PRINCIPLES OF CONTROL

1
PRINCIPLES OF CONTROL

• ...a discussion of the strategies and methods
  available to achieve control of health hazards.

2
CONTROL ASSUMPTIONS

• All hazards can be controlled to some degree by
  some method.
• Alternative approaches are available.
• More than one approach may be needed.
• Cost-effectiveness varies with approach.
• A given approach may not completely control the
  hazard.

3
HIERARCHY OF CONTROL STRATEGIES

• PREVENTION (?)
• ENGINEERING
• ADMINISTRATIVE
• includes work practices
• PERSONAL PROTECTION

4
SITUATION NO. 1

• Design of a plan for assembly of metal cabinets
  included a need to join several pieces of metal
  together and welding was being considered.
• Traditional exposure control is based on
  ventilation and/or respirators.
• What are some prevention options for the IH?

5
CONTROL BEGINS _at_ DESIGN

• technologically more difficult to retrofit
• always more expensive after design
• industrial hygiene input to design
• design criteria must include consideration for
  worker safety
• Institute for Safety Through Design

6
IMPLEMENTING CONTROLS

• Identify the hazard.
• Define sources of exposure.
• Characterize worker involvement.
• Understand air flow patterns.
• Examine control options.
• Select/implement proper controls.
• Follow-up, test, maintain controls.

7
SITUATION NO. 2

• A plan view of a grain handling system in a food
  manufacturing plant
• Two workers in the building
• emissions, air movement, worker activities, etc.

8
ENGINEERING CONTROLS

• SUBSTITUTION
• ISOLATION
• ENCLOSURE
• PROCESS MODIFICATION
• VENTILATION
• DILUTION
• LOCAL EXHAUST

9
Industrial vs. Non-industrial Environments

• Industrial
• Mines, manufacturing facilities, plants
• Dusts from mines, solvents, heavy metals, vehicle
  emissions, grinding
• Non-industrial
• Stores, offices, warehouses
• Tobacco smoke, ozone, mold spores, formaldehyde,
  products from remodeling (adhesives, paints),
  cleaners

10
A word about contaminant form...

• particulates
• dusts
• fumes
• smoke
• fibers
• mists/fogs
• gases
• vapors

11
SUBSTITUTION

• generally applies to chemical hazards
• a hazardous material is replaced by one of less
  hazard
• some examples
• potential problems with this approach

12
ISOLATION/CONTAINMENT

• a barrier is placed between hazard and workers
• physical or distance
• some examples
• potential problems with this approach

13
PROCESS MODIFICATION

• equipment, or its use, is modified so as to
  reduce hazard
• some examples
• potential problems with this approach

14
GENERAL VENTILATION

• contaminant is diluted to acceptable level
• usually less effective than LEV
• not for settleable contaminants
• some examples

15
LOCAL EXHAUST

• contaminant is captured at or near point of
  release
• usually the most desirable approach
• can be used for toxic materials
• some examples