Occupational Hygiene Control Part2...3 Occupational Hygiene – Control of Chemical Health Risks –...
Transcript of Occupational Hygiene Control Part2...3 Occupational Hygiene – Control of Chemical Health Risks –...
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Occupational Hygiene – Control of Chemical Health Risks – Part 2Frances Wright
Occupational Hygiene – Control of
Chemical Health Risks – Part 2
Frances Wright
Occupational Hygienist Wright Environmental Services
Module OSH10020
Part 1
Hierarchy of Control
Part 2
Ventilation and Respiratory Protective Equipment
Occupational Hygiene – Control of Chemical Health Risks
Identify Processes
& Workers
Evaluate the RiskControl the Risk
Document,
Communicate &
Review
Identify the Chemical Hazards
CHEMICAL
RISK ASSESSMENT
Hierarchy of Control
� Elimination
� Substitution
� Process changes
� Engineering controls
� Automation
� Containment
� Local Exhaust Ventilation
� General Area Ventilation
� Administrative controls
� Respiratory Protective Equipment
Least Preferred
Most preferred
Dilution
ventilation
Local exhaust
ventilation
Dilution Ventilation• Dilutes concentration in the general area
• USES:
• Operator is removed from source
• Low toxicity substances
• Low level concentrations
• Odours
• Improve indoor air quality
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Occupational Hygiene – Control of Chemical Health Risks – Part 2Frances Wright
Dilution Ventilation• ADVANTAGES:
• Less maintenance than LEV
• Lower costs
• Independent of operator
Dilution Ventilation• DISADVANTAGES:
• Does not completely remove contaminant
• Can spread the contaminant around workplace
• Make up air (heating/cooling)
Dilution Ventilation• DESIGN
• Move the contaminant away from worker
AIR EXTRACT AIR INSOURCE
Dilution Ventilation
Local Exhaust Ventilation� Removes the contaminant from the workplace
at the source
LEV - Components
• Hood – Contaminant to enter
• Ducting – Transports contaminant
• Air Cleaner – Cleans air
• Air Mover – Fan to move air
• Discharge Point – Safe emission point
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Occupational Hygiene – Control of Chemical Health Risks – Part 2Frances Wright
A Typical LEV SystemEnclosing
Capturing
Receiving
Source: HSE
The three basic types of LEV hood
Full Enclosure - Isolator/Glove Box Partial Enclosures - Fume Cupboard
Room Enclosures –Spray Booth Receiving Hoods - Circular Saw
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Occupational Hygiene – Control of Chemical Health Risks – Part 2Frances Wright
Capturing Hoods – Evaporation LEV DesignImportance of Enclosure
Increased Efficiency
LEV Design� Capture Velocity
� Face Velocity
� Transport Velocity
� Capture Zone
LEV DesignMaintenance and Testing
Smoke Test
Hot Wire Anemometer
Capture Zone
LEV DesignHood Placement — Capture Contaminant
LEV Design
Hood Placement – Move the contaminant from the
breathing zone
Direction of
air flow
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Occupational Hygiene – Control of Chemical Health Risks – Part 2Frances Wright
LEV Design
Hood placement – Move the
contaminant from the breathing
zone
LEV Design
LEV Design LEV Design
LEV Guidance� Heath and Safety Authority (Ireland)
� Due for publication in 2014
� Health and Safety Executive (UK)
� “Controlling airborne contaminants at work –
A Guide To Local Exhaust Ventilation”
Respiratory Protective Equipment � Air Purifying� Filters/Reduces the contamination
� Clean Air Supply� Provides uncontaminated air supply
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Occupational Hygiene – Control of Chemical Health Risks – Part 2Frances Wright
Air Purifying Respirators� Particulates
– Dusts, fumes, fibres, mists
� Gases and vapours
� Combination filters
Air Purifying Respirators� Non – powered
� Powered
Air Purifying RespiratorsNon powered
“Disposable” Half face piece Full face piece
Air Purifying RespiratorsPowered
Supplied Air RespiratorsClean Air Supply Via Air Line
Workplace Example Supplied Air Respirators - Air Line
Spray Painting - Isocyanates
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Occupational Hygiene – Control of Chemical Health Risks – Part 2Frances Wright
Workplace Example Supplied Air Respirators - SCBA
Self Contained Breathing Apparatus (SCBA)
Workplace Example Supplied Air Respirators - SCBA
Emergency/Rescue
Protection Provided Protection Factor (PF)
PF =
Ratio of the Concentration Outside RPE Versus Concentration Inside RPE
Concentration inside RPE must be below the Occupational Exposure Limit
Concentration Inside
Concentration Outside
Consider an asbestos atmosphere of 10 fibres / cc
Exposure limit 0.1 fibres / cc
Concentration inside mask
(PF10)
1.0 fibres / cc
Concentration inside mask
(PF 50)
0.2 fibres / cc
Concentration inside mask
(PF 100)
0.01fibres / cc
Rearrange the Formula : Concentration Inside = Concentration Outside
PF
Respiratory protection limitations� Not 100% efficient
� Contaminant concentration must be known
� Requires face fit and RPE programme
� Training essential
� Other staff not protected
� Communications difficulties
� Discomfort
� Always worn?
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Occupational Hygiene – Control of Chemical Health Risks – Part 2Frances Wright
Examples of uses of RPE
� Bottom of hierarchy of control
� Addition to other controls
� Short term or occasional use
� Maintenance
� Escape
Guidelines on Respiratory Protective Equipment
Dilution
ventilation
Local exhaust
ventilation
SummarySummary –
Respiratory Protective Equipment
� Air Purifying� Filters/Reduces the contamination
� Clean Air Supply� Provides uncontaminated air supply
Part 1
Hierarchy of Control
Part 2
Ventilation and Respiratory Protective Equipment
Occupational Hygiene – Control of Chemical Health Risks
Learning OutcomesHaving completed all of the learning activities associated with this
lecture, you should be able to:
� Apply the hierarchy of control measures to the management of
chemical hazards to health
� Give examples of control measures appropriate to different
health hazards
� Differentiate between local exhaust ventilation and dilution
ventilation
� Discuss the limitations on the use of respiratory protective
equipment, and provide the rationale for its use in different
circumstances
� Describe the different types of respiratory protective equipment
available.