Breath analyzers

I’ve never really been sure why New Year’s Eve is considered a good time to have a wild party. Are we celebrating the fact that 1996 is finally over (was it really that bad a year?) or trying not to think about what 1997 will hold?

Whatever, December 31 is a day known for parties, and hence for the consumption of alcohol. Apparently this isn’t a recent phenomenon, because it was on December 31, 1938, that another New Year’s Eve tradition was launched. That was the day when police in Indianapolis began using the world’s first roadside breath analyzer, the “Drunkometer,” invented by Dr. Rolla N. Harger, chair of the Department of Biochemistry at the Indiana University School of Medicine. Weaving-over-the-white-line revelers that night were in for a surprise.

Drinking and driving are a police matter because of the effects alcohol has on the human body, to whit:

Alcohol is easily absorbed into the bloodstream through the walls of the small intestine. How quickly it is absorbed determines how quickly its effects are felt. (Drinking while eating is less intoxicating than drinking on an empty stomach, because the fat and protein in the foods in the stomach delay alcohol absorption.)

The body immediately goes to work metabolizing alcohol. A small amount is processed by the kidneys and excreted in the urine, and a small amount is processed through the lungs and exhaled in the breath (which is why a breath test can determined blood alcohol concentration), but the bulk of it is metabolized by the liver, at a rate of about three fourths of an ounce to one ounce of whisky an hour (or about half a glass of wine or beer an hour). Most people drink more rapidly than that, so their blood alcohol concentration rises.

At .08 percent, in Saskatchewan, you’re legally intoxicated and cannot drive a motor vehicle. At 0.2 percent (obtained by drinking about 10 ounces of whiskey), a drinker has trouble controlling his emotions and may burst into laughter or tears. He also has trouble controlling his legs and will want to lie down.

At 0.3 percent (attainable by rapidly drinking a pint of whiskey), the drinker will have trouble understanding what’s being said and may pass out. From 0.35 to 0.5 percent, the part of the brain that controls breathing and heart action may be affected, and above 0.5 percent can be fatal.

The only way to determine the level of alcohol in a driver’s bloodstream until the breath analyzer came along was through blood or urine tests, which were time-consuming and expensive and, while they could be used to prove someone was drunk at the time of an accident, didn’t give police any tools for getting drunk drivers off the road before they had an accident.

Dr. Harger’s Drunkometer gave police that tool. At the same time, Dr. Glenn C. Forrester of St. Louis, Missouri, was working on a similar device, which he called the Intoximeter; after the Second World War, Michigan instituted the first statewide breath-testing program using the Intoximeter, and Dr. Forrester founded a company called Intoximeters, Inc. By the late 1950s, Intoximeters had introduced an improved product, called the Breathalyzer–and it’s that name that the public associates with roadside tests to this day, no matter what the brand name of the device actually being used.

The early breath-testing devices required the person being tested to blow into a balloon (to regulate the size of the breath sample). The exhaled breath in the balloon was then passed over chemicals that changed color in the presence of alcohol. The extent of the color change, precisely measured by photoelectric cells, revealed the amount of alcohol in the sample.

These devices, while generally accurate, could produce false results (using a mouthwash containing alcohol, for instance, could indicate you’d been drinking when you hadn’t), so the search continued for better technology.

By the mid-1980s, chemical-based devices gave way to devices that use infrared light to test for alcohol in breath samples. In an infrared breath-tester, a narrow band of infrared light, of a frequency that is absorbed by alcohol, is passed through one side of a breath sample. How much of this light makes it to the other side of the sample without being absorbed tells you very precisely the concentration of alcohol in the sample.

These devices, while more accurate and easier and faster to use than chemical-based breath testers, have their own problems: they’re expensive and they contain several mechanical components, which means they’re subject to break-downs.

As a result, researchers are still trying to come up with better ways to test for alcohol consumption. One new technology is electrochemical cells.

Fuel cells have been known since the early 1800s. In a fuel cell, two electrodes are immersed in an electrolyte–a substance that conducts electricity. Fuel of some sort–typically hydrogen–is provided to one electrode, and oxygen to the other. The result is a flow of electricity between the electrodes.

In a breath-tester that uses electrochemical cells, the alcohol in the breath becomes the fuel for the fuel cell. The higher the concentration of alcohol in the breath, the more electricity is generated, so all you have to do is measure the strength of the current being generated to determine the concentration of alcohol in the breath sample.

Another new (and Canadian-invented) technology doesn’t rely on a breath sample at all. The “Eyealyzer,” developed by Gwynne Giles, a pharmacologist at the University of Toronto, measures the concentration of alcohol in eye fluids.

This New Year’s Eve, why not drink a toast in honor of Dr. Hargar and all the scientists who continue to work on better ways to identify impaired drivers so they can be safely removed from the road?

Then take a taxi home.

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