People and their activities are considered the biggest source of pollution. On the one hand, human pollution to the environment indirectly affects the number of bacteria carried by products. On the other hand, in some production operations, personnel and material contact, direct contamination of products, affecting the degree of microbial contamination before sterilization of products. Production operators should have basic microbial knowledge, develop good hygiene habits, and wear protective clothing correctly according to the requirements of clean environment; Equipment design, process flow and production operation design should minimize the risk of contamination by personnel and production operators.