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How BAC Level Affects Your Driving


Elevated blood alcohol levels affect a person’s motor skills.

Have you ever noticed a police officer asking a driver to walk a straight line? Usually this happens when the police suspects a driver to be under the influence of alcohol.  For this reason, some drivers are pulled over to submit to a breathalyser test to find out if their blood alcohol content (BAC) is within permissible limits. An elevated blood alcohol level affects a person’s motor skills and different BAC levels have different effects on the human body.

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How Is Alcohol Level in the Body Measured?

A driver’s BAC is measured using a breathalyzer. BAC is the measurement of the amount of alcohol on a person’s breath or in one’s bloodstream. The higher the BAC, the more alcohol a person has consumed and the more intoxicated he or she becomes. The BAC test measures alcohol content in grams per 100 ml of a person’s blood or 210 liters of a person’s breath. The legal limit of BAC is .08. (Learn more – Who Is Liable in Drunk Driving Accidents?)

How Blood Alcohol Content Affects a Person

BAC is probably the most reliable way to estimate a person’s level of intoxication. However, a person’s intoxication level can also be affected by other factors such as their gender, weight, height, genetics or effects of other drugs or medications. Here is how the body responds to different BAC levels.

  1. BAC 0.020-0.039% – The person becomes less shy than usual and may feel mild euphoria and relaxation. Some may even experience mild lightheadedness.
  2. BAC 0.040-0.059% – The person starts experiencing all previously mentioned effects more intensely. Their caution and judgement are reduced and reasoning and memory may also begin to decline.
  3. BAC 0.06-0.099% – The physical effects of alcohol become more intense, and the person may experience some loss of balance and may begin to lose some motor function. Even the vision and speech becomes impaired. The person may feel a strong sense of euphoria, and memory and reasoning decline further.
  4. BAC 0.100-0.129% – Speech becomes slurred and motor functions become significantly impaired. Judgement deteriorates, vision blurs, reaction time is lowered, and peripheral vision is reduced. There is also some hearing loss.
  5. BAC 0.130-0.159% – The driver no longer feels euphoria and starts experiencing dysphoria or a feeling of being unwell. The person has difficulty walking and speaking properly.
  6. BAC 0.160-0.199% – The person starts experiencing feeling of being unwell and nausea.
  7. BAC 0.200-0.249% – The person becomes completely unaware and confused. He or she may have difficulty moving without help. Nausea and dysphoria become intense and the person may vomit or blackout.
  8. BAC 0.250-0.399% – This stage is referred to as alcohol poisoning and the person may become unconscious.
  9. BAC 0.40% and up – At this stage, there is a high risk of respiratory arrest and the person may enter a coma.

Injured by a Drunk Driver

If you have been injured in an accident caused by drunk driving, consult with a St. Louis accident attorney. Call The Hoffmann Law Firm, L.L.C. at (314) 361-4242.

Updated: March 16, 2018