Narrative:

During climbout passing approximately 8;000 feet; in VMC conditions; cabin crew called flight deck and notified me that there was a strong acrid smell of burning rubber in the cabin approximately in rows 12-15 and several passengers had pushed their call buttons due to the smell as well. The flight attendants told me that the smell got worse towards the aft galley. They had initial concerns there might be a problem with an engine so they had run forward to look out the windows and saw nothing abnormal. We immediately asked for a level off from ATC while we looked into the problem. We leveled off at 13;000 feet. The captain decided I should go aft and take a look so we coordinated for a flight attendant to come forward while I went aft to investigate. When I reached the aft half of the cabin; I did smell a slight odor that smelled more like exhaust than burning rubber to me; but it was very slight and barely noticeable. I did not see any smoke or haze. When I asked the flight attendants if they saw any smoke or haze they initially said no. I also asked them if they were feeling ok and they said yes. I then went back to the cockpit and told the captain what I had seen and heard. Our initial thoughts were about the tires since the smell was like burning rubber and we didn't feel like there was any issue about the tires. Since the smell had almost completely dissipated; we were heavyweight; and there was no one claiming any effects; we initially elected to press on to destination; but would continue to monitor the situation. Almost immediately after the captain talked with the flight attendants again; two of the flight attendants (#3 and #4) told the captain they were feeling dizzy and light-headed. We immediately decided we needed to [advise ATC] and return to [the departure airport]. We had the flight attendants query the passengers and we initially determined 8 passengers were claiming they felt ill. We did not smell anything on the flight deck; but we decided I should don my mask as a precaution. The captain flew an uneventful visual approach and uneventful overweight (approximately 154;000 lb) landing and we taxied to the hold bay for aircraft rescue and firefighting (arff) to inspect the aircraft. Arff did not note any damage after inspection. Although arff was prepared to get airstairs and have emts board to check the passengers who were feeling ill. However; when we checked again; only the two flight attendants were feeling ill so arff asked us to taxi back to the gate. We taxied to the gate and EMS checked the two flight attendants and we deplaned the passengers. Although the two flight attendants later reported they felt ok; they were pulled off of the trip. After block-in; I did a post-flight walk around and did not see anything out of the ordinary. We did fill out an online smoke; fume; and odor form and submitted it online. My understanding after talking with management is that a cabin recirculation fan had failed and a circuit breaker had popped and that was the reason for the smell of burning rubber. We did not know this at the time though. We need a better checklist for handling smoke; fumes; or odors as the current QRH seems to be all about eliminating smoke from a possible fire. Although we referenced it; I felt it was inadequate in determining what type of odor was occurring or how to respond appropriately in this situation.

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Original NASA ASRS Text

Title: B737 First Officer reported that there was a smell of burning rubber in the cabin prompting a return to the departure airport.

Narrative: During climbout passing approximately 8;000 feet; in VMC conditions; cabin crew called flight deck and notified me that there was a strong acrid smell of burning rubber in the cabin approximately in rows 12-15 and several passengers had pushed their call buttons due to the smell as well. The flight attendants told me that the smell got worse towards the aft galley. They had initial concerns there might be a problem with an engine so they had run forward to look out the windows and saw nothing abnormal. We immediately asked for a level off from ATC while we looked into the problem. We leveled off at 13;000 feet. The Captain decided I should go aft and take a look so we coordinated for a flight attendant to come forward while I went aft to investigate. When I reached the aft half of the cabin; I did smell a slight odor that smelled more like exhaust than burning rubber to me; but it was very slight and barely noticeable. I did not see any smoke or haze. When I asked the flight attendants if they saw any smoke or haze they initially said no. I also asked them if they were feeling OK and they said yes. I then went back to the cockpit and told the Captain what I had seen and heard. Our initial thoughts were about the tires since the smell was like burning rubber and we didn't feel like there was any issue about the tires. Since the smell had almost completely dissipated; we were heavyweight; and there was no one claiming any effects; we initially elected to press on to destination; but would continue to monitor the situation. Almost immediately after the Captain talked with the flight attendants again; two of the flight attendants (#3 and #4) told the Captain they were feeling dizzy and light-headed. We immediately decided we needed to [advise ATC] and return to [the departure airport]. We had the flight attendants query the passengers and we initially determined 8 passengers were claiming they felt ill. We did not smell anything on the flight deck; but we decided I should don my mask as a precaution. The Captain flew an uneventful visual approach and uneventful overweight (approximately 154;000 lb) landing and we taxied to the hold bay for Aircraft Rescue and Firefighting (ARFF) to inspect the aircraft. ARFF did not note any damage after inspection. Although ARFF was prepared to get airstairs and have EMTs board to check the passengers who were feeling ill. However; when we checked again; only the two flight attendants were feeling ill so ARFF asked us to taxi back to the gate. We taxied to the gate and EMS checked the two flight attendants and we deplaned the passengers. Although the two flight attendants later reported they felt ok; they were pulled off of the trip. After block-in; I did a post-flight walk around and did not see anything out of the ordinary. We did fill out an online smoke; fume; and odor form and submitted it online. My understanding after talking with management is that a cabin recirculation fan had failed and a circuit breaker had popped and that was the reason for the smell of burning rubber. We did not know this at the time though. We need a better checklist for handling smoke; fumes; or odors as the current QRH seems to be all about eliminating smoke from a possible fire. Although we referenced it; I felt it was inadequate in determining what type of odor was occurring or how to respond appropriately in this situation.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.