What is Log Reduction?

What is Log Reduction?

‘Log’ stands for logarithm, a mathematical term for a power to which a number can be raised. For example, if using 10 as a given number, a Log 3 increase can be shown as 103

A log reduction takes the power in the opposite direction. Log reduction means a 10 fold (one decimal place) or 90% reduction in the quantitative value of a microbial population. In simple terms 1-Log Reduction would reduce the number of bacteria 90%. For example, 100 bacteria would be reduced to 10, or 10 reduced to 1. Log reduction = log10 (N0 /N) Where: N0 = colony forming units of the microorganisms before disinfection N = colony forming units of the microorganisms after disinfection.

Log Reduction Chart Log Reduction Reduction Factor Percentage Reduced 1 10 (10) 90.0% 2 100 (10x10) 99.0% 3 1,000 (10x10x10) 99.9% 4 10,000 (10x10x10x10) 99.99% 5 100,000 (10x10x10x10x10) 99.999% 6 1,000,000 (10x10x10x10x10x10) 99.9999%