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| PERSONAL PROTECTIVE EQUIPMENT (Part III)
I. INTRODUCTION Although agricultural workers are commonly exposed to a vast array of agents that threaten their respiratory health, use of respirators in potentially threatening situations is not common. The few available statistics suggest that only 8.3% of hog farmers with nonconfinement operations, for example, ever wear a dust mask, although half of the workers in swine confinement units at least occasionally wear a dust mask (K.J. Donham, D.V.M., unpublished data, April 1982). Observation suggests that workers in feed mills, grain elevators and terminals, and farm supply companies also occasionally use respirators, and that professional pesticide applicators are some of the few agricultural workers who routinely wear respirators. Fortunately, there appears to be a growing interest in personal protective equipment among agricultural workers, probably resulting from greater knowledge of agricultural respiratory hazards. This heightened awareness is reflected in the increasing number of articles, advertisements, agricultural extension service publications, and other literature focussing on respiratory hazards and respirators. Unfortunately, farmers who try to purchase respirators often discover that a network of distributors is lacking in rural areas, and that only limited equipment is available locally. As a result, farmers may increasingly turn to rural health care providers to ask why they should wear respirators, in what situations, and what specific equipment should be used. Physicians and other health care workers will do much to protect the health of the agricultural work force by encouraging proper and safe use of respirators. Because selection and use of respirators is a complex process requiring consideration of numerous variables, with medical considerations being significant among these, health care providers will benefit from a basic understanding of respirators. This unit provides guidelines for helping farm patients select and use respirators, including information on medically evaluating patients for respirator use. Supplementing these guidelines are descriptions of the various personal respiratory protective devices on the market, and a resource section which includes respirator purchase information. II. TYPES OF RESPIRATORS The following description of respirator types serves as an introduction to respirators. More specific information is available from manufacturers and other resources listed at the end of this unit. The National Institute for Occupational Safety and Health (NIOSH) and the Ivine Safety and Health Administration (MSHA) jointly approve respirators. Any respirator selected for use should have a NIOSH/MSHA approval number ("TC-xxxx") noted on the packaging and mask. (See Fig. 1) Devices are tested under laboratory conditions and approved for protection against specific substances in specific concentrations. (Note that these tests reflect industrial exposures, and are not likely to match exposure circumstances of a farm.) Approval is given for a class of chemicals or agents, for example organic vapors. All respirators have limits to the amount and to the duration of protection they can provide. Respirator users should thoroughly read, understand, and follow the manufacturer's instructions included with the respirator. Physicians should impress on their farming patients that proper use is as essential to respirator functioning as it is to any of their other equipment. Respirators are usually divided into two categories: Air-purifying respirators remove contaminants from the air around the wearer. They DO NOT provide oxygen. Air-supplying respirators provide cle~n, uncontaminated air from a source other than the wearer's environment. Most farmers and ranchers do not have a routine need for such a respirator.
Air-purifying respirators are issued with several precautions that should always be kept in mind. Since they do not supply air, they cannot be used in oxygen-deficient atmospheres (less than 19.5% oxygen, such as in an airtight silo). They cannot be used in any situation that is immediately dangerous to life and health (IDLH) (such as a freshly-filled silo or manure pit where gases could quickly incapacitate a victim), or when a contaminant has poor warning qualities (no odor or an odor that rapidly disappears, such as H2S from liquid manure). Because air must be drawn through a filter or cartridge, all air-purifying respirators (except powered ones) offer some degree of breathing resistance. This is an important medical as well as psychological consideration, and will be discussed in Section ll. Air-purifying respirators (with the notable exception of some powered air-purifying respirators) have a tight-fitting facepiece. There are three basic facepieces: quarter-masks, half masks, and full facepieces. The full facepiece has a lens or eyepiece that, when approved, has met impact and penetration standards. It is more expensive than the quarterand half-mask types. Face masks are made of flexible molded rubber, silicon rubber, vinyl, or plastic. They are attached to the head by two or more rubber or woven straps. Some of the powered air-purifying