It's just a few days be­fore the Great­est Show on Earth, and since it has been a long sea­son, you've prob­a­bly had your fair share of al­co­hol. And while most of you may in­sist that you can "han­dle it", just bear in mind that drink­ing and dri­ving is a dead­ly com­bi­na­tion. One drink can re­duce your abil­i­ty to con­cen­trate and re­act to things that hap­pen sud­den­ly while you are dri­ving. The more al­co­hol in your blood, the more dif­fi­cul­ty you have judg­ing dis­tances and re­act­ing to sud­den haz­ards on the road. To make mat­ters even worse, your vi­sion may be­come blurred.

Fact sheet: blood al­co­hol con­cen­tra­tion (BAC)

The amount of al­co­hol in a per­son's body is mea­sured by the amount of the al­co­hol in blood. This is called the blood al­co­hol con­cen­tra­tion, or BAC. For the pur­pos­es of law en­force­ment, BAC is used to de­fine in­tox­i­ca­tion and pro­vides a mea­sure of im­pair­ment. BAC lev­els are af­fect­ed by many fac­tors, in­clud­ing:

• How fast you drink. Al­co­hol con­sumed quick­ly will re­sult in a high­er BAC than when con­sumed over a long pe­ri­od of time.

• Gen­der. Women gen­er­al­ly have less wa­ter and more body fat per pound of body weight than men. Al­co­hol does not go in­to fat cells as eas­i­ly as oth­er cells, so more al­co­hol re­mains in the blood of women.

• Body weight. The more you weigh, the more wa­ter is present in your body. This wa­ter di­lutes the al­co­hol and low­ers the BAC.

• Amount of food in your stom­ach. Ab­sorp­tion is slowed if you've had some­thing to eat.

With a BAC of 0.05, an in­di­vid­ual's vi­sion may al­ready be af­fect­ed in terms of sen­si­tiv­i­ty to bright­ness, the abil­i­ty to de­ter­mine colours, and depth and mo­tion per­cep­tion. The brain's abil­i­ty to per­form sim­ple mo­tor func­tions is di­min­ished. This means that a dri­ver's re­ac­tion time will be slow­er and re­spons­es will be less ac­cu­rate. The re­sult is de­grad­ed dri­ving per­for­mance and a sig­nif­i­cant in­crease in col­li­sion risk. The in­creased col­li­sion risk of dri­vers with a BAC from 0.05 to 0.08 (al­so known as the "warn range") is well doc­u­ment­ed. Dri­vers with a BAC above 0.05 but be­low the le­gal lim­it are 7.2 times more like­ly to be in a fa­tal col­li­sion than dri­vers with a ze­ro BAC.

How much can I drink be­fore I reach the 0.05 BAC lim­it?

The num­ber of drinks con­sumed is a poor mea­sure of BAC be­cause of the many fac­tors af­fect­ing your body's abil­i­ty to di­gest al­co­hol, such as weight, body fat, and how long ago and how much you ate. Fac­tors like tired­ness and your mood can al­so make a dif­fer­ence in how al­co­hol af­fects your dri­ving abil­i­ty. It is very dif­fi­cult to as­sess your own BAC or im­pair­ment. Small amounts of al­co­hol af­fect one's brain and the abil­i­ty to dri­ve. If you plan on drink­ing, plan to not dri­ve.

Drugs and Dri­ving

Around Car­ni­val time catch­ing colds and flus are not un­com­mon. Re­mem­ber, any drug that changes your mood, or the way you see and feel, will af­fect the way you dri­ve. This is not on­ly true for il­le­gal drugs. There are pre­scrip­tion drugs and some over-the-counter drugs that can al­so im­pair your dri­ving abil­i­ty.

Tips to re­mem­ber

• If you are plan­ning on drink­ing, plan not to dri­ve.

• Ask your doc­tor about side ef­fects if you use pre­scrip­tion med­ica­tion or get al­ler­gy shots.

• Read the in­for­ma­tion on the pack­age of any over-the-counter med­i­cine, in­clud­ing al­ler­gy and cold reme­dies.

• Drugs and al­co­hol to­geth­er can com­bine to im­pair your dri­ving even more dras­ti­cal­ly; ask your doc­tor or phar­ma­cist.

Re­mem­ber, fa­tigue and stress will al­so af­fect your abil­i­ty to dri­ve.