Consider the following accident scenario: Two workers were assigned to replace a water valve located in an underground concrete vault.

Consider the following accident scenario:

Two workers were assigned to replace a water valve located in an underground concrete vault. After removing the manhole cover, worker #1 climbed down the ladder into the vault. Worker #1 collapsed and became unconscious within seconds of reaching the bottom. Worker #2 went down the ladder to rescue worker #1 but was quickly overcome by the lack of oxygen. Both workers died at the bottom of the vault.

Discuss how you could apply a domino theory to investigate this accident. You may make additional assumptions about the scenario, as needed, for your discussion.