Date: 201706
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed As Precaution; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: When we reached cruise and about 15 minutes  later the aft Flight Attendant (FA) called to report a sulfur smell in the aft galley. He also mentioned that his throat was itching. I asked him to have another FA verify what he smelled; which they did. Then I had them move through the cabin to see if it was anywhere else. They said they smelled it as far forward as row three. No passengers were complaining. We (in the cockpit) started discussing options in case a source could not be found; ZZZ was coming up on our right wing so we decided that would be our go to airport. During this time we exchanged several calls with the FAs and they thought it was getting worse; we decided to begin the divert process ZZZ; we informed dispatch what was going on and asked for a mechanic to see if they had any thoughts. Since we had lots of gas we asked to descend to start burning fuel. Again the FAs kept calling informing us the smell had changed to a propane smell and their symptoms were getting worse. At this point we [advised ATC] and expedited to ZZZ. We headed to ZZZZZ Intersection on the ILS to hold and burn fuel at 10000 feet. We kept checking with dispatch via ACARS and communicating with the FAs during the entire descent. We ran the overweight landingchecklist just in case. When the FAs called and told us that they were feeling lightheaded and a haze was forming we decided to land overweight. We informed ATC that we wanted emergency vehicles to follow us down runway and to gate; also told them we planned a normal landing but we were overweight.We flew in visually and landed uneventfully; taxied to gates and the EMTs came on board. We elected to take everyone off the aircraft including a FAs to be checked out in the passenger waiting area. No passengers needed attention and the FAs checked out just fine. We spoke with Maintenance; dispatch; and the duty phone; scheduling had rooms for us and the night chaos ended! Everyone involved did a great job of communicating and having things ready; we were very impressed. We used all our resources except [inflight medical service]; which we thought of later. CRM was great; FAs did a great job.


Second narrative: [Report narrative contained no additional information.]


Synopsis: A320 flight crew reported a sulfur smell in the aft galley causing the flight attendants to become light headed.