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Cleanliness measurement: Updated ATP study

September 19, 2010
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In July 2008, I explored the idea of scientific measurement of cleanliness through a creatinine measurement protocol (urine concentration) and concluded that it was a very limited tool.

The focus of that article was restroom cleanliness and contamination levels, based on urine residue (creatinine sampling).

Due to the limitations of that measurement protocol, I suggested that a more comprehensive testing strategy could be measures of adenosine triphosphate (ATP).

This article examines a broader cleanliness study using the ATP testing model suggested in that article.

What is ATP?
ATP is present in all organic material and is the universal unit of energy used in all living cells.

ATP is produced and/or broken down through metabolic processes in all living systems.

Processes, such as photosynthesis in plants, muscle contraction in humans, respiration in fungi and fermentation in yeast, are all driven by ATP.

Therefore, most foods and microbial cells will contain some level of naturally occurring ATP.

This testing protocol measures bioluminescence, or Reflective Light Units (RLU), to detect residual ATP as an indicator of surface cleanliness.

The presence of ATP on a surface indicates the presence of contamination, including food residue, allergens and/or bacteria.

Ineffective cleaning processes are the primary reason for high levels of ATP.

The ATP study: Types of space
We conducted a cross-industry study in about 8,000,000 square feet of multi-building facilities, including an international airport, a leading university and a national health research complex.

As part of this study, we tested 32 different types of space, including restrooms highlighted in our previous article.

On the basis of the ATP findings, there were four other types of space with higher contamination levels than restrooms.

These areas, in order, were: Baggage claims, elevator lobbies, building entrances, libraries, and restrooms.

All of these areas have higher than normal traffic and high-touch space.

While we often see complaints more related to restrooms, it is clear that, based on the typical levels of contamination, other types of space ought to have an equal or greater priority for the cleaning program.

These ATP findings were also compared to the level of visible soiling found in these same rooms to test if there was a connection between ATP levels and visible soil.

It turns out there is only a loose connection between these two data sets.

For example, libraries, which had a very high ATP rating, scored a respectable 85 percent cleanliness level based on visible soiling.

Baggage claim areas scored an 87 percent cleanliness level while testing very high for ATP.

In other cases, break rooms, general offices, lounges and stairways contained unacceptably high levels of visible soiling while posting low levels of ATP.

Clearly, an effective cleaning program needs to respond to both contamination and visible soiling conditions.

Time of day and items cleaned
We further cross analyzed ATP levels between 8:00 a.m. and 4:00 p.m.

The highest levels of ATP (over 1000 RLU) occurred at 9:40 a.m., 10:56 a.m. and 12:19 p.m.; with the highest levels occurring between 8:00 a.m. and 12:45 p.m.

Clearly, the need for a day shift operation could be beneficial.

All-in-all, 75 different classes of items and surfaces were tested during our study.

Some have suggested that an ATP level of 30 RLU or less on food preparation surfaces is an acceptable standard.

In our study, 71 percent of the items and surfaces measured would fail to meet that goal.

And, 47 percent of all items and surfaces tested had ATP levels over 100 RLU.

The highest ATP levels (500 RLU and above) were found on just five surfaces: Area rugs, baseboards, ceilings, hard surface floors, and food counters.

Continuing the journey
On this journey of measuring cleanliness in our facilities, we have utilized visible attributes, creatinine concentrations and now ATP (adenosine triphosphate) testing.

Certainly, there is more to be done in creating an integrated cleaning measurement system.

I believe we are ready for a better way to measure cleaning efficacy and a new group of professionals is addressing the issue.

The Integrated Cleaning and Measurement™ (ICM) group has been formed.

This authoritative group of professionals will focus on the singular issue of greater cleaning effectiveness through integrated measurement strategies.

The ICM Symposium is having its second meeting this month in Las Vegas.

Organizers include the Housekeeping Channel ( and the IEHA (

I''ll be there because that''s where real measurement alternatives will be discussed by real professionals.

Vincent F. Elliott is the founder, president and CEO of Elliott Affiliates, Ltd. of Hunt Valley, MD, He is widely recognized as the leading authority in the design and utilization of best practice performance-driven techniques for janitorial outsourcing and ongoing management.

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