Household bleach, also known as sodium hypochlorite, is a common and effective disinfectant in domestic, medical and food environments. The active ingredient is chlorine, a powerful oxidizer. By itself, it is a toxic corrosive gas, but when coupled with hypochlorite, the chlorine is released slowly over time and is not toxic. This is why bleach has an expiration date - do check that you are using bleach that is within a year of it’s listed date.
**When you make a 1:5 diluted bleach solution to disinfect something, it will lose its effectiveness over about 24 hours, so to disinfect surfaces, make a new small batch every day. A 1-in-5 dilution of household bleach with cold water (1 part bleach to 4 parts water) is effective against many bacteria and some viruses, and is often the disinfectant of choice in cleaning surfaces in hospitals. This 1:5 dilution though smelly, is not a danger to breathe, though it is inadvisable to breathe more concentrated levels, and could harm the lungs. Because of it’s reactive instability, bleach does it’s disinfecting job quickly, and then decomposes into salt and water, and so has a negligible effect on the environment. It’s safe to pour your dilution down your sink, or throw the paper towel wipe away in the trash. Bleach is heat and light sensitive, which is why bleach comes in opaque bottles. Keep the concentrate in a cool dark area, and away from children. 3/25/20: UPDATE FROM A TOXICOLOGIST - FOR OLDER BLEACH, IT CAN STILL BE EFFECTIVE, JUST USE A LOWER DILUTION. MAYBE 1:2 (MORE THAN 3 YRS OLD) OR 1:3 (1-3 YRS OLD) OF BLEACH TO WATER.
How does bleach disinfect? By oxidation, which is a process that breaks apart organic molecules, such as viral structural proteins. Bleach acts to oxidize or attack the outer layer of viruses, breaking the spikes off, and punching holes in the protein coat (I love this visual!!) The crippled virus is then incapable of binding to target cells (like our throat or lung endothelium).
Instructions say to leave the 1:5 diluted bleach on the surface for 5 minutes, rinse, then wipe dry. Kinda tough for doorknobs, elevator buttons and other vertical surfaces over ‘discolorable’ carpets. (Although at this point, it might be silly to get precious about old crappy carpets.) I’m going to get a spray bottle, and put floor protectors like old rags under the doorknob areas when I spray them, and remove the rags afterwards.
From another article on how long Covid19 lasts on surfaces: “…disinfectants with 62-71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite (bleach) can "efficiently" inactivate coronaviruses within a minute, according to the study. "We expect a similar effect against the 2019-nCoV," the researchers wrote, referring to the new coronavirus. But even though the new coronavirus is a similar strain to the SARS coronavirus, it's not clear if it will behave the same.
Diluted household bleach solutions, alcohol solutions containing at least 70% alcohol and most EPA-registered common household disinfectants should be effective at disinfecting surfaces against the coronavirus, according to the CDC. The bleach solution can be prepared by mixing 5 tablespoons (one-third cup) of bleach per gallon of water or 4 teaspoons of bleach per quart of water, the CDC wrote in a set of recommendations.”
DO NOT:
A few cautions. Only mix bleach with cold water. Hot water will decrease its effective time window.
Bleach should never be mixed with vinegar or other acids as this will create highly toxic chlorine gas and can cause severe burns internally and externally (think World War I trenches - no no no!) Mixing bleach with ammonia similarly produces toxic chloramine gas, which can burn the lungs. Mixing bleach with hydrogen peroxide results in an exothermic chemical reaction that releases oxygen, and may cause the contents to splatter and cause skin and eye injury. Heating bleach and boiling it may produce chlorates, a strong oxidizer which may lead to a fire or explosion.
