Final answer:
The legal limit for blood alcohol concentration (BAC) in the U.S and Canada is 0.08%. This threshold is considered the point of legal intoxication for the purposes of driving laws. The breathalyzer measures BAC through breath, and factors like age and health can affect individual metabolism rates.
Step-by-step explanation:
In the United States and Canada, the legal limit for blood alcohol concentration (BAC) is 0.08%. At this level, an individual is considered legally intoxicated and it is illegal to drive. The BAC is a measure of alcohol intoxication used for legal or medical purposes. A BAC of 0.08% means that there are 0.08 grams of alcohol per 100 milliliters of blood. Drinking beyond this limit increases the risk of harm, as higher BAC levels can lead to acute intoxication, unconsciousness, and even death at levels around 0.50%.
The breathalyzer is commonly used to estimate BAC through a breath sample. It is important to note that the ability to metabolize alcohol and the rate at which it affects the body can vary between individuals due to factors such as age, sex, and overall health. Nonetheless, the legal threshold is set at 0.08% across most jurisdictions to ensure safety on the roads.