What smell was Lazarus afraid to death of in the Bible?

From the Gospel of John Chapter 11 verse 17 and specifically verses 38-39, Lazarus was already dead. Jesus, standing outside Lazarus' tomb, told the men to pull the tomb stone away (back then, a tomb was like a cave with a stone rolled in front of it). Lazarus's sister, Martha, exclaimed to Jesus that by now Lazarus's body would stink or smell because Lazarus had been dead 4 days. Back then, there was no embalming, so a dead body stank quickly as it decomposed. Bodies would let off gases during decomposition, so if the men removed the tombstone, anyone nearby would have been hit with those gases.