Monoxide Thumbs a Ride (Mar, 1947)

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Monoxide Thumbs a Ride

Drowsy while driving? Make sure carbon monoxide isn’t poisoning you at the wheel. A checkup may save a life.

CARBON monoxide is a hitchhiker. We all know that this odorless gas, generated by an automobile at the rate of about a cubic foot a minute, will quickly turn a closed garage into a death chamber, but we are apt to overlook the fact that it rides along each time we drive out on the highway. Its handiwork shows up in traffic accident news more frequently than most persons “realize. The police* reports may say that the driver “apparently fell asleep,” or perhaps a big question mark appears in the space where the cause of the accident should be recorded, since no one remains alive to tell about it. Some of these accidents, it is true, result from lack of sleep or just plain weariness after long hours of driving, but there seems to be no doubt that a good percentage occur when carbon monoxide, stealing a ride in the car, dulls the senses of the driver.

As an agent of death, carbon monoxide works by combining with the red corpuscles, preventing the blood from carrying oxygen throughout your body. A little goes a long way. Just two parts in 10,000 of air are enough to impair perceptions; and not much higher concentrations, breathed for a sufficient time, can prove fatal. When a car engine is operated in a closed garage, the air becomes dangerous to breathe within three minutes. Safety education has made most people aware of this, but comparatively few realize that there are equally important precautions that should be taken to minimize the danger of carbon monoxide out on the highway.

Tests conducted in Connecticut by the State Health Department and the Travelers Insurance Company underline the need for such precautions. Traces of carbon monoxide were found in nearly 50 per cent of a group of cars checked at random along the highway, and in more than 10 percent there were dangerous concentrations—enough to dull the senses, and possibly produce unconsciousness.

Concentrations of carbon monoxide below about 3.5 parts in 10,000 are not immediately dangerous, but if you are exposed long enough this amount will produce headache, mental dullness, and a sense of physical weariness. At 2 parts in 10,000, these primary symptoms generally occur in about two hours. Such symptoms, usually disregarded, are often the cause of inefficient driving and accidents.

Hence, if you ever develop a feeling of unreality while driving and the traffic and city street or countryside seem like something seen in a dream, it is high time that you open the car windows wide and pull up and park immediately until you again feel normal. Also, be wary of a headache that develops while you are driving.

If you suspect that an unsafe percentage of carbon monoxide is contaminating the interior of your car, you can make a test with the detector ampoules manufactured by the Mine Safety Appliances Company, of Pittsburgh. Although devised for the detection of dangerous carbon monoxide con-concentrations in manhole entrances, the ampoules are now used by garages, chemical plants, and other industries for the same purpose. They cost $1.25 for 10 ampoules.

Smaller than a cigarette, one of these ampoules will detect the presence of monoxide in air in concentrations as low as 2 or 3 parts in 10,000. They consist essentially of palladium chloride in an acetone-water (nonfreezing) solution, sealed in a glass tube surrounded by cotton.

In use, the ampoule is crushed between the fingers, allowing the solution to saturate the cotton. The ampoule is then left for 10 minutes in a place where carbon monoxide is suspected. Originally, the crushed ampoule is yellow. If monoxide is present, metallic palladium will darken the cotton, the depth of discoloration (running from a light gray to a grayish black) depending on the concentration of the gas. The concentration then can be determined by comparing the color of the ampoule after 10 minutes with the scale of colors on a chart furnished with the set. In a car you might place the crushed ampoule on top of the front ,seat, or better still,, hang it by a cord from the roof.

Contamination of the interior of a moving car may result either from the exhaust gases of your own car or those close ahead. A leaking exhaust system or a rusty or battered muffler often will allow the deadly gas to seep through cracks in the floor or doors. In some cars exhaust gases, instead of flowing away to the rear, actually move along with it because of the turbulent flow of air immediately behind, and monoxide-laden eddy currents may whip into the open windows—looking for a victim. If all of these sources of contamination joined forces, as easily they might, the cap could soon become a rolling death trap. Since carbon monoxide is a product of poor combustion, proper adjustment of the engine is an important factor in reducing the hazard. Experiments by the U. S. Bureau of Mines have shown that the proportion of this gas in automobile exhausts ranges from 1 to 13.72 percent and that the amounts vary widely at high and low speeds and with good and poor carburetion. As combustion efficiency increases, the monoxide content of the exhaust naturally decreases. The percentage may be as high as 13 from a poorly adjusted motor running at 50 percent efficiency. When the car has been tuned up to run at 80 percent efficiency, the monoxide content drops to 4 percent.

These percentages sometimes are put to use in reverse. Some garages have equipment to determine the monoxide content of a car exhaust. From this, it is possible to estimate the efficiency of the engine.

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