respirators have loosefitting head coverings, helmets, or face shields (see As) The air-purifying devices can be divided for convenient discussion into several types: A1 disposable mechanical filter respirators; A2 mechanical filter respirators; A3 chemical cartridge respirators; A4 gas masks; and A5 powered air-purifying respirators. A1 Disposable mechanical filter respirators are often called "dust masks" or particulate respirators. They consist basically of a shaped piece of filter material held onto a wearer's head by one or two straps. (See Fig. 2) (One-strap models often sold in stores frequented by farmers/ ranchers are not recommended as they cannot provide as good a fit as two-strap models.) These respirators protect against airborne particles by trapping them mechanically in the filter medium. The filter becomes more efficient with use because the trapped particles cause it to become denser. Breathing resistance also increases with use, and the respirator is ready to be discarded when that resistance becomes too great, or when absorbed moisture causes filter to lose its "shape". Several kinds of mechanical filters are approved by NIOSH/MSHA. The filter packaging lists the substances, particle size, and concentration for which the filter is approved. There are filters that protect against dusts and mists; against dusts, fumes, and mists; and against dusts, fumes, mists, and radionuclides. A2 Mechanical filter respirators remove the same particles in the same way as do the disposable filter respirators. However, filters in these nondisposable respirators are replaceable, and the facepieces are made to last a long time. Filter life is usually longer than that of the disposables. Filters must be replaced when breathing resistance becomes too great. Nondisposable mechanical filter respirators require proper cleaning and maintenance. A3 Chemical cartridge respirators can be either half-mask or full facepiece. (See Fig. 3) They protect against specific gases and vapors, or against narrowly defined classes of gases or vapors, through use of replaceable cartridges containing a chemical sorbent. All NIOSH/MSHA approved cartridges are color coded according to a code established by the American National Standards Institute (ANSI). Chemical cartridge respirators may also have a particulate filter cartridge, thereby being converted to a good-fitting mechanical filter respirator. Most also have particulate pre-filters that may be changed independently of the chemical cartridge. Since the particulate filter often needs changing before the cartridge, it is advantageous to have the two separately replaceable. A relatively new type of chemical cartridge respirator is disposable after the cartridge is spent. Manufacturers call these respirators "maintenance-free", but they must be checked for defects before each use. They also have replaceable pre-filters that attach to the cartridge. The entire mask is ANSI color coded. In contrast to mechanical filters, which become more efficient with use, chemical cartridges become less efficient. After the sorbent is completely utilized, gas or vapor will pass on through the cartridge. This is known as breakthrough and the cartridge must be changed immediately. Break-through may be detected by the respirator wearer upon noticing odor, taste, dizziness, or irritation. The necessity of detecting break-through by its odor before acceptable levels of gas within the mask are exceeded explains why air-purifying respirators are not recommended for use against chemicals with poor warning properties. When purchasing an air-purifying respirator for farm or ranch use, it may be a good idea to consider a basic mask unit to which a chemical cartridge, mechanical filter, or both may be added. This would increase the respirator's flexibility in varied farm situations. Cartridge respirators have a full line of cartridges available: different brands of masks and/or cartridges should not be mixed (and, in fact, will usually not have compatible fittings). A4 Gas masks also are for use against gases and vapors. They are often put in a separate category from the chemical cartridge respirators because gas masks have cansisters which are larger than cartridges. (See Fig. 5) The canisters contain a larger volume of sorbent than do cartridges, and may be used either in higher gas or vapor concentrations or for longer periods of time than chemical cartridges before break-through occurs. For the same type of canister and cartridge, the degree of protection will be determined as much by the type of mask and its fit as by the volume of chemical sorbent. Gas masks have a full facepiece with attached hose leading to a canister mounted on the wearer's belt. Chin-type canisters (with somewhat smaller capacities) are also available. Canisters are color-coded with the same ANSI code used for chemical cartridges. Like all air-purifying devices, gas masks are not for use in oxygen-deficient or IDLH atmospheres. As Powered air-purifying respirators are the newest kind of air-purifying respirators. (See Fig. 6) With a motor unit, they blow filtered air into a facepiece. In contrast to all other air-purifying respirators, there is no breathing resistance. Other advantages include