Abstract: At 7:30 p.m. on July 2, 2021, Employee # 1, Employee #2, and Employee #3, were performing two maintenance tasks in the M2 crude rectification section on the ground and second levels at tower M2-T250 and vessel V-207. On July 2, 2021, during the night shift, three (3) gas monomer chemical operators were exposed to toxic fluorocarbons and other hazardous chemicals while performing the maintenance tasks at M2-T250 that resulted in delayed respiratory failure. The three employees were exposed to unknown and known acute toxic chemicals identified as expected to be in the process streams such as, but not limited to, Perfluorocyclobutane (C318), Perfluoroisobutene (PFiB), Octafluoroisomethylether (OIME), and/or Hydrogen Fluoride (HF) when returning T250 back to normal operations due to inadequate safe work practices and respiratory protection. On July 4 after Employee #1 and Employee #2 's shift ended, they had problems breathing that progressively worsened and they went separately to the hospital where they were admitted for respiratory failure. Employee #2 later died from respiratory failure. Then, Employee #3 worked his shift on July 3, and on July 4, the employee had trouble breathing that was worsening when he walked to his car. The employee was admitted for respiratory failure. The employee later died from respiratory failure.