What safety precautions are recommended when using the Intoxilyzer 9000?

The recommended safety precautions when using the Intoxilyzer 9000 encompass proper calibration, routine maintenance, and hygiene practices, making this the correct answer. Proper calibration ensures that the device provides accurate BAC readings, which is crucial for legal and safety reasons. Routine maintenance helps to keep the device functioning correctly and minimizes the risk of errors that could stem from wear or malfunction over time.

Hygiene practices are particularly important given that the device collects breath samples from individuals. Ensuring that the mouthpiece is clean before each use helps prevent cross-contamination and maintains the integrity of the test results.

The other choices provided do not encompass the comprehensive safety practices required for the operation of the Intoxilyzer 9000. For example, calibration should not be limited to just when a new device is received; it should occur regularly to ensure ongoing accuracy. Discarding breath samples after use does not address the essential routine maintenance and hygiene practices necessary for proper operation. Lastly, while using the device in controlled environments can enhance accuracy and reliability, it is not a holistic approach to safety that includes all the other critical aspects mentioned.