a constant flow of cool air over the wearer's head and face, and an easy fit. Since powered air-purifying respirators provide constant positive pressure, they do not require a positive face seal (except with a full facepiece). Thus, they can accommodate beards, sideburns, and different sized heads, which other air-purifying respirators cannot do. Facepieces may be full face or half-mask as in traditional respirators, but, more commonly, the headgear consists of a hard helmet with either an acetate visor or an impact-resistant rigid visor. Many combinations of helmets and visors are available; there are also some nonrigid head covers. Most units are powered by a battery pack strapped to the wearer's waist or back. Batteries are rechargeable, or D-cell. An option for some units is a 12V or 24V DC adapter, allowing the motor to be run by a vehicle battery for use in tractor cabs or combines. Some smaller, ligher-weight units have mechanical filters only. In most, a replaceable filter and pre-filter, as well as fan and motor assembly, are in the helmet itself. Some units with mechanical filters have fan, motor, filters, and batteries attached at the wearer's waist and blow purified air through a hose into the headgear. Still another model must be mounted, either in a workplace or on a vehicle. A long hose from the motor/filter assembly to the headpiece allows some worker movement. Some manufacturers are advertising powered respirators for the agricultural community. Table 1 briefly compares types of air-purifying respirators. Table 2 lists many air-purifying respirators. B. Air-supplying respirators These respirators, unlike air-purifying devices, provide clean, uncontaminated air from a source outside the wearer's environment. They are designed to be used in oxygen-deficient atmospheres and some may be used in IDLH atmospheres. Most farmers and ranchers would have little use for such a respirator: in most cases it would be hard to justify the cost of such equipment, which would be intended only for emergency or rescue use. In addition, the airsupplying respirators require careful maintenance and use, necessitating training for the wearer. Briefly, air-supplying respirators are of two basic types: B1 supplied air respirators; and B2 self-contained breathing apparatus (SCBA). B1 Supplied air respirators are either air line or hose mask types. Air line devices use a stationary source of compressed air which is delivered through a high-pressure hose. These respirators have half-mask or full facepieces, helmets, hoods, or a complete suit. Air line respirators supply air on demand (requiring the user to create a slight negative pressure through inhalation), by pressure demand (always at a slight positive pressure within the facepiece), or by continuous flow (the unit constantly feeds air into helmets, hoods, or suits). The highest degree of protection is offered by the pressure demand and continuous flow types, both of which are positive pressure systems. They can be worn for long, continuous periods of time. However, they cannot be worn in IDLH atmospheres because the wearer is too dependent on the air supply hose and source: if something were to happen to either, the wearer might not have enough escape time. Another type of supplied air respirator is the hose mask. These deliver air from an uncontaminated source to a facepiece through a large diameter hose. They do not use compressed air or pressure regulatory devices. They may or may not have a blower. Those with blowers may be used in IDLH atmospheres. B2 A self-contained breathing apparatus allows the user to carry up to four hours of air with him/her. (See Fig. 7) There are closed circuit SCBAs in which air is rebreathed (with oxygen added), open circuit SCBAs in which exhaled air is exhausted into the atmosphere, and combination SCBA and supplied air respirators. They may be used in IDLH atmospheres. Table 1 Comparison of Air-Purifying Respirators A1 Disposable Mechanical Filter Respirators Used for Dusts: yes ש adjustable and two-strap models available Amount of Maintenance:
low ש light weight
ש clog with moisture from wearer's breath in humid air
cause glasses to fog over in cold weather
A2 Mechanical Filter Respirators Used for Dusts: yes A3 Chemical Cartridge Respirators Used for Dusts: yes cartridge is spent
ש selecting the correct type of particulate or gas
cartridge is mandatory
. particulate pre-filters available
A4 Gas Masks Used for Dusts: yes ש correct type of canister must be selected A5 Powered Air-Purifying Respirators Used for Dusts: yes ש not recommended for protection against gases Table 2 Air-Purifying Respirators A1 Disposable Mechanical Filter Respirators Cost: The cost of respirators in this category varies from
about $.30 to $9.00 each according to the available features.
3M 8710 Dust/Mist
3M 9920 Dust/Fume/Mist Respirator
AO R1050 Dust Demon
AO R1070 Disposable
North 7170 Disposable DustlMist Respirator
U.S. Safety Softseal D
Moldex 2200 Dust and Mist Respirator
Gerson 1710 Dust and Mist Respirator
A2 Mechanical Filter Respirators Cost: The cost of respirators in this category varies from
about $12 to $20 each. The cost of filters for these
respirators starts at about $2.50 for a package of 5 filters.
