Cleaning services might use any variety of agents to leave your home or office spotless. But one of the most reliable tools in a cleaner’s arsenal is one that not many people understand: bleach.

What Is Bleach?

Technically, a bleach is any substance that fades the color from something, but when we refer to bleach, we’re usually talking about one of two substances:

• Chlorine bleach, based on sodium hypochlorite. This starts with simple saltwater, whose sodium and chloride atoms are forcibly separated by a strong electric current before being reintroduced to create a reaction that sticks an oxygen atom from the water into each new sodium and chloride sandwich.
  
• Oxygen bleach, based on hydrogen peroxide. This is more difficult to make and more expensive, but it is far gentler—so much so that dentists use it as a teeth whitener. Also, when laundry bleach is advertised as safe for colors, it’s most likely an oxygen bleach.
  

The stain-fighting power of both kinds of bleach stems from their ability to break down the parts of molecules that reflect color, or chromophores, by yanking away their electrons. Bacteria has just as much to fear. Exactly as they would under high heat, the intricately folded protein molecules that make up a bacterium begin to unravel and then permanently clump, much like an egg solidifying as it boils. The microbes then die off, making bleach an effective disinfectant.

Bleach Body

People have been harnessing the disinfecting properties of bleach since the first half of the 19th century, but nobody fully understood how bleach disabled germs until 2008, when a team of researchers led by Dr. Ursula Jakob documented the process. In an interview with NPR, Dr. Jakob explained that, by inventing chemical bleach, humans had actually recreated a germ-fighting chemical that already evolved inside their bodies over thousands of years.

The active ingredient in chlorine bleach, hypochlorite, is already produced by the human immune system to break down the proteins of invading germs, just as it does on a dirty kitchen counter or anything touched by a baby.