צו את בני ישראל וישלחו מן המחנה כל צרוע וכל זב וכל טמא לנפש
במדבר ה – ב
What
To send a Tamei out of the Machane Shechina in the Midbar
Type
Positive
When
Any time
Where
In the Midbar in the Machane Shechina, afterward in the Bais HaMikdash and the Azarah. For the Mikdash and Azarah are the Machana Shechina after the Midbar.
Who
Males and females.
Why
Because Tumah diminishes the wisdom of its carrier and separates him from 'understanding' and from the 'upper wisdom'. Therefore it isn't appropriate for a Tamei to stand in front of the Shechina.
Levels
1. A Metzora must be sent out of all three Machanos or out of Yerushalayim.
2. Zavin, Zavos, Yoledes, and Nidos are sent out of 2 Machanos, the Machane Shechina and Leviya or out of the Har HaBayis.
3. Tamei Meis, Boalei Nidosis and all Goyim are only sent out of the Machane Shechina or the Azarah and the Chayil.
4. A Tevul Yom is sent out of the Ezras Yisrael and Ezras Nashim.
5. A Mechusar Kippurim is sent out of the anywhere further in than the Ezras Yisrael.
2. Zavin, Zavos, Yoledes, and Nidos are sent out of 2 Machanos, the Machane Shechina and Leviya or out of the Har HaBayis.
3. Tamei Meis, Boalei Nidosis and all Goyim are only sent out of the Machane Shechina or the Azarah and the Chayil.
4. A Tevul Yom is sent out of the Ezras Yisrael and Ezras Nashim.
5. A Mechusar Kippurim is sent out of the anywhere further in than the Ezras Yisrael.
Nowadays
We must send out any Tamei from the place that the Bais HaMikdash and Azarah are supposed to be.
Additional details
In the first Perek of Keilim
If one transgresses
He has neglected to perform the positive commandment of וישלחו מן המחנה. In addition he has transgressed the negative commandment of ולא יטמאו את מחניהם
Stringency
The Torah repeats this Mitzva a few times to emphasize its stringency