Blowers vs Towels

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This is more microbiology than chemistry but it has been a subject that fascinated me. Electric hand dryers in public toilets have long been touted as more hygienic than paper towel.

Not so, it seems.

[Wikipedia] In 2008, a study was conducted by the University of Westminster, London, to compare the levels of hygiene offered by paper towels, warm air hand dryers and the more modern jet-air hand dryers .

The key findings were:

• after washing and drying hands with the warm air dryer, the total number of bacteria was found to increase on average on the finger pads by 194% and on the palms by 254%
• drying with the jet air dryer resulted in an increase on average of the total number of bacteria on the finger pads by 42% and on the palms by 15%
• after washing and drying hands with a paper towel, the total number of bacteria was reduced on average on the finger pads by up to 76% and on the palms by up to 77%.

The scientists also carried out tests to establish whether there was the potential for cross contamination of other washroom users and the washroom environment as a result of each type of drying method. They found that:

• the jet air dryer, which blows air out of the unit at claimed speeds of 400 mph, was capable of blowing micro-organisms from the hands and the unit and potentially contaminating other washroom users and the washroom environment up to 2 metres away
• use of a warm air hand dryer spread micro-organisms up to 0.25 metres from the dryer
• paper towels showed no significant spread of micro-organisms.

And, yes, the work has been replicated.
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Is Coca Cola evil?

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Got an email from a friend recently, spouting the old and hoary myths about Coca Cola. My comments are in blue.

1. In many states the highway patrol carries two gallons of Coke in the truck to remove blood from the highway after a car accident.
Why would they? Water is cheaper and as effective. But don't take my word for it - as a patrol man. But be ready to be laughed at.

2. You can put a T-bone steak in a bowl of coke and it will be gone in two days.
No, it wont. But don't take my word for it. Put a piece in Coke and watch it get wet and soggy before you eyes. But it wont dissolve. Only use a small bit, no sense in marinading a whole steak.

3. To clean a toilet: Pour a can of Coca-Cola into the toilet bowl . . . Let the "real thing" sit for one hour, then flush clean.
Probably will. It is a weak acid and the stains are generally acid soluble. So what. Orange juice would probably do the same.

4. The citric acid in Coke removes stains from vitreous china.
See 3, though Coke is more commonly phosphoric acid.

5. To remove rust spots from chrome car bumpers: Rub the bumper with a crumpled-up piece of Reynolds Wrap aluminum foil dipped in Coca-Cola.
See 3.

6. To clean corrosion from car battery terminals: Pour a can of Coca-Cola over the terminals to bubble away the corrosion.
Again, so what? Any carbonated drink will do this. Best use soda water so that you don't get a sticky battery.

7. To loosen a rusted bolt: Applying a cloth soaked in Coca-Cola to the rusted bolt for several minutes.
Never managed to get this to work myself. Eucalyptus Oil works a treat, though.

8. To bake a moist ham: Empty a can of Coca-Cola into the baking pan;rap the ham in aluminum foil, and bake. Thirty minutes before the ham is finished, remove the foil, allowing the drippings to mix with the Coke for a sumptuous brown gravy.
Yum. Is this a bad thing?

9. To remove grease from clothes: Empty a can of coke into a load of greasy clothes, add detergent, And run through a regular cycle. The Coca-Cola will help loosen grease stains. It will also clean road haze from your windshield.
Most detergents are phosphate based. So is Coke. Is there enough phosphate to act as a detergent? It certainly can't hurt.

FYI: 1. The active ingredient in Coke is phosphoric acid. It's pH is 2.8. It will dissolve a nail in about 4 days.
No it wont. I tried it and the nail was still there 4 years later. Ditto a copper coin.

The pH of your gastric juices can be as low as 1. That's six times stronger than Coke.

2. To carry Coca Cola syrup (the concentrate) the commercial truck must use the Hazardous material place cards reserved for Highly Corrosive materials.
Your point being? The same applies to trucks carrying vinegar concentrate.

3. The distributors of coke have been using it to clean the engines of their trucks for about 20 years! Drink up! No joke. Think what coke and other soft drinks do to your teeth on a daily basis. A tooth will dissolve in a cup of coke in 24-48 hours.
Any carbonated soft drink will help dislodge muck from anything. It's the bubbles what do the job.

Teeth? Nope, sorry. Not enough acid in the drink to do that.
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Of vampires and garlic.

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"Vampires are feared everywhere, but the Balkan region has been especially haunted. Garlic has been regarded as an effective prophylactic against vampires.

We wanted to explore this alleged effect experimentally.

Owing to the lack of vampires, we used leeches instead. In strictly standardized research surroundings, the leeches were to attach themselves to either a hand smeared with garlic or to a clean hand. The garlic-smeared hand was preferred in two out of three cases (95% confidence interval 50.4% to 80.4%). When they preferred the garlic the leeches used only 14.9 seconds to attach themselves, compared with 44.9 seconds when going to the non-garlic hand (p < 0.05).

The traditional belief that garlic has prophylactic properties is probably wrong. The reverse may in fact be true.

This study indicates that garlic possibly attracts vampires."

Tidsskr Nor Largeforen. 1994 Dec 10;114(30):3583-6.

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Ah, now I see!

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A Sydney doctor has been studying human retinas since 1976 and says the carrot myth, that eating carrots is good for your eyes, started in World War II, is a "complete fabrication". Dr Beaumont is the director of the Macular Degeneration (MD) Foundation.

"When the English ... were flying at night they used radar but the Germans didn't know that radar existed," Dr Beaumont said from his Sydney clinic. "The English certainly didn't want them to know so they put out a myth saying they were feeding their pilots carrots to improve their night vision and that's why they could fly and see things at night.

Dr Beaumont recommends eating lutein rich foods for eye health. The lutein (found in spinach, corn and egg yolks) helps protect the eye from sight-damaging light that causes MD and blindness, Dr Beaumont explains.

On the flipside, ironically, foods rich in beta carotene - like carrots - can damage the eye's protective shield, doubling your risk of contracting the disease.

So much for old wive's tales.

Related to that, there is at least one recorded case of a person dying from drinking excessive amounts of carrot juice.

While we need Vitamin A (beta carotene is a Vitamin A precursor), it is actually quite toxic.
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