I agree with the other replies.
Unless the filter technology has changed since I last needed to use on, this is what I think I know:
You can use the filter in your room to suck out the stink and as it sucks out the air in room it is clean when it is blown out into another area.
The dust cover goes on the outside side of the filter to keep larger particles from clogging up the filter. I recommend this.
Or you can suck out the room stink out into another area an it will blow out of the filter that is placed in the other area. No dust cover is need on outside of filter but, it maybe useful on the end of tube that is sucking room out and blowing it through the filter which was placed in another area.
Here's why I recommend putting the filter in grow room: make a fist with and suck on said fist. Now blow on said fist. I find it easier to suck air in than to blow air out.
Sucking air into filter then to blower fan then the air is blown out.... Will make your blower fan last longer.