Abstract: At 1:00 p.m. on May 10, 2019, Employee #1 and his employer, a plumbing contractor, were working in the bathroom of a single-family residence. There was no ventilation. The employer was cutting rebar with a gas-powered HILTI DSH 700 cut-off saw. Employee #1 was bent down near the vents of the saw and spraying water at the point of operation. After approximately 45 minutes to an hour, the employee began to feel dizziness and vertigo from exposure to carbon monoxide fumes from the saw. Emergency services were called and arrived. The employee felt better after sitting in fresh air, and he refused treatment or transport.