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Health Hazards Of Grain Dust

Date Posted: October 13, 1998

Of all the physical hazards associated with the handling of grain, inhalation of grain dust is often overlooked. However, the hazard exists, even if it is not readily recognized.

Grain dust often contains a variety of material that can damage a person's lungs. Grain dust is a complex mixture of organic material, consisting of husk particles, cellulose, and starch granules. The dust also may include pollens, grain smuts and rusts, bacteria and fungi from spoiled grain, aflatoxin, insect and mite parts, rat hairs, and silica. Grain that has been treated with pesticides may contain dangerous levels of chemicals.

Illnesses from inhalation of grain dust can range from mild irritation in the lungs to permanent lung damage or, in some situations, death.

Health Effects

A common response to breathing grain dust is chronic, or long-term, bronchitis. Bronchitis causes an inflammation of the airways that makes breathing difficult. It results in the coughing of phlegm, mucus, or sputum from the chest and may be accompanies by sneezing. Chronic bronchitis can also induce or worsen asthmatic reactions in some people.

Some workers may develop grain fever. This is characterized by flu-like symptoms of coughing, fever, chills, and body aches that develop 4 to 8 hours after exposure to grain dust. Grain fever usually occurs when a person is exposed to dust after not handling grain for a period of time.

Breathing grain dust that contains mold spores can cause a serious reaction in the lungs. Initial exposure can result in symptoms similar to those of grain fever, except that the body develops a hypersensitivity to the mold. Repeated exposures, even a year after the initial contact, can result in a serious allergic reaction, often called farmer's lung. This can lead to several weeks of illness, hospitalization, permanent lung damage, and in very serious cases, death.

Selecting a Dust Respirator

Many grain workers often wear a nuisance dust mask to prevent inhaling grain dust. It consists of a thin paper filter that is held to the wearer's head by a strap. However, this type of mask is not very effective in filtering out fine dust particles that travel deep into the lungs and are the most irritating and potentially damaging.

The first line of defense against exposure to grain dust is wearing an effective respirator. The recommended equipment to prevent grain dust inhalation is a toxic dust respirator. It must be approved for that use by the National Institute for Occupational Safety and Health (NIOSH). All approved equipment will have an NIOSH identification number with a "TC" prefix on the mask.

Several types of respirators are available for protection against grain dust inhalation: disposable mechanical filter respirators, mechanical filter respirators, and powered air-purifying respirators.

Disposable mechanical filter respirators, or dust masks, use filter materials that are held to the wearer's face by two head straps. The straps may or may not be adjustable. The filter becomes more efficient with use because the trapped particles cause it to become more dense. Breathing resistance will increase with use. The respirator should be discarded when breathing becomes difficult.

Mechanical filter respirators work similarly to the disposable kind. The main differences are that filters are normally replaceable and the face pieces are made of long-wearing materials such as flexible molded rubber, silicon rubber, vinyl, or plastic. A dust cartridge or filter also may be obtained for use with a chemical cartridge respirator, commonly used when handling pesticides. The basic mask is interchangeable for use with either the chemical cartridges or mechanical dust filters.

All mechanical filter respirators, both disposable and nondisposable types, can be purchased with an exhalation valve. This feature allows exhaled air to be discharged from the ask, which substantially adds to the comfort of wearing the mask. It is important to note that getting a good deal on the wearer's face with a mast-type respirator is impossible if the wearer has a beard or sideburns. A beard or long sideburns will not allow the respirator to seal tightly to the skin, which is necessary for effective protection against grain dust inhalation.

Powered air-purifying respirators are the most sophisticated dust respirators. They blow filtered air into a face mask with a rechargeable battery-powered unit. Unlike all other dust respirators, there is no breathing resistance. Other advantages include a constant flow of air over the wearer's face and an easy fit. By blowing air down across the face, dust particles cannot enter the breathing zone, thus making it an excellent respirator.

Several different respirators may have to be tried for proper fit. The respirator should not fit so tight as to leave red marks or indentations on the face. It should have a good seal to keep outside air from getting into the face piece. Beards or heavy sideburns may loosen that seal. Likewise, chewing gum or tobacco may also hamper the seal.

Provisions should be made for use of prescription glasses while the respirator is worn. Dust and chemicals can irritate contact lens wearers. Wearing contact lenses should be avoided because the lens could pop out and the first reaction would be to remove the respirator to put the lungs back, resulting in exposure to the toxic atmosphere.

Nondisposable respirators should be cleaned, inspected, and properly stored after each use. The respirator should be disinfected, especially if it is to be worn by someone else. Cleaning with warm water and a detergent will remove excess dust and particles. The respirator should be stored in a plastic bag or protected place.

Depending upon the features obtained and durability of the material used, these respirators are the most expensive of the three types. Regular maintenance of the equipment provides an opportunity to find damaged parts, such as broken or loose straps, dirty filters, cracked or torn face pieces, and damaged exhalation valves.

In many rural areas, approved dust respirators may be difficult to locate. However, most larger cities have safety equipment supply dealers who sell respirators. A quick check of area yellow pages in a telephone directory under "safety products" or "safety equipment" should locate the nearest supplier. In addition, many grain elevators carry or can order this equipment.

The important thing is to eliminate or significantly reduce exposure to breathing grain dust. Your good health may depend on it.

Published by Cooperatie Extension Service, Iowa State University, Ames, IA 50011.