Common Knowledge Shifts

[Xiaou2]

In a recent thread, I mentioned that when running, you should land on the ball of the foot, rather than the smash-the-heel method.  I was made aware of this sometime within the last 10yrs...  but I was told that was ancient knowledge.

 Anyways, Its made me curious to know of other shifts in common knowledge that have happened, but have not made it well into the publics awareness.

 For example, and the only few I can think of off-hand:

 1) Tilting the head back when you have a nose bleed.
 
      Instead, tilt it forwards, and keep pressure on it for a while.  Tilting back, causes you to swallow a lot of blood, or possibly get blood in the lungs... which isnt fun nor good.  It also seems to slows the clotting time down.

 2) Coughing or even sneezing into one hands.

     Ive seen this so often... and its always surprising.   If you cough into your hand, you cover your hand in germs.  Then, when you go to touch something... like a doorknob, faucet, etc.. you spread the stuff all over.

 Instead, cough into your shoulder.

 3) Holding a sneeze back
 
 If you have to sneeze, dont hold back.  It has potential to create a lot of serious problems:

 From yahoo:

For example, you can create a prolonged "ringing" sensation, or affect your hearing, which may or may not be temporary. There's also a chance you burst an eardrum. You can actually tear blood vessels and muscles within the head. A sinus hemorrhage is also possible, and it's reported that more than a few older people have actually sustained brain injury and possible death just out of fear of committing a social faux pas like a violent sneeze.

There's more danger possible as well. People have not only accidentally severely bitten their tongues during such an episode, they've severed parts of their tongues as well. Just because of the bacteria and organisms present in even the cleanest mouths can make the simple act of biting a chunk out of an inner cheek turn into a long recovery that must be watched carefully for infection.

More than a few have broken teeth by the force with which your upper and lower jaw can snap shut in the process. Even ruptures within the throat may occur or a esophagus can be damaged.

Then there is the issue of a relatively rare yet still possible effect of a repressed sneeze or anything else that causes injury to the face: facial emphysema, a condition seen both in adults and children. Potentially deadly because it can restrict air supply, facial emphysema - either from a repressed sneeze, anesthesia, or some dental work - can create deep air spaces in the face and neck, sometimes extending as far as into the lungs. Signs are typically facial and/or neck swelling and discomfort and medical treatment should be sought immediately.

[danny_galaga]

I know of a more modern example, which I read in a book and probably won't find by googling. That is, by the end of thirties, Mercedes Benz were making such high performance racing cars, using such specialised techniques, that some of the welding techniques on suspension and crankcase components in particular are un-repruducable nowadays. No one knows how to do those welds anymore!

[AtomSmasher]

It used to be the proper way to hold a steering wheel was a 10 and 2, but that is actually unsafe since the invention of airbags because it will cause your arm to go into your face if the airbag is deployed.  The preferred hand location is now 9 and 3 or if the car has power steering than 8 and 4 is also acceptable.

[drventure]

Back in the 70's, everyone knew that the best place to ride in a big ol' 4 door buick sedan was on that shelf behind the rear seat.

You don't see much of that these days 

[ChadTower]

For example, and the only few I can think of off-hand:

 1) Tilting the head back when you have a nose bleed.

Ugh.  When I was a small kid I used to get nosebleeds in my sleep from the dry forced air heat system in a place we lived.  Some times I would wake up in the middle of the night and start puking up blood because my nose had been bleeding backwards while I was lying down.  That's some scary ---steaming pile of meadow muffin--- when you're 5.  In the movies, when someone starts bleeding from the mouth, they usually die...

[TOK]

How about The Healty Tan? Don't hear much about that anymore!