What is a disinfectant?

A disinfectant is a chemical or physical agent that kills or inactivates harmful microorganisms like bacteria, viruses, and fungi on inanimate surfaces and objects, reducing them to safe levels, though it may not kill all bacterial spores like a sterilant does. Disinfectants are different from cleaners and antiseptics, cleaners remove dirt and many germs through soap and physical scrubbing but do not necessarily kill them, antiseptics kill germs on living skin and tissues like hand sanitizers and wound cleaners, while disinfectants are for non-living surfaces like countertops, floors, and medical equipment. To be called a disinfectant in the US, a product must be registered with the EPA and proven to kill 99.9 percent of specific microbes with a specified contact time where surface must stay wet, such as 30 seconds to 5 minutes. Common disinfectants include bleach, alcohol, quaternary ammonium compounds, hydrogen peroxide, and iodine. Hospitals use hospital-grade disinfectants that are stronger and effective against tough organisms like tuberculosis and MRSA, and for rooms that were negative pressure isolation for airborne diseases, they use terminal cleaning with these disinfectants plus sometimes UV-C light or hydrogen peroxide vapor. Disinfectants work by disrupting microbial cell walls, proteins, or DNA. They can produce fumes that irritate lungs, so good ventilation and HEPA air filtration help reduce inhalation risks, and you should always clean surface first before disinfecting for best effectiveness.