Final answer:
The statement is true; halide leak detectors should be used in well-ventilated areas due to the toxic phosgene gas produced when chlorinated hydrocarbons are heated.
Step-by-step explanation:
The statement is true. A halide leak detector should indeed be used in well-ventilated areas. When a halide leak detector is used on refrigerant gases, and a blue or green flame is observed, it is an indication of the production of phosgene gas, which is highly toxic. It is formed when chlorinated hydrocarbon compounds, such as carbon tetrachloride (CCl4), are subjected to high temperatures in the presence of flame, producing phosgene (COCl2). Utilizing a halide leak detector in well-ventilated areas is crucial for safety to avoid inhalation of phosgene and other toxic gases that may be produced during the detection process.