Cleaning & Maintenance Management Online

Quantifying Germ Removal

February 8, 2012

Often, a surface appears free of unwanted matter following a cleaning; however, it can be difficult to determine the actual amount of soil removed from said surface.

For years, our measurement devices were our innate senses.

If something did not look, smell or feel clean — hearing and taste are not entirely applicable here — a red flag was raised, necessitating re-work or a change in chemicals and equipment, staff or procedures.

Today, aside from sensory assessment, there are several ways to prove germ removal, including adenosine triphosphate (ATP) meters, particle counters, ultraviolet light testing and log reductions, all of which offer proof of results.

"Using tools to measure and monitor the amount of germs lingering on surfaces is helpful to determine the success rate of cleaning, and it is an important step in the cleaning and disinfecting process," states Kim LaFreniere, Ph.D, associate research fellow for Clorox Professional Products Company.

The Head Of The Class

"While the most accurate method of evaluation and measurement involves culturing samples taken from surfaces, it is simply not practical in application for a cleaning professional under most circumstances," proclaims Peter Sheldon, Sr., vice president of operations for Coverall Health-Based Cleaning System.

Luckily, there is a more practical device that, while not as precise as laboratory work, can deliver actionable data seemingly instantly: The ATP meter.

ATP, first discovered in 1929, is an energy molecule found in all living — or once living — organisms.

According to Tom Morrison, vice president of marketing for Kaivac Inc., ATP testing should be performed both before and after cleaning.

Doing so is twofold: It shows that a surface was cleaned while also shedding light on the effectiveness of the cleaning.

As can be surmised, a low ATP count is preferable — as the gist of cleaning is to remove unwanted matter from surfaces.

A high ATP count means there is potential contamination on a surface, likely resulting from improper cleaning and/or insufficient disinfection.

ATP measurement offers proof of results that can reassure supervisors that their staffs are competently cleaning — and disinfecting where applicable — and help teach frontline custodians the proper techniques for maximum soil and germ removal.

However, according to Lynn Krafft, International Custodial Advisors Network (ICAN) editor and owner of Krafft Cleaning Service, ATP measurement can be costly and instill a false sense of security.

"We live in a sea of microbes, and attempting to remove them or reduce their numbers makes no sense unless there is a real danger imposed by their presence in a specific setting," expresses Krafft.

In high-risk environments like schools and health care facilities, ATP measurement can be quite effective in quantifying germ removal; in an office or industrial facility, it might be unnecessary.

Other Options

Aside from the ever popular ATP meter — which has gone down in cost and increased in accuracy and functionality in the past several years — there are other devices and methods to enumerate the removal of unwanted matter.

• Ultraviolet light

Though it does not produce a number or a percentage, testing an area with an ultraviolet (UV) light will show whether or not a surface is contaminated with any fluorescent substances, which are otherwise invisible to the naked eye.

Many bodily fluids contain fluorescent molecules, as do chemical and mineral residues that may be left behind after insufficient cleaning.

Testing with a UV light is popular in restrooms and is a good way to gauge how much attention a cleaning professional has given to the lavatory.

Quality assurance individuals also use UV lights to analyze cleaners'' work, notably in places like hotel and patient rooms.

• Particle counters

Unlike other devices that detect contamination on surfaces, particle counters detect airborne particulates — a measure of indoor air quality (IAQ).

Sometimes, cleaning can cause matter to become suspended in the air, which will either be inhaled by building occupants or redistributed on surfaces as the matter settles.

With a particle counter, users can confirm the effectiveness of their air scrubbers; high-efficiency particulate air (HEPA) filtered vacuums; heating, ventilation and air conditioning (HVAC) systems; and their general cleaning.

"Monitoring IAQ provides a measure of cleaning effectiveness that is quantifiable and can be shared with the client or tenant," says Bob Croft, president of CBN Building Maintenance.

• Log reductions

Log reduction, a mathematical term showing a reduction in the number of live germs logarithmically, denotes the relative number of live microbes eliminated from a surface after sanitizing, disinfecting or cleaning.

"When it comes to determining actual germ kill, ''inactivation'' or removal, log reduction is important to understand," asserts Morrison.

A 1-log reduction means the number of germs on a surface is 10 times less than it was prior to cleaning; a 2-log reduction means the number is 100 times less; a 3-log reduction is 1,000 times less; and so on up to a 7-log reduction.

A log reduction-based cleaning system can help identify the cleaning processes that work best to achieve desired cleanliness levels in a given timeframe.

The Bottom Line

At the end of the shift, it all comes down to effective cleaning.

According to LaFreniere, custodial professionals should adopt a comprehensive infection prevention and control plan that includes measures such as attention to hand hygiene, surveillance, contact precautions and environmental cleaning and disinfecting.

Regardless of what is used to assess results, the goal is universal: Sufficiently remove unwanted soils — which include germs and bacteria — from the indoor environment.

"Investment in science-based measurement does represent additional costs that cleaning professionals have not historically had," opines Sheldon. "The real question for the cleaning professional is, ''What is the real value of evidence-based cleaning?''"

The various measurement devices available allow for tangible data that either help prove or disprove cleaning efficacy.

This helps custodial professionals cater their cleaning efforts to better achieve cleanliness and hygiene objectives.

And, a clean and hygienic indoor environment equates to happy and healthy building occupants.