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"Log reduction" is a mathematical term
(as is "log increase") used to show the relative number of live microbes
eliminated from a surface by disinfecting or cleaning.
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For example, a "5-log reduction" means
lowering the number of microorganisms by 100,000-fold, that is, if a surface
has 100,000 pathogenic microbes on it, a 5-log reduction would reduce the
number of microorganisms to one.
Log Reductions
1 log reduction means the number of germs is 10 times
smaller (101)
2 log reduction means the number of germs is 100 times
smaller (102)
3 log reduction means the number of germs is 1000 times
smaller(103)
4 log reduction means the number of germs is 10,000 times
smaller(104)
5 log reduction means the number of germs is 100,000 times
smaller(105)
6 log reduction means the number of germs is 1,000,000 times
smaller(106)
7 log reduction means the number of germs is 10,000,000
times smaller(107)
v
Another way to look at it is: 1-Log Reduction
would reduce the numberof bacteria 90%.
v
This means,
for example, that 100 bacteria would bereduced to 10, or 10 reduced to 1.
Example:
1 log reduction = 100( bactreia) to 1log reduction = 100-10
=90 kill the bactria
1000( bactreia)= 2log
reduction = 1000-100 =900 kill the bactria
= Log =10 10 X10 =100
=log=10 10 X 100 =1000
EX:
Log Reduction (LR) = log10 (107) – log10 (105) =7-5 =2
