What ATP testing tells you, and what it doesn't.
The short version
An ATP test tells you how much organic residue is on a surface. Lower numbers mean cleaner. It's fast, it's objective, and it's best used to compare the same spot before and after cleaning.
How it works
ATP (adenosine triphosphate) is an energy molecule found in living cells and in the residue they leave behind. A swab picks it up, the meter makes it glow, and the meter turns the light into a number. Handheld meters show the result within seconds.
Who uses it
Hospitals use ATP testing to check how well patient rooms are cleaned, and food plants use it on equipment. The CDC has recommended that hospitals monitor cleaning performance, and ATP testing is one recognized way to do it.
Its limits
- It can't tell live germs from dead ones, or bacteria from food residue.
- It isn't a test for any particular virus.
- There's no single "clean" number. Each meter brand uses its own scale, so readings from different brands can't be compared.
- Leftover cleaning chemicals can push readings up or down, so the timing of the swab matters.
How to read your results
Compare each spot's before and after, measured with the same meter. A big drop on the same surface is the clearest sign the cleaning worked.
Sources: Infection Control Today; Hydrite, ATP swabbing methods.