E. coli prevalence on the surfaces of zone
2 increased from the start of production (2.6%) to its maximum
level (5.6%) during production.
It should be noted that the contamination
level can double in only a few hours once production
started, from both immigrant cross contamination and growth of
the in situ (resident) pathogens itself.
Nevertheless, the E. coli prevalence
was lower at the end of the day