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OHSA Respirator Provisions
(U.S. Occupational Health and Safety
Administration)
You need different types of filters,
cartridges, and canisters depending on whether dusts, fumes, mists, vapors
or gases are present in your workplace and depending on the kinds and
concentrations of the substances present.
Respiratory hazards may be present in the
workplace whenever an atmosphere does not contain sufficient oxygen, or if
it contains chemical, biological, or radiological contaminants in sufficient
quantity to harm the health of employees. Respiratory hazards may be present
in the workplace in the following physical forms:
Dusts and fibers are solid particles that
are formed or generated from solid materials through mechanical processes
such as crushing, grinding, drilling, abrading or blasting. Examples are
lead, silica and asbestos.
Fumes are solid particles that are formed
when a metal or other solid vaporizes and the molecules condense (or
solidify) in cool air. Examples are metal fumes from smelting or welding.
Fumes also may be formed from processes such as plastic injection or
extrusion molding.
Mists are tiny droplets of liquid
suspended in the air. Examples are oil mist produced from lubricants used in
metal cutting operations, acid mists from electroplating, and paint spray
mist from spraying operations.
Gases are materials that exist as
individual molecules in the air at room temperature. Examples are welding
gases, such as acetylene and nitrogen, and carbon monoxide produced from
internal combustion engines.
Vapors are the gaseous form of substances
that are normally in the solid or liquid state at room temperature and
pressure. They are formed by evaporation.
Most solvents produce vapors. Examples
include toluene and methylene chloride.
Biological hazards include bacteria,
viruses, fungi, and other living organisms that are respirable and can cause
acute and chronic infections. Examples include Legionnaire’s Disease and
animal waste products (e.g., feces).
Types of Respirators
The major types of respirators include
air-purifying respirators and atmosphere supplying respirators. An
air-purifying respirator is a respirator with an air-purifying filter,
cartridge, or canister that removes specific air contaminants by passing
ambient air through the air-purifying element.
An atmosphere-supplying respirator
supplies the respirator user with breathing air from a source independent of
the ambient atmosphere, and includes SARs and SCBA units.
To determine the protection provided by a
respirator during use, a protection factor study should be undertaken. This
determination generally is accomplished by measuring the ratio of the
concentration of an airborne contaminant (e.g., hazardous substance) outside
the respirator (Co) to the concentration inside the respirator (Ci) (i.e.,
Co/Ci). Therefore, as the ratio between Co and Ci increases, the protection
factor increases, indicating an increase in the level of protection provided
to employees by the respirator.
The
four types of protection factor studies are:
Effective Protection Factor (EPF) study —
a study conducted in the workplace that measures the protection provided by
a properly selected, fit tested, and functioning respirator when used
intermittently for only some fraction of the total workplace exposure time
(i.e., sampling is conducted during periods when respirators are worn and
not worn). EPFs are not directly comparable to WPF values because the
determinations include both the time spent in contaminated atmospheres with
and without respiratory protection; therefore, EPFs usually underestimate
the protection afforded by a respirator that is used continuously in the
workplace.
Program Protection Factor (PPF) study
— a study that estimates the protection provided by a respirator within a
specific respirator program. Like the EPF, it is focused not only on the
respirator’s performance, but also the effectiveness of the complete
respirator program. PPFs are affected by all factors of the program,
including respirator selection and maintenance, user training and
motivation, work activities, and program administration.
Workplace Protection Factor (WPF) study
— a study, conducted under actual
conditions of use in the workplace, that measures the protection provided by
a properly selected, fit tested, and functioning respirator, when the
respirator is worn correctly and used as part of a comprehensive respirator
program that is in compliance with OSHA’s Respiratory Protection standard at
29 CFR 1910.134.
Measurements of Co and Ci are obtained
only while the respirator is being worn during performance of normal work
tasks (i.e., samples are not collected when the respirator is not being
worn). As the degree of protection afforded by the respirator increases, the
WPF increases.
Simulated Workplace Protection Factor (SWPF) study
— a study, conducted in a controlled laboratory setting and in which Co and
Ci sampling is performed while the respirator user performs a series of set
exercises. The laboratory setting is used to control many of the variables
found in workplace studies, while the exercises simulate the work activities
of respirator users. This type of study is designed to determine the optimum
performance of respirators by reducing the impact of sources of variability
through maintenance of tightly controlled study conditions.
Glossary of Terms Other terms users
should be familiar with include the following:
Canister or cartridge:
A container with a filter, sorbent, or catalyst, or combination of these
items that removes specific contaminants from the air passed through the
container.
Continuous flow respirator:
An atmosphere- supplying respirator that provides a continuous flow of
breathable air to the respirator facepiece.
Demand
respirator: An
atmospheresupplying respirator that admits breathing air to the facepiece
only when a negative pressure is created inside the facepiece by inhalation.
Dioctylphthalate (DOP):
An aerosolized agent used for quantitative fit testing.
Elastomeric: A
respirator facepiece made of a natural or synthetic elastic material such as
natural rubber, silicone, or EPDM rubber.
Filter
or air-purifying element:
A component used in respirators to remove solid or liquid aerosols from the
inspired air.
Filtering facepiece (or dust mask):
A negative pressure particulate respirator with a filter as an integral part
of the facepiece or with the entire facepiece composed of the filtering
medium.
Fit
factor: A
quantitative estimate of the fit of a particular respirator to a specific
individual that typically estimates the ratio of the concentration of a
substance in ambient air to its concentration inside the respirator when
worn.
Fit
test: The use of
a protocol to qualitatively or quantitatively evaluate the fit of a
respirator on an individual. Helmet: A rigid respiratory inlet covering that
also provides head protection against impact and penetration.