North 7100V Reusable DustlMist Respirator
MSA Dustfoe 66 Respirator
MSA Dustfoe 77 Respirator
MSA Dustfoe 88 Respirator
AO R2090N DustlMist Respirator
AO Welding Fume Respirator
Pulmosan Dust Respirator
A3 Chemical Cartridge Respirators Cost: The costs of all respirators in this category except
the disposables vary from about $15 to $65 for half-mask
models to about $75 to $125 for full facepiece models.
Replacement cartridges cost from about $3.75 to $6.00 each.
3M Easi-Air
MSA Confo II Respirator
MSA Back-Mounted Respirator
MSA Belt-Mounted Respirator
MSA Ultra-Twin Respirator
U. S. Safety Series 150 (CESCO 95)
(CESCO)
U.S. Safety Series 151 (CESCO 96)
(CESCO)
Willson 1200 Series Respirators
Willson 1600 Series Respirators
Willson 1700 Series Respirators
North 100 Series Disposable
3M Maintenance-free Respirators
AO Quantifit Series Respirators
AO Commander Respirator
Survivair Blue 1 Air Purifying Respirators
Scott Model 64 Respirator
Scott Model 65 Respirator
HSC Model 1482 Respirator
Pulmosan C 200 Series Respirators
North 7700 Series Respirators
North 7600 Series Respirators
North 75 BP Series Respirators
A4 Gas Masks MSA Type N Gas Mask
Super Size Gas Mask
Industrial Size Gas Mask
Chin Type Gas Mask
Scott Model 63 Chin style Gas Mask
A5 Powored Air-Purifying Respirators Cost: The cost of respirators in this category varies from
about $155 to over $500.
Racal Breathe Easy Systems
Racal Airstream Systems
Racal Dustmaster System
3M Airhat Systems
3M Powered Air Purifiers
MSA Powered Air Purifying Respirator
Neoterik Breezer Powered Respirators
Neoterik Puriflo Powered Respirators
This is only a partial list of all the available respirators and includes models, and comparable models, on which research is currently being done to determine their effectiveness in agricultural usage. Manufacturers and vendors may direct suggestions for product additions or deletions to the American Lung Association of lowa, 1321 Walnut, Des Moines, lowa, 50309. The mention of manufacturers' names and products is solely for informational purposes and is not intended as endorsement over other comparable products, either mentioned or not mentioned, by the American Lung Association of lowa, The University of Iowa, or the Iowa State University Cooperative Extension Service. III. GUIDELINES FOR RESPIRATOR SELECTION AND USAGE Proper and effective use of personal respiratory protective equipment necessitates that hazard, respirator, and wearer by properly matched. It is possible that more harm may come to a person having inadequate respiratory protection, but assuming he/she is protected, than to a person using no protection. Farmer Smith might continue to work in his swine confinement building, ignoring respiratory disease symptoms, because he assumes that his respirator is protecting him (even though it in fact is not). Thus, use of inadequate respiratory protection would cause him to ignore warning signals and prevent him from seeking proper medical help. If farmers were employed in the industrial sector, they probably would be involved in a respiratory protection program. Because of the obvious differences between industrial and agricultural work places, procedures designed for industrial use are not directly applicable to the farm or ranch setting. Therefore, we propose a respirator use program modified from industry and adapted for use by agricultural workers. To insure the maximum safety and benefit from respirator usage, the following steps are recommended and are explained in detail in following paragraphs:
In industries employing many workers, it is economically feasible to buy and operate sophisticated air sampling equipment. In most instances, occupational health personnel know exactly what offending substances to monitor. The degree of protection required can then be determined by comparing monitored environments with government-established exposure limits. The agricultural workplace has quite a different character. People work in a variety of environments in the course of a year and are exposed to a wide range of potentially harmful substances. It would be impractical for an individual farm operation to purchase the kind of equipment necessary to continuously and accurately measure the air in the operation. However, some situations or structures (such as confinement houses) may warrant occasional or continual monitoring. Unit 8, "Measurement of Agricultural Dusts and Gases", describes air quality measurement instruments potentially useful to the farmer. Using Table 3 (in Step 4) as a guide, farmer and physician should note all potentially hazardous substances the farmer comes into contact with over a year. A list of this type will pinpoint areas of respiratory health concern. Often, farm patients will need protection against more than one class of hazard or substance. They may want to purchase the most protection possible while minimizing cost and maximizing comfort. Or, they might want to have a supply of disposable dust masks on hand as well as a respirator with interchangeable cartridges and filters. Each individual will have different needs, based on his/her farming operation. Once hazards have been documented, they should be eliminated or reduced to the extent possible. 