Fact: Almost a third of car crashes involve driving after alcohol consumption.

We all know that drinking alcohol has an effect on various functions of our bodies, but most of us aren’t sure what effect the amount we drink actually has. While most people don’t immediately go straight to slurred speech and stumbling around from their first drink, the negative effects of alcohol on vision, coordination, attention span, reaction time and judgment are still there, however slight we perceive them to be. These negative effects only build as more alcohol is consumed.

While someone’s blood alcohol concentration (BAC) can vary based on numerous factors such as someone’s tolerance, number of drinks, how fast they’re consumed, weight and gender, one thing is clear — impairment starts from the first drink. The National Highway Traffic Safety Administration has detailed how alcohol affects the body by BAC level up to .15% for the typical person, along with how it affects one’s ability to drive.

Starting at just .02%, you start to lose your ability to use proper judgment, along with a warm sensation and your mood starts to change. Additionally, your body loses its ability to rapidly track moving objects and its ability to do two things at the same time.

As more alcohol is consumed and the body’s BAC rises to .05% (legal limit in Utah for a DWI charge), your behavior starts to become more exaggerated and you lose small muscle functions such as focusing your eyes and judgment also becomes more impaired. This also usually comes with a good feeling, lowered alertness and loss of inhibition.

When driving, one’s coordination and ability to track moving objects become reduced while steering gets more difficult and responses to emergency driving situations become slower.

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.08% BAC (Legal BAC limit in the U.S. and Canada, except for Utah)

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Classic signs of alcohol impairment become more apparent with loss of coordination for things such as balance, speech, vision and reaction time. It becomes more difficult to detect danger as judgment, self-control, reasoning and memory are also impaired.

For drivers, concentration is more difficult, short-term memory loss takes effect, the ability to control speed diminishes and your information processing capability for detecting traffic signs and signals is reduced. Visual search gets tougher, and perception becomes impaired.

This is also where drivers are legally considered drunk and driving is illegal.

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.10% BAC

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Reaction time and self-control are noticeably impacted here while speech is slurred, coordination is also poor and the thinking process slows. Drivers find it difficult to maintain lane position or brake appropriately as their ability slows even more.

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.15% BAC

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This is where the “sloppy drunk” territory starts to begin, with the body having much less muscle control than normal, as evidenced by stumbling, and one’s ability to balance takes a massive blow. For those not used to drinking, blackouts can also start here to go along with vomiting unless this level is reached slowly or one’s alcohol tolerance level is high enough. At this point, your impairment is considered severe when controlling a car, with attention to driving tasks and processing what you’re seeing and hearing becomes much slower.

While this column focuses on blood alcohol concentration, other intoxicants, such as prescription and over-the-counter drugs, legal and illegal, have similar effects. And these effects are magnified when combined with alcohol.