WMSU Lec4

CONTROL OF
HAZARDS
WMSU BS MECHANICAL ENGINEERING
1
Generalized Diagram of
Methods of Control
SOURCE AIR PATH RECEIVER
Environmental Safety
Hierarchy of Controls
• Refers to the total removal 1. Elimination • Eliminate human interaction in the process
of the hazards • Eliminate pinch points
• This involves replacing the 2. Substitution • Change in chemicals
hazard by one that presents
a lower risk
• A category of hazard 3. Engineering • Enclosures, containment, bunding, catch

control that uses controls pans, roofing over waste controls
physical/engineering • Drainage system, ventilation, Redesign of
• methods to eliminate or work area, insulation, Attenuation (
minimize the hazard mufflers), Wastewater treatment systems
• Scrubber systems, landfill
• A category of hazard control 4. Administrative • Safe work procedures
that uses administrative/ controls • Safety equipment inspections
• management involvement • Training
in order to minimize • Lockout
employee exposure to the
hazard
• Any device worn by a 5. Personal • Safety eyewear
worker to protect Protective • Hearing protection
• against hazards Equipment • Gloves
• Respirators
1. Engineering Control
Replacement/Substitution of materials
used
Modifications in the process and
equipment
Maintenance of equipment
Isolation
Wet methods
Ventilation
Isolation
Storage and handling
Isolation
Storage
and handling
Isolation
Isolation
Machine Guarding
2. Administrative Control
Rotation of job assignments
Adjusting work schedules
Maintenance and good housekeeping
Appropriate supervision
Emergency response training and education
Employee information and training
Visuals and signages
Maintenance and good housekeeping
Material Handling Equipment
Confined Space
Permit Required for Entry
THINK
SAFETY IS EVERYBODY’S JOB
3.Personal Protective
Equipment
17
AREAS OF PROTECTION
Head
Eye and Face
Hearing Body
Hand
Respiratory
Foot
Examples:
Dust/Gas Respirators
Safety
Goggles/Spectacles
Face Shields/Visor
Gloves
Protective
clothing/Aprons
Safety Shoes
Helmets
Earplugs/Earmuffs
HEAD PROTECTON
Provided if…
• Objects might fall from above
and strike employees on the head
• Employees might bump their heads against
fixed objects
• Employees work near exposed electrical
conductors
• Personnel at risk of hair entanglement shall
confine their hair or beard
HEAD Injury
HEAD PROTECTON
Bump Cap/Baseball Cap When head protection is
desired but not required,
Bump Caps reduce
exposure to lacerations
and abrasions caused by
minor bumps to the head.
Bump Caps are
appropriate ONLY for work
situations which do not
require ANSI compliant
head protection.
HEAD PROTECTON
Hard Hat Type of helmet predominantly
used in workplace
environments such as
industrial or construction sites
to protect the head from injury
due to falling objects, impact
with other objects, debris,
rain, and electric shock.
Suspension bands inside the
helmet spreads the helmet's
weight and the force of any
impact over the top of the
head.
EYE AND FACE PROTECTION
Provided when…
• Dust and other flying particles are present
• Molten metal, acids and caustic liquid
chemicals might splash
• Blood, and potentially infectious body fluids
might splash, spray, or splatter
• Intense light is created by welding arcs &
lasers
Safety spectacles
Goggles
Welding shield and glasses
Laser safety goggles
Face shields
• Safety spectacles -
made with safety
frames constructed of
metal and/or plastic and
are fitted with either
corrective or plain
impact-resistant lenses.
• Safety spectacles are intended to shield the wearer's
eyes from impact hazards such as flying fragments,
objects, large chips, and particles
• Goggles - protect eyes,

eye sockets, and the
facial area immediately
surrounding the eyes
from impact, dust, and
splashes.
• Flying Objects- Chipping, drilling, scaling,

grinding, polishing, buffing,
• Flying particles, dust, wind, etc,
• Heat, sparks and splash from molten materials
• Welding shields. -
constructed of vulcanized
fiber or fiberglass and
fitted with a filtered lens,
these protective devices
are designed for the
specific hazards
associated with welding.
• Laser safety goggles -

provide a range of
protection against the
intense concentrations of
light produced by lasers.
• Face shields -
transparent sheets of
plastic extend from
the brow to below the
chin across the entire
width of the
employee’s head.
HEARING PROTECTON
Provided when…
• Continuous noise that is above the set
Threshold Limit Value (TLV) limit is
present
• Employee needs to be exposed to
noise for prolonged periods (more than
8 hours)
• Intermittent loud noise is common
NOISE IS TOO MUCH WHEN…
• It is difficult to hear after leaving an

area
• You begin to hear ringing sounds after
exposure
HEARING
• “As a rule, if you can’t

hear another person
talking in a normal voice
from three feet away, the
area may require hearing
protection.”
EXAMPLES OF DECIBEL LEVELS
APPROX. EXAM
DECIBEL LEVEL PLE
0 The quietest sound you can hear
20 Whisper, quite library
65 Normal conversation, typewriter
90 Lawnmower, shop tools
110 Chainsaw, pneumatic drill
115 Loud rock concert, auto horn
140 Jet engine, gun fire
Maximum allowed noise with hearing protector

HEARING PROTECTION
For unprotected ears, the allowed exposure time decreases by one-

half hour for each 5 dB increase in the average noise level
DURATION PER DAY SOUND LEVEL, dB
8 90
6 92
4 95
3 97
2 100
1.5 102
1 105
0.5 110
0.25 or less 115
HEARING PROTECTION
• Effects…
• Communication is difficult
(all sound is muffled)
• Poor concentration
• Fatigue
• High blood pressure
• Sleeping problems
• Anxiety/Stress
• Accidents
Disposable, single-use earplugs
TYPES OF HEARING PROTECTIVE