High
efficiency particulate air filter (HEPA):
A filter that is at least 99.97 percent efficient in removing monodisperse
particles of 0.3 micrometers in diameter. The equivalent NIOSH 42 CFR 84
particulate filters are the N100, R100, and P100 filters.
Hood:
A respiratory inlet covering that completely covers the head and neck and
may also cover portions of the shoulders and torso. Immediately dangerous to
life or health (IDLH): An atmosphere that poses an immediate threat to life,
would cause irreversible adverse health effects, or would impair an
individual’s ability to escape from a dangerous atmosphere.
Loose-fitting facepiece:
A respiratory inlet covering that is designed to form a partial seal with
the face.
Negative pressure respirator (tightfitting):
A respirator in which the air pressure inside the facepiece is negative
during inhalation with respect to the ambient air pressure outside the
respirator.
Permissible Exposure Limit (PEL):
An occupational exposure limit specified by OSHA. Positive pressure
respirator: A respirator in which the pressure inside the respiratory inlet
covering exceeds the ambient air pressure outside the respirator.
Powered
air-purifying respirator (PAPR):
An air-purifying respirator that uses a blower to force the ambient air
through air-purifying elements to the inlet covering.
Pressure demand respirator:
A positive pressure
atmosphere-supplying respirator that admits breathing air to the facepiece
when the positive pressure is reduced inside the facepiece by inhalation.
Qualitative fit test (QLFT):
A pass/fail fit test to assess the adequacy of respirator fit that relies on
the individual’s response to the test agent.
Quantitative fit test (QNFT):
An assessment of the adequacy of respirator fit by numerically measuring the
amount of leakage into the respirator.
Recommended Exposure Limit (REL):
An occupational exposure level recommended by NIOSH.
Respirator Decision Logic (RDL):
Respirator selection guidance developed by NIOSH that contains a set of
respirator protection factors.
Self-contained breathing apparatus (SCBA):
An atmosphere-supplying respirator for which the breathing air source is
designed to be carried by the user.
Supplied-air respirator (or airline) respirator (SAR):
An atmosphere-supplying respirator for which the source of breathing air is
not designed to be carried by the user.
Threshold Limit Value (TLV):
An occupational exposure level recommended by ACGIH. Tight-fitting facepiece:
A respiratory inlet covering that forms a complete seal with the face.
Assigned
Protection Factors
Mandatory Respirator Selection Provisions Added to Existing Standard
For a respiratory protection program to be
effective, the correct respirator must be chosen, and worn appropriately.
To improve the
selection process, OSHA has published “Assigned Protection Factors” (APF), a
new guidance document that provides employers with vital information for
selecting respirators for employees exposed to contaminants in the air.
OSHA revised its existing Respiratory
Protection standard (29 CFR 1910.134) in 2006 to add APFs and Maximum Use
Concentration (MUC) provisions. APF means the workplace level of respiratory
protection that a respirator or class of respirators is able to provide to
workers.
The higher the APF number (5 to 10,000),
the greater the level of protection provided to the user. APFs are used to
select the appropriate class of respirators that will provide the necessary
level of protection against airborne contaminants. Such exposures can come
from particles or a gas or vapor.
MUC represents the limit at which the
class of respirator is expected to provide protection. Whenever a hazard’s
exposure level exceeds MUC, employers should select a respirator with a
higher APF. MUC means the maximum atmospheric concentration of a hazardous
substance for which a worker can expect to be protected when wearing a
respirator.
“Proper respirator selection prevents
exposure to hazardous contaminants and is an important component of an
effective respiratory protection program,” said Deputy Assistant Secretary
of Labor for OSHA Donald G. Shalhoub. “This guidance document serves as
another useful resource for protecting the health and safety of workers at
risk for respiratory illnesses.”
APF and MUC are mandatory respirator
selection requirements that can only be used after respirators are properly
selected and are used in compliance with the entire standard. The
Respiratory Protection standard requires fit testing, medical evaluations,
specific training and proper respirator use. The standard applies to general
industry, construction, long-shoring, shipyard and marine terminal
workplaces.
The MUC usually can be determined
mathematically by multiplying the assigned protection factor specified for a
respirator by the permissible exposure limit (PEL), short-term exposure
limit, ceiling limit, peak limit, or any other exposure limit used for the
hazardous substance.
The MUC for respirators is calculated by
multiplying the APF for the respirator by the PEL. The MUC is the upper
limit at which the class of respirator is expected to provide protection.
Whenever the exposures approach the MUC, then the employer should select the
next higher class of respirators for the employees.
Employers must not apply MUCs to
conditions that are immediately dangerous to life or health (IDLH); instead,
they must use respirators listed for IDLH conditions in paragraph (d)(2) of
the standard.
When the calculated MUC exceeds the IDLH
level for a hazardous substance, or the performance limits of the cartridge
or canister, then employers must set the maximum MUC at that lower limit.
How to
use APFs and MUCs
Under the Respiratory Protection
standard, APFs and MUCs are used specifically in selecting proper equipment
under section (d)(3), which addresses the selection of respiratory
protection equipment for non-IDLH atmospheres.
In this provision, under (d)(3)(i),
employers must provide respirators that are adequate to protect employee
health and ensure compliance with all other OSHA requirements under routine,
and reasonably foreseeable, emergency situations.
Under paragraph (d)(3)(i)(A), employers
must select respirators according to APFs. Under paragraph (d)(3)(i)(B),
employers must select respirators after considering the MUCs in their
workplace under which respirators are to be used. Under paragraph
(d)(3)(ii), employers must select respirators (using APFs as well) that are
appropriate for the chemical state and physical form of the contaminant.
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