Logarithmic reduction

Food safety researchers have to think in orders of magnitude, by necessity. Instead of aiming to completely wipe out a population of microbes, they’re trying to achieve a relative decrease as measured in orders of 10.
A 1-log reduction would be a 10-fold decrease — so, 90 percent fewer germs. A 2-log reduction is a 100-fold decrease — so 99 percent fewer germs — and 3-log is 1,000 times less, or 99.9 percent fewer. You get the picture.