2. Eliminate or reduce hazard by engineering and management strategies and reassess risk This is the preferred way to deal with a potential agricultural respiratory hazard. Agricultural workers may hear of a respirator and decide that its use would be an easy way to protect their respiratory health. They might think that controlling a respiratory hazard by engineering changes would be too expensive, or that management controls would make their work harder or more time-consuming. This is indeed possible, but respirators should be used as a last resort for several reasons: ש Proper respirator maintenance is essential but it may be neglected if the wearer is not properly motivated. ש Wearing any type of respirator causes a certain amount of stress and can be uncomfortable and inconvenient. ש Wearing a respirator may increase the risk of injury because of interference with vision, communication, or movement. Workers depending solely on respirators may not be protected if they are using effective equipment or if they fail to wear it when needed. In addition, elimination of the hazard is much safer both for family members or visitors and for the farmerlrancher: as long as a hazard exists, people unprotected by respiratory equipment may be accidentally exposed. For these reasons, ranchers and farmers must be encouraged first to consider effective control of the hazard itself. Each of the other units in this series gives detailed suggestions for control of specific hazards discussed in those units. In some cases, elimination of a hazard may also increase production and profit. For instance, adjusting ventilation in a swine house might produce healthier, faster-gaining animals. You and your patient should discuss these possibilities before deciding on personal respiratory protection. A reassessment of respiratory hazards should be made after reduction efforts are completed. Agricultural respiratory hazards often cannot be sufficiently controlled or avoided. Time or finances may prevent immediate changes in an existing agricultural operation. In such cases, personal respiratory protection should be employed. 3. Determine the patient's medical suitability to use respiratory protective devices Some people, for physiological or psychological reasons, should not use respirators. Other people should choose one type of respirator over another because of medical considerations. The Occupational Safety and Health Administration (OSHA), which regulates the use of respiratory protection in industry, requires potential respirator wearers to undergo an initial physical examination and periodic medical status reviews. This screening and monitoring are equally important for agricultural workers who are not covered by OSHA. Respirators increase the total work of breathing as well as the average and peak ventilation work rates, imposing burdens on the pulmonary and cardiovascular systems. Some respirators impair sight, speech, or movement. Some add enough weight to be burdensome. With these respirator features in mind, you should screen prospective respirator wearers for the following:
Other information you should consider when evaluating medical suitability includes tasks to be performed while wearing the respirator; length of time the equipment will be worn; visual and audio requirements associated with the task; estimation of the energy requirements of the task; and, the substances to which the wearer will be exposed. Psychological conditions may also limit use of respirators. People who are claustrophobic or those who do not understand the need for respirator use may not be reliable respirator users. This is especially true when the problem of discomfort arises. Some people are discouraged after trying a respirator that is uncomfortable. But by "shopping around", your patient should be able to find a style of respirator that gives adequate protection with reasonable comfort and cost. 4. Select proper respiratory protective equipment Table 3 lists agricultural respiratory hazards and agricultural tasks exposing workers to these hazards. Matched to each task or hazard are specific types of respiratory protective equipment. Only classes of respirators are suggested, not specific respirators. Farm patients will need to base their choices on availability as well as such things as medical suitability and specific hazards to be protected against. The use of airsupplying respirators by untrained farmers or ranchers is not recommended. Proper respirator fit is important. Respirator manufacturers usually provide fitting information for their product. Some respirators come in two or three sizes, some in only one size. Some general fitting considerations include:
PLEASE NOTE: THE FOLLOWING TABLE IS WIDER THAN THE SCREEN. USE THE RIGHT ARROW KEY TO VIEW THE RIGHT SIDE OF THE TABLE. TO
PRINT THE ENTIRE TABLE YOU MUST FIRST EXPORT THE TABLE
AND USE A WORD PROCESSOR OUTSIDE THE RETRIEVAL SYSTEM.
