How to measure Log reduction

 

The reduction of pathogens is measured in Log – Logarithm.

“Log reduction stands for 10-fold (one decimal) or 90% reduction in numbers of live bacteria.”

 

At a 4 Log reduction, the number of pathogens is 10,000 times less.

5Log reduction means the number of pathogens is reduced, times 100,000.

 

[Source: healthy facilities institute, Log reduction chart]

Log reduction

1-Log reduction: fewer bacteria reduced by a factor 10

5-Log reduction:  fewer bacteria reduced by a factor 100,000