Someone might start to report feeling in a good mood at what Blood alcohol concentration levels?

The answer is 0.001%

Explanation:

Different BAC levels result in different effects on an individual. In the United States, the legal BAC level for driving is 0.08%. At 0.019% BAC, an individual may start to feel in a good mood and uninhibited. However, it is important to remember that any BAC can affect an individual's behavior and judgment.