Final answer:
The legal Blood Alcohol Concentration (BAC) limit in Pennsylvania for operating a motor vehicle is 0.08% by volume.
Step-by-step explanation:
In Pennsylvania, the legal Blood Alcohol Concentration (BAC) limit for operating a motor vehicle is 0.08% by volume.
When the BAC reaches this level or higher, it is considered illegal and unsafe to operate a vehicle. At higher levels of BAC, acute intoxication, unconsciousness, and even death can occur.
To measure BAC, a portable device called a Breathalyzer is often used, which measures the ethanol concentration in a person's breath. This ethanol concentration is directly proportional to the blood alcohol level.