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664 HAZWOPER for General Site Workers V
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Visible Indicators of Potential IDLH and Other Dangerous Conditions

While off-site, the qualified person will look for indicators that give clues about the nature of the hazards on-site, including:

  • large containers or tanks that must be entered
  • enclosed spaces such as buildings or trenches that must be entered
  • potentially explosive or flammable situations (indicated by bulging drums, effervescence, gas generation, or instrument readings)
  • extremely hazardous materials (such as cyanide, phosgene, or radiation sources), visible vapor clouds
  • areas where biological indicators (such as dead animals or vegetation) are located

Knowledge Check Choose the best answer for the question.

1-4. Which is an indicator that gives clues about the nature of on-site hazards?