Among the most common ways of getting to work each morning, riding a motorcycle is the most likely to result in a traffic fatality. Motorcycles are 29 times more deadly per passenger-mile than cars, according to Ian Savage, who studies the economics and safety of transportation at Northwestern University in Evanston, Ill.

Per mile, taking a train is roughly 17 times safer than a car; buses are 67 times safer, which makes busing approximately 1,930 times safer than riding a motorcycle to work.

Even safer, but probably neither practical nor cost-effective, are commercial airlines, which are 3,000 times safer than motorcycles and 100 times safer per passenger-mile than cars.

Of course, walking is good, too. And better for you.

Remember what Steven Wright once said: “Anywhere is walking distance if you’ve got the time.”

Resolution Solution

We’re a week into the new year, and maybe all of those well-intentioned resolutions have fallen by the wayside. Try to keep this one: Wash your hands. Regularly. Routinely. Even a quick hand wash with just water and no soap can remove 90 percent of bacteria added to hands. Washing for 20 seconds with soap removes about 99 percent, on average.

In 2008, UNICEF estimated effective hand-washing could prevent up to 1.4 million deaths per year worldwide. The average American gets two to three colds per year (children get even more). Studies have shown that regular hand-washing can reduce that incidence by 20 percent.

Get Me That, Stat!

Sixty-four percent of Americans drink some form of coffee daily. When you throw in other caffeinated beverages — most types of tea, sodas — an estimated 90 percent of Americans get a caffeine rush every day.

Caffeine is addictive but relatively safe: You would need to drink 50 to 100 cups of coffee to reach a lethal dose.

Mark Your Calendar

January is National Awareness Month for Cervical Health and Glaucoma. It’s also National Birth Defects Prevention Month and Radon Action Month.

Radon is a naturally occurring radioactive gas that can cause lung cancer. You can’t see or smell it; only testing can determine the level of exposure, which is measured by assessing homes and levels of radon found in surrounding soil.

Doc Talk

Popliteal fossa: The posterior of the knee, otherwise known as the knee pit where your leg bends.

Mania of the Week

Enosimania: Pathological belief that one has sinned

Life in Big Macs

One hour of chopping wood energetically burns 1,156 calories (based on a 150-pound person) or the equivalent of 1.6 Big Macs.

Never Say ‘Diet’

The Major League Eating record for bologna is 2.76 pounds in six minutes, held by Don Lerman of Levittown, N.Y. — an eat of strength, no matter how you slice it.

Observation

“I like long walks, especially when they’re taken by people who annoy me.” — Comedian Fred Allen (1894-1956)

Medical History

This week in 1844, the first dental anesthetic was used by Dr. John M. Riggs for a tooth extraction on Dr. Horace Wells.

The previous day, Wells had attended a demonstration of the effects of inhaling nitrous oxide gas by a traveling lecturer, Gardner Quincy Colton. At the demonstration, Wells noticed that a man intoxicated by the “laughing gas” suffered a laceration to his leg but claimed to feel no pain.

Wells arranged for Colton to administer nitrous oxide to himself, while one of Wells’ associates successfully extracted one of his teeth.

Ig Nobel Apprised

The Ig Nobel Prizes celebrate achievements that make people laugh and then think — a look at real science that’s hard to take seriously and even harder to ignore.

In 2016, the Ig Nobel Prize in Perception went to a pair of Japanese researchers for their investigations of whether things look different when you bend over and view them between your legs. They concluded that when you view the world with your head upside down between your legs, perceived size and distance of objects are, in fact, affected.

Presumably, you also get dizzy and fall down a lot.

Sum Body

The vagus nerve runs from your brain to your visceral organs, overseeing a number of crucial functions. Here are six:

1. It regulates the inflammatory response.

2. It’s involved in making memories.

3. It helps you breathe.

4. It initiates relaxation.

5. It translates messages between gut and brain.

6. It is the most common cause of fainting, due to overstimulation.

Med School

Q: What percentage of your body weight is made up by blood?
a) 3 percent
b) 8 percent
c) 15 percent
d) 24 percent

A: 8 percent, or about 5.3 quarts.

Curtain Calls

Qin Shi Huang, the first emperor of China, whose artifacts and treasures include the famed Terracotta Army, died after ingesting several pills of mercury, which he believed would grant him eternal life.

— Scott LaFee is a staff writer at UC San Diego Health and the former chief science writer at The San Diego Union-Tribune, where he covered science, medicine and technology. Click here to read previous columns. The opinions expressed are his own.