NIOSH 87-113: A Guide to Safety in Confined Spaces

Question 1

Most substances in a confined space should be considered hazardous. What are three possible sources for toxic substances in a confined space? (NIOSH, Page 6)

Answer 1

1) product stored in space
2) work being performed in space
3) areas adjacent to the space

Question 2

When testing a confined space for the presence of a hazardous atmosphere, what areas of the confined space must be tested? Why is this so? (NIOSH, Page 7)

Answer 2

Some gases and vapors are lighter than air while some are heavier than air that’s why it’s important to test all areas of a confined space to determine what gases are present.

NOTE: A related publication (NIOSH 80-106) states that “Entry into a confined space is prohibited until initial testing of the atmosphere has been done from the outside.”

Question 3

What must be done before workers enter a confined space that has been found to be oxygen deficient or containing toxic gases or vapors. (NIOSH, Page 7)

Answer 3

The space must be ventilated and re-tested before workers enter.

Question 4

What is meant by the term “isolation of a confined space”? What are some common ways that isolation of a confined space can be accomplished? (NIOSH, Page 9)

Answer 4

a) Isolation of a confined space is a process where the space is removed from service by:
b) locking out
c) blanking and bleeding
d) disconnecting
e) securing

Question 5

What three types of hazardous atmospheres can result from the lack of natural air movement in a confined space? (NIOSH, Page 4)

Answer 5

1) oxygen-deficient atmospheres
2) flammable atmospheres
3) toxic atmospheres