Contributors

Tuesday, July 15, 2014

It's Time...

Every year thousands of kids get the wrong dose of medicine in the United States. Some of them are made sicker, some of them don't get better or stay sick longer, and some of them die. Why?

The United States uses an arcane and outdated measurement system. The English system is used for some things, but the metric system for other things. Science and medicine use the metric system, the United States military uses the metric system, most manufactured products use the metric system, including cars, bicycles, computers, etc., but plumbing and carpentry supplies are still manufactured to English specifications. This means that Americans have to own two sets of tools, and are constantly wondering which set they need. Our speed limits and maps all still use English.

The same problem exists in medicine. The dosages for liquid medications are sometimes prescribed in milliliters, but most frequently in teaspoons or tablespoons. Pharmacists can mix up teaspoons and tablespoons because the abbreviations are so similar (tsp. and tbsp.) and physician's scribbles are often difficult to decipher. Even if it's written correctly, anyone who's ever done any baking knows how easy it is to mix up teaspoons and tablespoons, which can result in dangerously wrong dosages.

To make things worse, parents often use a regular teaspoon that you eat cereal with instead of an actual measuring teaspoon. They just eyeball half a teaspoon instead of finding an actual half-teaspoon measuring spoon. Because children have such low body mass, and some medicines are so powerful, an overdose can have serious consequences, resulting in injury and even death.

To fix this many professional associations are recommending all liquid medicines be administered in milliliters (mL). Whenever you get a prescription for liquid medicines you would get a small measurement cup with markings in mL. A study recently found that parents dosing in mL made far fewer mistakes.

Dealing with multiple measurement systems causes errors. The Mars Climate Orbiter was lost because one subcontractor provided data in pound force seconds instead of newton seconds. In the United States patient weights are recorded on scales that read in pounds, but dosages for medications are typically calculated in milliliters per kilogram of body weight, which means doctors have to convert your body weight into metric and then convert the calculated dose back into English.

None of this makes any sense. Nearly every product you buy in the store is marked in both English and metric, since manufacturers want to be able to export without having to repackage goods for different markets.

Even more idiotically, there are multiple English systems in common usage. Ships and aircraft still use "nautical miles," which are 800 feet longer than "statute miles." There are U.S. gallons and imperial gallons. There are regular feet and "survey feet." And then there's the profusion of different units: chains, rods, acres, fathoms, yards, fluid ounces, dry ounces, pints, quarts, cups, gallons, BTUs, blah, blah, blah.

We should just dump all that crap. Most everyone in the United States is already familiar with the metric system anyway: we buy cars with 2-liter engines, 9-millimeter pistols, and two-liter bottles of soda.

The metric system is so much easier to use. If you pick up a 16-millimeter wrench and it's just a little too big for the bolt you're tightening, the 15-millimeter wrench is the obvious choice. But if the 5/8" wrench is too big, do you pick up the 3/4", the 1/2", or the 9/16"?

If you want to increase a recipe by a quarter and you need 1 1/2 cups of sugar, and you can still remember how to multiply fractions from middle school, bully for you! But you wind up with 5/4 x 3/2 = 15/8 of a cup. What a pain to measure. You can convert to decimal to avoid fractions, but how do you measure 1.875 cups? With metric, 300 grams of sugar is easily converted: 300 x 1.25 = 375 grams. Things like flour are better measured by weight instead of volume anyway, because of settling. Adding linear measurements is just as much fun: how long is 12 3/4" plus 3 1/8" plus 2 5/16"? Wouldn't you rather add 12.75, 3.13 and 2.31?

"But what about football?" someone in the crowd yells. "We can't change yards to meters and ruin our glorious tradition! You can't have a first down at the 45.72 meter line!"

Amazingly, soccer has solved this problem: the field (or pitch, as the Brits are wont to say) is still measured in yards. For example, the centre circle is 10 yards from the centre spot and the rules provide a metric equivalent (9.15 meters). So, even if you drive 20 kilometers to a football game, you can still sit in your reserved seats on the 50-yard-line.

Sports like basketball and volleyball have updated some of the measurements. Internationally the basketball court is 28 x15 meters, but the rim is still 10 feet (3.05 m). The volleyball court is 10 m on a side (29' 6"), but the net is still 7' 11 5/8". That's 2.43 meters, in case you're wondering.

Because fractions are used in English measurements, it can be confusing to notate and interpret measurements on computers (like, for example, 7' 11 5/8"), making it easy for errors and misunderstandings to creep in. Plus, I've never had a calculator that adds fractions, but they all add metric just fine.

We should just bite the 9-mm bullet and switch to metric.