Many harmful air-borne contaminants exist on farms and ranches, i.e., pesticides, dusts, anhydrous ammonia, etc. Worker protection from air-borne contaminants can be accomplished in a variety of ways:
In some work situations, substituting a less toxic material, engineering and administrative controls are not feasible. In these instances, personal protection is the best line of defense.
Several types of personal protective equipment (PPE) are available for use on the farm or ranch. These include respirators, goggles, headgear, boots or shoes, aprons, gloves and clothing. To be effective and be capable of protecting you against the specific contaminant, the PPE must be clean, fit properly and be in good working order.
of rules to protect you and your employees:
Types of Respirators
There are two basic types of air-purifying respirators, disposable and reusable. The disposable respirator comes in two types. The most common disposable respirator is the dust filter mask. Use a dust filter mask whenever suspended dust particles are in the air, which occurs during haying, combining, cultivation of dusty fields, the clean-up of dusty barns and when applying lime and fertilizers. The only recommended dust filter mask has two straps and a tested and certified number (TC#). Placement of the two straps gives a much better fit. Masks with only one strap typically don't provide a seal. Fibrous material used in the dust filter mask physically traps particles. This type of respirator (dust mask) does not protect against chemical vapors, gases, toxic pesticide sprays or lack of oxygen. The other type of disposable respirator looks similar to the half-mask (covers the nose and the mouth), cartridge type, reusable respirators; but the cartridge cannot be replaced.
Reusable air-purifying respirators have replaceable filter cartridges. The most common facial types are the half and full face masks. A full face mask covers the nose, mouth and the eyes. If the hazard irritates the skin or eyes, use a full face respirator. Respirator cartridges can be changed with other hazard cartridge types to fit the hazard (i.e., a particulate cartridge to a gases and vapors cartridge). Some cartridges come with pre-filters to use with the respirator cartridge. Don't forget to use them. If you don't use them, you reduce the amount of protection available to you. Cartridges or respirators from one manufacturer cannot be used with cartridges/respirators from another manufacturer. Reusable air-purifying respirators are the type commonly used to protect the user from chemical vapors, dusts and mists. Cartridge type air-purifying respirators do not protect from lack of oxygen.
Selection and Use
Air-purifying respirators offer adequate protection against many common agricultural respiratory hazards. Specific limitations that govern the use of these respirators are prior knowledge of the contaminant, the general air quality and the physical surroundings.
There are many considerations during evaluation, selection and use of air-purifying respirators: correct respirator selection, proper fit, necessary regular maintenance, and an assessment of the situation where the respirators will be used. Disregarding any of these items may result in a danger for the wearer due to a false confidence in the respirator's ability to protect. The user of an air-purifying respirator must understand its limitations and recognize situations that require more extensive protection.
Never use air-purifying respirators when:
As a rule, if the label does not specify maximum concentrations, do not wear the respirator in atmospheres containing more than five times the allowable concentration of a contaminant. For example: if a safe TLV is 5 (in any unit), never use air-purifying respirators when the concentration goes above 25 units. Knowledge of the air-borne concentration of a contaminant is needed to select proper protection.
With those severe limitations in mind, evaluate each work situation before choosing a respirator. Select a specific respirator designed to function safely within the boundaries you determine. If there is no respirator that fits the limits you select, reevaluate your selection. Never use an unapproved respirator; your life may depend on it.
Respirators work by using either a chemical or mechanical filtration system. Chemical cartridges use specially treated activated charcoal or other substances that have a high absorption capacity. Mechanical filter elements provide protection against particulate matter such as dust, mists or metal fumes. Mechanical filters work by physically trapping particulate matter. Unlike chemical filters, mechanical filters become more efficient with use, but make it harder to breathe. Therefore, change them when breathing becomes difficult. Change chemical filters periodically or when the odor of the contaminant is detected. The time to change filters depends on contaminant concentration and breathing rate of the user.
Testing for Fit
Improper facial fit negates respirator effectiveness. More than one brand and size of a particular type of face piece are available. Therefore, the first task is that the user must understand what a properly fitting face piece is. A properly fitting face piece can be determined with a fitting test. The fitting test uses banana oil, a pungent but non-hazardous oil or irritant smoke, etc. You must use the correct cartridge for the contaminant. If you can smell the test substance with the respirator on, then the face piece does not fit properly. Secondly, the user selects the brand that fits properly.
Test different brands of respirators to ensure the best possible fit before purchasing. This is the only way to protect yourself and your employees. When using respirators: make sure the respirator is not deformed; avoid excessive facial hair that may prevent a proper seal; any odor, skin or eye irritation can be an indication of possible leakage.
Features, Advantages and Limitations
The following can be used to compare the features, advantages and limitations of air-purifying respirators.
All chemical cartridges and filters are color coded to reference cartridges to specific applications. Although all manufacturers use color coding, cartridges from one manufacturer are not interchangeable with cartridges from another manufacturer. The following are the color codes:
Publication #: 5.02
Cooperative Extension, Colorado State University. Published September 1993. Copyright 1993. For more information, contact your county Cooperative Extension office.
Mac Legault, Colorado State University Cooperative Extension agricultural safety coordinator and research associate; Paul Ayers, Cooperative Extension engineer and associate professor; agricultural and chemical engineering.
Disclaimer and Reproduction Information: Information in NASD does not represent NIOSH policy. Information included in NASD appears by permission of the author and/or copyright holder. More