistant to airborne oils for up to eight hours.
  • P-series respirators are oilproof and, depending on the given respirator, may be resistant to airborne particles for up to eight hours. P-series filters should be changed every 40 hours or 30 days, whichever comes first.

These ratings appear on respiratory units, prefilters, cartridges, packaging, and advertisements. Some common filter efficiency labeling is shown below:

  • N95 – Particulate Filter: 95% filter efficiency against particulate aerosols free of oil
  • R99 – Particulate Filter: 99% filter efficiency against all particulate aerosols
  • P100 – Particulate Filter: 99.97% filter efficiency against all particulate aerosols

Purchasing and Maintaining Your Respirator

After you have determined the type of respirator that you need for your farm or ranch, locate suppliers in your area. Visit your local farm store, agricultural chemical dealer, or industrial safety equipment distributor to try on different brands and styles in order to select the respirator that fits your needs. If possible, have a trained person teach you how to perform a “fit test” to make sure that you have the best seal with your face.

Check the facial fit of your respirator each time that you use it to ensure that you are getting the maximum protection. Glasses, gum or tobacco chewing, and facial hair can negatively affect the seal of your respirator. If you experience a break in the seal, smell or taste a contaminant, or experience dizziness or irritation while you are wearing the respirator, leave the contaminated area immediately and enter an area with fresh air.

Never wear contact lenses when wearing your respirator because of the potential for exposure to contaminants that can stick to the lenses or damage your eyes. Adaptors for prescription eyewear are available that fit inside the facepiece of full-face respirators.

Maintain your respirator by cleaning it frequently with warm, soapy water. Be sure to remove all cartridges and filters before immersing the respirator in water. Thoroughly dry the unit and store it in a sealed plastic bag to prevent cartridges from absorbing vapors and filters from collecting dust.

Inspect your respirator regularly for damage to the facepiece or head straps, dirt around the facepiece, missing valve covers, and loss of elasticity in the head straps. Replace only those parts, such as filters and head straps, that are designed to be replaced. Contact the manufacturer or dealer concerning major part replacement and repairs.


View the video below concerning respiratory protection on the farm or ranch.


Use the following format to cite this article:


Respiratory protection for the farm and ranch. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from


General respiratory protection guidance for employers and workers. (n.d.). OSHA Bulletin. Occupational Safety and Health Administration. Retrieved from .

Grisso, R., Gay, S. W., Hetzel, G., and Stone, B. (2009) Respiratory protection in agriculture. Virginia Cooperative Extension. Retrieved from

Jester, R. & Malone, G. (2004) Respiratory health on the poultry farm. University of Delaware Cooperative Extension. Retrieved from….

Metzler, R. and Szalajda, J. (2011) NIOSH approval labels – key information to protect yourself. National Institute for Occupational Safety and Health (NIOSH). Retrieved from

Murphy, D. J., Harshman, W. C., and LaCross, C. M. (2006) Farm respiratory protection. Pennsylvania State University Cooperative Extension. Retrieved from

New classifications help match protection to hazard. (n.d.) Electronic Library of Construction Occupational Safety and Health. Retrieved from


Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University –
LaMar J. Grafft, University of Iowa
Dennis J. Murphy, Pennsylvania State University (Has since retired)
J. Samuel Steel, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center –