Quick Facts...
- Read the label or material safety data sheet (MSDS)
for the type of respiratory protection required.
- Ensure proper fit.
- Store respirators in a sealable, nonporous bag and in an area not
exposed to chemicals or other agents that may be absorbed by the respirator
cartridges.
Many harmful air-borne contaminants exist on farms and ranches, e.g., pesticides, dusts,
anhydrous ammonia, etc. Protection from air-borne contaminants can be achieved in several ways.
- Substitute non-toxic substances: replace toxic pesticides
with reduced-risk pesticides, biological control agents or mechanical/cultural
controls.
- Engineering controls: install ventilation systems
on tractor cabs and confined spaces.
- Administrative controls: rotate workers and restrict
re-entry into sprayed fields.
- Personal protective equipment: provide respirators,
dust masks and protective clothing.
In some work situations, less toxic materials, or 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. These include
respirators, goggles, headgear, boots or shoes, aprons, gloves and clothing. To be effective and
protect you against the specific contaminant, the PPE must be clean, fit properly and be in good
working order.
Air-purifying respirators function by filtering contaminants from the air. They do not
supply oxygen to the wearer. Air-purifying respirators can only protect at or below specific
concentrations of contaminants. Labeling on each air-purifying respirator carton or package
contains specific information about maximum concentrations and types of contaminants protected
by the respirator. If the labeling does not give information about maximum concentration
protection levels, contact the manufacturer or do not exceed five times the threshold limit value (TLV)2 for that contaminant. Because this is only a rule of thumb, you need to know the actual
safe exposure limit for specific hazards.
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: during haying, combining, cultivating dusty
fields, cleaning dusty barns, applying lime and fertilizers. The only
recommended dust filter mask has two straps and a tested and certified
number (TC#). Two straps give a better fit. Masks with only one strap
typically do not provide a seal. Fibrous material used in the dust filter
mask physically traps particles. This type of respirator does
not protect against chemical vapors, gases, toxic pesticide sprays
or lack of oxygen. The other type of disposable respirator looks similar
to 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 (e.g.,
a particulate cartridge to a gases and vapors cartridge). Some cartridges
come with pre-filters to use with the respirator cartridge. Do
not forget to use them. If you do not use them, you reduce the
amount of protection available to you. Cartridges or respirators from
one manufacturer cannot be used with cartridges and respirators from another
manufacturer. Reusable air-purifying respirators protect from chemical
vapors, dusts and mists. They do not protect from lack
of oxygen. Be sure to follow all label requirements.
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 for evaluation, selection and use of air-purifying
respirators: correct respirator selection, proper fit, regular maintenance, and an assessment of the
situation where the respirators will be used. Disregarding any of these items may result in danger
for the wearer due to a false confidence in the respirator's ability to protect. The user must understand its limitations and recognize situations that require more extensive protection.
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 or as directed by the manufacturer. The
time to change filters depends on contaminant concentration and breathing
rate of the user.
Never use air-purifying respirators when:
- There is a lack of oxygen. These respirators only
purify air; they do not supply oxygen. Determine lack
of oxygen, or oxygen deficiency, in one of two ways: direct
measurement equipment (these devices are available from fire
departments and many utility companies) and evaluation
(tanks, pits, storage bins and tunnels are likely to be oxygen deficient).
- Present contaminants do not have warning properties,
e.g., odor, irritant properties or taste. Many contaminants have warning
properties at high concentrations. By then it is too late. Be
careful. Odor, taste and irritation are easily determined.
Many compounds have no warning properties. However, manufacturers can
inform you of specific warning properties. Detecting contaminants that
do not have warning properties can be difficult, and the contaminant
can leak through or around a respirator and you will not know it.
- The contaminant is extremely toxic (TLV less than 1 ppm).
Consult the product label, material safety data sheet (MSDS) or the
manufacturer. Manufacturers of specific chemicals can suggest respirators
for specific compounds. Many toxic contaminants are generated in place:
hydrogen sulfide in manure pits, nitrogen dioxide in silos. For additional
information, contact your local Colorado State University Cooperative
Extension county office. For more information on air-borne hazards and
pesticide protective equipment, refer to fact sheet 5.019, Agricultural
Air-Borne Hazards, and 5.021, Agricultural Pesticide Protective
Equipment.
- There is an unknown contaminant. This is the most
frequently encountered danger in the work place. Detection of unknown
contaminants may require extensive and expensive analytical work. However,
it could be a simple and quick procedure.
- The contaminant level exceeds the ability of the respirator
to protect the wearer. The label on each respirator carton
or package contains specific information about maximum concentrations
and types of contaminants protected by the respirator. Study
this label carefully. As a rule, if the label does not specify
maximum concentrations, do not wear the respirator in atmospheres containing
more than five times (5X) 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.
- The respirator is not approved for the contaminant of concern.
Approval agencies are the National Institute for Occupational Safety
and Health (NIOSH) or the Mine Safety and Health Administration (MSHA).
Approved respirators will have a "TC" (tested and certified) number
on the label showing proper approval.
- The contaminant has a "skin" designation. Unless
other PPE is also used, contamination still results through dermal absorption,
even with an approved respirator. Examples are organophosphate pesticides,
such as malathion. Follow the pesticide label for the required PPE.
With those 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, re-evaluate your selection. Never use an
unapproved respirator; your life may depend on it.
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 to 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. 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. Select 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.
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. Weight gain or loss will require refitting.
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:
| Acid gases3 |
White |
| Organic vapors4 |
Black |
| Ammonia gas |
Green |
| Acid gases and organic vapors |
Yellow |
| Highly toxic particulate filter cartridge (HEPA)5 |
Purple |
2TLV is the time-weighted average concentration for a normal eight-hour workday and a 40-hour
workweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect.
3Acid gases include sulfur dioxide (SO2), chlorine gas (Cl2) and hydrochloric acid (HCl).
4Pesticides are classified as organic vapors.
5HEPA= high efficiency particulate attenuation.
Checklist of rules to protect you and your employees:
- Always inspect and test fit with new cartridges. Do not use a respirator that's been sitting
around since last season.
- Follow the test fit instructions.
- Clean the respirator daily according to manufacturer's instructions. To extend cartridge life,
store the respirator and cartridges in an air-tight bag.
- Store the respirator in a sealable plastic bag away from contaminants, not in a machine shop
or livestock confinement building. The cartridges in the respirator continue to absorb the
gases (e.g., exhaust fumes or pit gases) in a storage area until the charcoal has reached its
absorption capacity.
- Do not use respirators with beards or other facial hair that passes between the sealing flange
of the respirator and the face.
- Purchase air flow respirators from agricultural chemical and other dealers, safety supply
catalogs and hardware stores.
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