Keep our body outside and inside clean are necessary

Leviticus 15:1-15
Any man has an unusual bodily discharge, such a discharge is unclean.
If the man with the discharge spits on anyone who is clean, they must wash their clothes and bathe with water, and they will be unclean till evening.
When a man is cleansed from his discharge, he is to count off seven days for his ceremonial cleansing. On the eighth day he must take two doves or two young pigeons and come before the Lord to the entrance to the tent of meeting and give them to the priest.
Why?
Regulations are given for both normal and abnormal, possibly malignant (惡性) discharges. Washing is prescribed both to prevent infection and to sterilize(消毒).
Seven days for observing and the eighth day could be atonement through the priest.
How?
Take bath everyday is good to prevent infection and sterilize. Keep our body outside and inside both clean is necessary.