When collecting outside TEM samples, how far should they be kept from the decon unit?

• A. 25 feet
• B. 50 feet
• C. 75 feet
• D. 100 feet

Answer: (B)

Keeping a safe distance from the decon unit when collecting outside TEM samples helps prevent cross-contamination from the cleaning process and any plume or residues that might be produced during decontamination. Fifty feet provides a practical safety margin that accounts for typical air currents and the potential for aerosolized particles to travel beyond the immediate area, while still keeping sampling logistics manageable. A shorter distance, like twenty-five feet, could allow residual decon materials to reach the sample area, whereas larger gaps such as seventy-five or one hundred feet, though offering more clearance, are usually unnecessary in standard layouts and can hinder workflow without adding meaningful safety benefits.