The **blood alcohol concentration (BAC)** is the amount of alcohol present in the blood after consuming alcoholic beverages. This concentration is measured in grams of alcohol per liter of blood. The maximum allowed amount of alcohol in the blood varies according to the type of driver and the time they have held their driving license.

- For **novice drivers**, that is, those who have obtained their driving license less than two years ago, the maximum allowed concentration is **0.3 grams per liter of blood**. This is because drivers with less experience are more vulnerable to the effects of alcohol and, therefore, a stricter limit is applied to ensure road safety.

- On the other hand, for drivers with more than two years of experience, the allowed concentration is higher, at **0.5 grams per liter of blood**.

Since in this case the driver has had their license for one and a half years, the lower limit of **0.3 grams per liter of blood** applies. This ensures that novice drivers maintain a blood alcohol level that minimizes the risk of accidents.