Leviticus 15

Leviticus 15 rounds out the rules for impurity and cleanliness.

If a man has an "unusual discharge", him and everything he touches is unclean while it is going on. Similarly, a woman who is having her monthly period is unclean and everything she touches is unclean.

In both situations, they must offer two birds, one as a sin offering, and one as a burnt offering in the cleansing ceremony. Since this is a regular occurrence for women, it's good that they only have to offer up two birds each time this happens and not, say a bull. That would get expensive.

Two situations that do not require offerings but they are unclean: male ejaculations and when two people have sex. They are just unclean until evening.

Since the gist of these rules is human health and hygiene, it is tempting to say that is the full limit and purpose. However, Lev. 15:31 cautions that Israelites are to avoid unclean things so they that do not die for defiling God's dwelling place. I interpret this to mean that bringing unsanitary conditions into God's tabernacle would result in death. This would suggest that unsanitary conditions has some sort of holiness downgrade that.