Air Carrier Captain reported during final descent being notified by F/A 4 that F/A 3 had lost consciousness temporarily due to fumes in the aft cabin. Upon gate arrival Captain submitted a fume report to Maintenance and Flight Attendant crew received Medical evaluation.

Narrative

While being vector to final and at 1;500 feet the F4 (Flight Attendant 4) called the cockpit. The First Officer was pilot flying so I answered the call. The F4 informed me that they were experiencing a fumes event and that the F3 had passed out while exiting the lavatory. (The First Officer and myself were not experiencing any smells or odors). I informed the F4 that we were only about 7 miles from the airport and that we would be on the ground in less than five minutes. I asked the F4 if we needed medical personnel to meet us he said not at that time and that the F3 was conscious. We were next to land I did not declare an emergency and we did not contact med link. After landing and taxing clear of the runway and after completing the after landing checklist I asked the First Officer to call the back and get an update on the F3 and see if we need medical personnel to meet us. The First Officer called back to the inflight and spoke with the F4 who was standing next to the F3 and we both could hear the F3 saying she didn't require or want any medical assistance on arrival. Upon gate arrival we deplaned the 40 customers and no one mentioned smelling anything. After all the customers were off the plane I took the Cabin Odor Report Form to the cabin and discussed the event with the inflight crew. They informed me at that time that they started smelling something shortly after we were descending below 10;000ft. The smell was most noticeable from the emergency exits aft. The F3 had been in the aft lavatory and upon exiting she said she took three deep breaths and then the other flight attendants say she passed out; however the F3 said she only felt light headed but never passed out. During this discussion I was informed that the inflight crew had asked a Deadheading flight attendant to occupy the F3's jumpseat position during landing. After completing the Cabin Odor form I contacted our Dispatcher and Maintenance Control and the duty Chief Pilot. The flight attendants contacted Med Aire and Med Aire advised 3 of the 4 flight attendants to go to the emergency room to get checked out before they would release them to fly again.