EQUIPMENT
Reusable earplugs
Pre-formed, molded earplugs
Earmuffs
RESPIRATORY PROTECTON
Provided when…
• Dusts, mists, fumes are

generated/present
• Harmful gases and vapors are inhaled
• Operations require spray painting
RESPIRATORY PROTECTION
CLASSES OF RESPIRATOR
• 1.0 Air Purifying Respirators ( APRS)
• 2.0 Supplied- Air Respirator (SARS)

AIR PURIFYING RESPIRATORS
Air Purifying Respirators (APRs)
• Can remove contaminants in the air

that you breathe by filtering out
particulates (e.g., dusts, metal
fumes, mists, etc.)
• Absorbing gases or vapors on
absorbent (adsorbing material) in a
cartridge or canister.
AIR PURIFYING RESPIRATORS
Available in several forms:
• Mouth bit respirator (fits in
the mouth and comes with a
nose clip to hold nostrils
closed - for escape
purposes only)
• Quarter-mask (covering the
nose and mouth)
• Half-face mask (covering
the face from the nose to
below the chin), sample
N95
• Full face piece (covering the
face from above the eyes to
below the chin).
RESPIRATORY EQUIPMENT
DISPOSABLE, SINGLE USE RESPIRATORS
N95 respirators
• Most common and basic form of

disposable respirators.
• Filtration efficiency of at least 95%
against solid and liquid particles that
do not contain oil.
• Designed to filter out particulate
matter only and are meant to be
discarded after a single use.
• Commonly used by health care
workers, researchers, animal care
staff, and the skilled trades.
RESPIRATORY EQUIPMENT
DISPOSABLE, SINGLE USE RESPIRATORS
N95 LIMITATIONS
• N95 respirators do not typically
provide chemical protection.
• Facial hair between the sealing
surface of the respirator and the
face will decrease the respirators
effectiveness.
• N95 respirators cannot be used for
protection against asbestos, lead,
and silica hazards.
• N95 respirators should not be used
when contaminant concentrations
exceed 10 times the OSHA
Permissible Exposure Limit (PEL).
Supplied- Air Respirator

(SARS)
• Supply clean air from a
compressed air tank or
through an air line.
Example of these classes of

respirators include:
Supplied-air respirators (SARs):

• Self-contained breathing
apparatus (SCBA),
• Airline supplied-air respirators,
• Protective suits that totally
encapsulate the wearer's body
and incorporate a life-support
system
BODY PROTECTON
Protect against…
 Intense heat
 Splashes of hot metals and other hot liquids
 Impact from tools, machinery, and materials
 Cuts and electrical and abrasion

BODY PROTECTON
Protect against…
 Hazardous chemicals
 Contact with potentially infectious materials,
e.g. blood
 Radiation
 Hazards and other hazards with the potential

to cause injury to the arms, legs or body.
REQUIREMENTS
Do not wear draped or

loose-fitting clothing of
any kind around moving
equipment.
Wear high visibility
clothing or vests if the
site Traffic Route risk
assessment has
identified a potential for
collisions between
pedestrians and vehicles
TYPES OF BODY PROTECTION
Vests and Jackets

Aprons
Coveralls
Surgical gowns
Full body suits
HAND PROTECTON
Provided to protect against…
• Burns • Punctures
• Bruises • Fractures
• Abrasions • Amputation
• Cuts • Chemical exposure
HAND PROTECTON
Provided to protect against…
• Pointed/sharp objects
• Objects with extreme temperature
• Corrosive/ toxic chemical
Hand Injury
FOOT PROTECTON
Protect against…
 Intense heat
 Splashes of hot metals and other hot liquids
 Impact from tools, machinery, and materials
 Cuts and electrical and abrasion

FOOT PROTECTON
Protect against…
 Hazardous chemicals
 Contact with potentially infectious materials,
e.g. blood
 Radiation
 Hazards and other hazards with the potential

to cause injury to the arms, legs or body.
FOOT Injury
Control techniques that depend upon
positive safety & health culture
Good housekeeping / Personal Hygiene
Employee training/education
Proper job procedures / instruction
Job observation
Rule compliance
Protective equipment compliance
Group communications
Effectiveness of Controls
The types of control vary in their effectiveness
according to the control hierarchy:
Elimination Most Effective

Substitution
Engineering
Administrative
PPE Least Effective
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CONTROL OF

• A category of hazard 3. Engineering • Enclosures, containment, bunding, catch

Storage and handling

Material Handling Equipment

• Goggles - protect eyes,

• Flying Objects- Chipping, drilling, scaling,

• Laser safety goggles -

• It is difficult to hear after leaving an

• “As a rule, if you can’t

Maximum allowed noise with hearing protector

For unprotected ears, the allowed exposure time decreases by one-

TYPES OF HEARING PROTECTIVE

Pre-formed, molded earplugs

• Dusts, mists, fumes are

• 1.0 Air Purifying Respirators ( APRS)

• 2.0 Supplied- Air Respirator (SARS)

Air Purifying Respirators (APRs)

• Can remove contaminants in the air

• Most common and basic form of

Supplied- Air Respirator

Example of these classes of

Supplied-air respirators (SARs):

 Impact from tools, machinery, and materials

 Cuts and electrical and abrasion

 Hazards and other hazards with the potential

Do not wear draped or

Vests and Jackets

Provided to protect against…

Provided to protect against…

 Impact from tools, machinery, and materials

 Cuts and electrical and abrasion

 Hazards and other hazards with the potential

Proper job procedures / instruction

Protective equipment compliance

Elimination Most Effective

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