To determine the **blood alcohol level** of a driver, a **urine test** can be conducted, but this must be carried out **only in a health center**. This is because, although initial tests to detect alcohol are conducted using portable devices at the scene, such as a breathalyzer, a more detailed and accurate analysis, like a urine test, requires a controlled and appropriate environment, such as that of a health center.

- **Initial tests**: Traffic officers use portable devices to measure the alcohol in the driver's breath. If the result is positive or there are obvious signs of consumption, a more precise test can be requested.

- **Analysis in a health center**: If the driver disagrees with the initial results or a more detailed confirmation is required, a urine test can be conducted in a health center. This procedure ensures the accuracy and validity of the results.

Therefore, the correct answer is that the urine test to determine the blood alcohol level is conducted **only in a health center**.