I had a comment posted with the question why they were considered unclean until evening. Great question! I'm glad you asked. Please ask anytime! :)
After I looked in a couple of places the only thing I found is that it allows for people to ceremonially clean themselves and then give them a "brief time of ceremonial purity" and a time of respectful rest....perhaps to keep them clean before entering the temple again and before the sin and uncleanness encroaches upon the holy. Remember, these laws are to really impress upon the Israelites sensitivity to uncleanness and sin...in whatever why that is manifested. They are to be careful about defiling the tabernacle by entering it in an unclean condition.
How's that? Clear as mud? :)
Glad you asked.