Why Clean First?

April 20, 2020


Larry Beaver, Ph.D.

RSC Bio Solutions

In these trying times, we are all looking for better ways to keep our homes and workplaces safer.  Often sanitizing (making clean and hygienic) living and work spaces was a consideration only after other more basic, more superficial cleaning needs were met.  The current crisis has brought more attention to cleaning and disinfection of surfaces to not only enhance appearance, but to ensure our safety.  Now it’s not just about appearance; our health is at stake.

Health and safety experts agree that thorough cleaning and disinfection of living and work spaces, including public areas such as lobbies, transit areas, stores, churches and medical facilities is critical to fighting the spread of pathogens such as viruses, bacteria, and mold.  The Centers for Disease Control and Prevention (CDC) provide extensive guidelines for cleaning and disinfection, currently focusing on preventing the spread of COVID-19 (https://www.cdc.gov/coronavirus/2019-ncov/prepare/disinfecting-your-home.html).  This is a timely reminder for all of us that cleaning is a fundamental first step in preparing surfaces for effective use of a disinfectant.

Why is cleaning so critical?  Why not just spray everything with disinfectant?  Why can’t I just clean the surface – it’s just like washing my hands, right?  Facts show, and the CDC, World Health Organization (WHO), and medical professionals agree that cleaning surfaces and then disinfecting them are more effective at fighting disease when used together than when either method is used alone.

Cleaning removes the soils, grease and grime (even when not visible to the naked eye) that harbor and in some cases feed bacteria, mold, and viruses and can serve as a physical barrier, preventing disinfectant from penetrating and killing the pathogens.  Some pathogens create a protective biofilm barrier around themselves.  So even clean-looking surfaces can harbor a biofilm filled with pathogens.  Effective cleaning can physically remove this these barriers from surfaces, leaving behind a much lower loading of pathogens that are now easier to kill since their protective environment has been scrubbed away.

Another benefit to cleaning beyond just physical removal of the pathogens is seen in the way that soaps and detergents can react with some pathogens.  Soaps and detergents are both surfactants (chemical-speak for “surface-active agents”).  Surfactants can chemically disrupt the cell walls of some pathogens and kill them.  This is a side benefit of the cleaning step:  physically wash away much of the danger and kill many of the weak ones that remain prior to application of a disinfectant.

But cleaning alone is only part of the solution.  Some of those remaining pathogens (COVID-19 for instance) are very resistant to the effect of surfactants.  Any virus that remains on the surface following cleaning is still active.  A disinfection step is necessary to kill these remaining viruses and any other pathogens not mechanically removed by the prior cleaning step.  Not only can effective cleaning as a first step remove much of the problem, it makes disinfection more effective because the protection offered by dirt, grease, and grime has been removed.  This is why cleaning and then disinfecting, in that order, are so critical:  cleaning alone cannot remove the pathogens and a disinfectant alone is less effective when dirt and grime or biofilm on a surface serve to encase and protect the pathogens.

Used together, cleaning followed by effective application of a disinfection is an effective weapon against transmission of disease and is a critical part of the disease prevention protocols recommended by the CDC and WHO (https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public).

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