When we sanitize surfaces, it reduces the number of bacteria on a surface by a certain percentage. That percentage is written in terms of “log reduction.”
In an earlier post, we mentioned that when we sanitize surfaces, it reduces the number of bacteria on a surface by a certain percentage. That percentage is written in terms of “log reduction”—in the case of sanitizing, log3, or a 99.9 percent reduction.
If we disinfect that same surface using an EPA-registered disinfectant designed to eliminate those specific bacteria and pathogens, the percentage of bacteria reduced using the disinfectant is written as log5, or 99.999 percent.
Sounds a bit complicated, but we will explain what this all means in a moment.
For right now, what we need to know is that in the past, logs were not that important for building managers, or for that matter, most cleaning professionals, to understand. In most cases, just effectively cleaning a surface—which is the removal of visible soils—was all that was necessary to keep a facility clean and healthy.
But COVID has brought all of us front and center, realizing the need to clean for health in addition to removing visible soils. It is the pathogens we cannot see, like those that cause the coronavirus, that are now our paramount concern.
Further, we must remember, the coronavirus is not the only dangerous pathogen we must eliminate on surfaces. Cleaning for health is an ongoing journey, requiring astute cleaning contractors to remain vigilant in their efforts to keep building users healthy.
Now, let’s get a better understanding of what logs are all about and how they apply to sanitizers and disinfectants.
Scientists use the “logarithmic scale” to measure the reduction of bacteria on a surface. Each number on the log scale stands for a 10-fold reduction. The first such scale was the Napierian logarithm scale published in 1614. The natural log scale, a variation on the Napierian scale, is most often used today.
These scales are helpful because they can make large numbers more manageable. And when we are talking about microorganisms, we are often dealing with exceptionally large numbers.
For example, let’s suppose 1 million MRSA bacteria are found on a patient’s bedstand in a hospital. While that may sound like a lot of bacteria, depending on shape and elevation, that colony could be no bigger than a dot on a page.
Now let’s suppose we are part of the cleaning crew, and we want to get rid of that colony. Using different cleaning, sanitizing, and disinfecting methods and products, we could achieve the following results:
•Log1: Reduces the number of bacteria on a surface by 10 times.
•Log2: Reduction is 100 times smaller.
•Log3: 1,000 times smaller.
•Log4: 10,000 times smaller.
•Log5: 100,000 times smaller.
•Log6: 1 million times smaller.
Above a log6 and higher is sterilization. However, in most cases, sterilization is required only for such things as medical equipment or tools used in laboratories. When we sterilize equipment such as medical equipment, 100 percent of all bacteria is removed from the equipment.
In the professional cleaning industry and in most settings, we rarely go beyond a log5 reduction. In fact, before COVID, we typically were fine using a log3 sanitizer. In most cases, using a log3 sanitizer means the number of pathogens on that surface are brought down to a safe level, so illness is unlikely to occur.
Due to the pandemic, it is crucial that we use log5 disinfectants and that those, as we have mentioned before, are certified by the EPA to be effective at killing the coronavirus.
This is a key part of the Secure Clean infection control program, whether we are cleaning and disinfecting surfaces manually or using electrostatic sprayers. These additional steps help us eliminate the viruses and pathogens that cause COVID-19 and many other diseases.
The Secure Clean blog is designed to help building managers address the COVID-19 pandemic and keep their facilities cleaner, healthier, and safer, in the most cost-effective way possible. To contact call 888-609-1410.
