Exposure Limits

Question 1

What does TWA stand for and what does it measure?

Answer 1

Time Weighted Average; it sets a limit to the average exposure over a set time period, usually an eight-hour shift.

Question 2

What is the purpose of a Short Term Exposure Limit (STEL)?

Answer 2

It sets a limit based on a 15-minute exposure for gases that are immediately toxic.

Question 3

What happens if an individual is exposed to hazardous gases beyond TWA or STEL?

Answer 3

They will experience an adverse reaction.

Question 4

What is the IDLH value for Carbon Dioxide (CO2)?

Answer 4

40,000 ppm

Question 5

What is the TWA for Carbon Monoxide (CO)?

Answer 5

25 ppm

Question 6

Fill in the blank: The IDLH value for Hydrogen Sulphide (H2S) is _______.

Answer 6

100 ppm

Question 7

List the gases with their corresponding STEL values.

Answer 7

• Carbon Dioxide (CO2): 30,000 ppm
• Carbon Monoxide (CO): 100 ppm
• Hydrogen Sulphide (H2S): 15 ppm
• Nitrogen Dioxide (NO2): 5 ppm
• Sulphur Dioxide (SO2): 5 ppm
• Ammonia (NH3): 35 ppm

Question 8

What is the TWA for Nitrogen Dioxide (NO2)?

Answer 8

3 ppm

Question 9

True or False: The STEL for Ammonia (NH3) is lower than its TWA.

Answer 9

False

Question 10

What is the STEL for Sulphur Dioxide (SO2)?

Answer 10

5 ppm

Question 11

What does the acronym TWA represent in the context of exposure limits?

Answer 11

Time Weighted Average

Question 12

Fill in the blank: The exposure limit for Carbon Dioxide (CO2) at TWA is _______.

Answer 12

5,000 ppm

Question 13

What is the IDLH value for Nitrogen Dioxide (NO2)?

Answer 13

20 ppm

Question 14

What is the STEL for Carbon Dioxide (CO2)?

Answer 14

30,000 ppm