In light of the recent launch of the ISSA Clean Standard, the Healthy Facilities Institute (HFI) provided ATP Sampling Tips from its SMART - Swift Market Assessment Response Team – Committee in conjunction with the nonprofit IEHA.
According to Dr. Jay Glasel, Professor Emeritus in the Department of Microbial, Molecular and Structural Biology at the University of Connecticut Medical School in Farmington, Connecticut, and Managing Member and Founder of Global Scientific Consulting, LLC:
“ATP swabs are widely used in the cleaning industry to perform an Integrated Cleaning and Measurement (ICM) program and are part of the ISSA Clean Standard… [However] swab sampling [can have] a very large number of variables that can affect the meaning of the contamination data derived from swab samples… [For example,] if the swab sampling pickup and deposit efficiencies vary greatly from sample to sample, the data becomes meaningless no matter how many samples we obtain even though the samples are scored using a perfectly accurate instrument - for example, an ATP luminometer. This is another example of ‘garbage in, garbage out’.”
How do you ensure consistency in ATP measurement?
According to ISSA:
The selection of the actual high touch points that will be tested [using an ATP device] should be done randomly and in a manner that ensures that selected areas are located throughout the facility. For example, test 5% of the desks in a classroom.
Create a template to control the area to be tested with the ATP swabs. A template can be made from cardboard or poster board by cutting out a square 2 inches by 2 inches (5 cm by 5 cm) in dimension, and placing this over the surface to be swabbed.
For irregular surfaces (such as door handles) it may not be feasible to use a 2” x 2” template. In such cases, swab as much of the surface as possible.
The ATP swabs should be rubbed back and forth, covering the entire 2” x 2” area, first left to right, then top to bottom.
Maintain records of your ATP results noting the ATP value, the high touch points tested, and the date.
According to one ATP device maker: “Several manufacturers of ATP devices recommend a 4” x 4” template for flat surfaces, but the real key is consistency, no matter which template size is used.”