7.3 Introduction to occupational exposure limits

An 8 hour time-weighted average is used for:

• 1 Radiation dose
• 2 Long-term exposure limits
• 3 Peak noise only
• 4 Short-term limits

The purpose of an occupational exposure limit is to:

• 1 Replace the need for controls
• 2 Provide a benchmark for judging control
• 3 Measure noise
• 4 Ban substances

A limitation of exposure limits is that:

• 1 They guarantee safety
• 2 They apply to skin only
• 3 They do not allow for combined exposure to several substances
• 4 They are the same for all substances

A long-term exposure limit is normally averaged over:

• 1 1 minute
• 2 10 years
• 3 8 hours
• 4 1 week of rest

A short-term exposure limit usually relates to:

• 1 A year
• 2 A month
• 3 A period of about 15 minutes
• 4 A lifetime

TWA stands for:

• 1 Total work area
• 2 Toxic waste agent
• 3 Time-weighted average
• 4 Temporary working allowance

Why are time-weighted averages used?

• 1 They replace limits
• 2 The effect of many substances depends on the total dose over time
• 3 They make limits higher always
• 4 They are easier to remember

Occupational exposure limits are expressed as:

• 1 Lux
• 2 Airborne concentrations of a substance
• 3 Kilograms
• 4 Decibels

An exposure limit does not apply well to:

• 1 A cold day
• 2 A single, well known substance
• 3 A short task
• 4 Combined exposure to several substances

A limitation of exposure limits is that they:

• 1 Cover every substance
• 2 Include skin absorption always
• 3 Cannot be measured
• 4 Assume healthy adults

A measured level that is below the limit means that:

• 1 The substance is harmless
• 2 Controls can be removed
• 3 Exposure meets the standard but is not necessarily safe
• 4 No further action is needed ever

Exposure limits do not cover skin absorption unless:

• 1 The limit is high
• 2 The substance is a gas
• 3 They carry an indication that skin absorption is a route
• 4 The worker wears gloves

The purpose of an exposure limit is to:

• 1 Increase output
• 2 Ban all substances
• 3 Replace the SDS
• 4 Set a benchmark for judging whether controls are adequate

Measurements of airborne concentrations are compared with:

• 1 The number of workers
• 2 Recognised standards
• 3 The company turnover
• 4 The shift length

Why is a short-term exposure limit used as well as an 8 hour limit?

• 1 To control short peaks of high exposure
• 2 To make exposure measurement unnecessary
• 3 To apply only to biological agents
• 4 To replace the 8 hour limit