WHY YOU SHOULDN’T PEE IN A POOL
If asked to describe a pool’s odor, you might say it smells like chlorine. But it’s not that simple. That familiar summertime smell is really from a toxic gas trichloramine (NCL3) that forms when chlorinated water reacts with uric acid, a compound found in urine and sweat. Another toxic gas cyanogen chloride (CNCl) also forms when uric acid reacts with chlorine in water.
“Uric acid and these toxins were found in every pool we’ve ever studied,” says Ernest Blatchley, a professor of environmental engineering at Purdue University in Indiana, who studies water quality. Many people think it’s OK to urinate in a pool because of the added chlorine. But they’re wrong, Blatchley says.
Chlorine kills bacteria—it doesn’t counteract human bodily fluids. He estimates that 93 percent of the uric acid detected in the pools he has studied came from human sweat and urine. A crowded pool means a lot more pee, which, in turn, means up to four times the amount of the toxins. “When someone breathes [these chemicals] in, their eyes might water, they might cough, and their skin might feel irritated,” says Blatchley. Extremely high levels of fumes can cause people to lose consciousness.
To prevent the toxins from forming, Blatchley says to shower before swimming. Doing so removes the uric acid left behind on their skin from sweating. And—though this might seem obvious—don’t pee in the pool! “It doesn’t take a lot of effort,” says Blatchley.
WHY WET DOGS SMELL
You’re not the only one who enjoys a cool dip on a hot summer day. Dogs like to go for a swim too. But our four-legged friends don’t usually smell so great when they’re soggy.
This signature stench comes from several different sources, says William Miller, a veterinarian and professor of dermatology at Cornell University’s college of veterinary medicine in New York. One common cause is a waxy secretion called sebum. This natural skin and fur moisturizer is made inside sebaceous glands found under the dog’s skin.
The skin is also covered with a normal flora, or population of bacteria and yeast. These microscopic organisms dine on the sebum. Miller explains that this changes the sebum’s composition, making it stink.
As water evaporates from a wet dog’s skin, tiny particles of this smelly stuff hitch a ride on water vapor. Eventually it makes its way into our nasal passages.
Dogs with long coats smell more because their hair traps more moisture, encouraging bacteria and yeast to replicate. “Dogs with short coats don’t develop a body odor as easily because their skin stays fairly dry,” he says. What should you do if your pooch starts to stink? Miller says to bathe the dog. But if that doesn’t work, try clipping its fur to reduce the moisture near its skin. If your dog still stinks, a vet should rule out an infection or other conditions that could be causing the foul odor, he says.
HOW TO SKIP A STONE
Each summer, stone skippers go head-to-head at a competition on Mackinac Island in Michigan (above). While their results have been impressive, few can compare to pro stone skipper Maxwell Steiner, 23. He started skipping stones for fun as an 8-year-old growing up in Michigan. Little did he know that he would someday hold a world record, with 65 skips by a single stone. (His record was recently broken with 88 skips, but Maxwell says he plans to challenge it this summer.) What’s his secret?
“To skip a stone, I use the ‘Grip it and rip it’ method,” Maxwell says. “You just grip the outside of the rock as tight as you can and throw it as hard as you can.”
Tadd Truscott, a professor at Utah State University, published a study about the physics of stone skipping. He says to use your forefinger to spin the rock so it rotates like a Frisbee. Spin gives the stone angular momentum. This force keeps the stone at a fixed angle as it moves forward. Truscott says that throwing a stone so it hits the water at a 20-degree angle results in the most skips (see The Perfect Throw below).
When the stone hits the water, it pushes the liquid downward. This creates a small indentation at the surface. The water quickly pops back up, forming a wave. The wave, combined with the stone’s forward momentum, pushes the rock up and forward. Gravity then pulls the stone back down to repeat the process. With enough momentum, the rock will keep hopping along the water. But eventually, the stone loses momentum and gravity pulls it underwater. “Gravity always wins,” says Truscott.