Carbon monoxide (CO) is a by-product of reduction furnaces. It is reused as an energy source elsewhere in the complex, and extreme vigilance is required when it is present in the workplace. Each worker assigned to a risk area wears a dosimeter that measures and controls exposure to CO, alerting the worker when there is a possibility of overexposure. The Pac III dosimeter, which was specially designed for QIT, greatly improves control of CO exposure. Average exposure levels at QIT are now much lower than industry standards.