Table 3 Agricultural Respiratory Hazard Exposure Class and Constituents of Hazard Jobs Resulting in Exposure Respirator Category1/Ranking2
Working inside livestock confinement - - 1 2 3 -
structures which have liquid manure
storage under a slatted floor
C. High Levels of Toxic Gases or Oxygen-deficient Environments
N.B. For all pesticides follow the manufacturer's recommendations for all protective equipment 1 AIR-PURIFYING respirators are divided into 5 categories: A1 Disposable
mechanical filter respiratorS A2 Mechanical filter respirators AIR-SUPPLYING respirators (B) should only be used by trained people. Local volunteer fire departments may be able to suggest where a farmer or rancher could get such equipment and training. It is not recommended that farmers or ranchers attempt to use such equipment without proper training. 2 Rankings are based on a subjective priority ranking by the authors and content consultants: 1-3 is highest to lowest priority of acceptable respirators for use in the specified situation. The ranking is based on a combination of effectiveness of protection, comfort and freedom from interference to perform required tasks, and cost.
Fit of nondisposable respirators can be evaluated by quantitative and qualitative tests. Quantitative tests are more accurate but require expensive equipment and trained operators. You and your farm patient must rely on qualitative tests to determine the best fit. Qualitative tests include the negative pressure test and the positive pressure test, both of which are used for nondisposable respirators with tight-fitting facepieces. For the negative pressure test, the wearer closes off the inlet of the canister, cartridge(s), or filter(s) by covering with the palm(s). The wearer then inhales so that the facepiece collapses slightly. If after ten seconds the facepiece remains collapsed and no inward leakage is noticed, there is probably a tight seal. A drawback of this test is that wearer handling of the facepiece may reposition the facepiece and cause an improper seal. The same objection applies to the positive pressure test. Here the exhalation value is closed off and the wearer gently exhales into the facepiece. If a slight positive pressure is built up, without outward leakage, the fit is considered to be satisfactory. This test should not be used if removal and replacement of the exhalation valve cover is required. Respirators should be tested for fit before each use. 5. Establish respirator care procedures Some respirators require considerable maintenance. Others, such as disposable ones, require very little. You should be sure that your farm patient is aware of (and willing to do) the maintenance required before purchase. Manufacturers' care instructions are provided with most respirators and should be followed. Maintenance and inspection for defects is necessary for all respirators before each use. Encourage patients to check for stretched out or torn head bands; bent, broken, or missing hardware; aging or damaged exhaust and intake valves; cuts, tears, holes, melting or stiffening of facepiece; and cracks or damaged threads in the filter/cartridge housings. Wearers should also check that a respirator disassembled for cleaning has been properly reassembled. Cleaning and disinfecting are required for all but disposable respirators. Manufacturer's instructions should be followed. Proper storage means that all respirators should be protected from excess heat and humidity and stored in an uncontaminated area, in plastic zip-lock bags for instance. One other wearer responsibility is knowing when a disposable respirator or a cartridge, canister, or filter needs replacing. For dust/mist filters and respirators: replace at first when respiration becomes noticeably harder (wearer may need to try a clean filter periodically for comparison); ש replace routinely after a period based on experience For gas/vapor respirators: replace canister or cartridge upon initial odor break-through; ש replace after a routine period based on experience 6. Evaluate effectiveness You and your farm patient can note any change in the patient's respiratory
health status. How does the patient feel? If there were symptoms of respiratory
irritation or disease before respirator use was begun, have these symptoms
abated? Are any changes noted in pulmonary function tests? תתתתתתתתתתתתתתתתתתתתThe National Dairy Database (1992)תתתתתתתתתתתתתתתתתתתת תתתתתתתתתתתתתתתתתתתתת\NDB\OCCSAFE\TEXT2\OF201200.TXTתתתתתתתתתתתתתתתתתתתתתת %f TITLE;PERSONAL PROTECTIVE EQUIPMENT |
