Since we're most likely using different versions of the book, giving you a page number may not be helpful. In my version the quote I'm about to give is on page 49, about three-quarters of the way through Part 1. I would suggest you look for the quote in my referenced link below, and find the corresponding page number in your own book.
"Some of the best ever."
"Oh, you know, the bunch."
"Yes, the bunch, the bunch, the bunch." He pressed at the pain in his eyes and suddenly the odour of kerosene made him vomit.
This passage takes place shortly after Montag and the other firemen had sacked the old woman's house, preparing to ignite it, except that the woman started the fire herself and burned along with the house and the books. Montag is still feeling a great deal of emotional turmoil over this (as well as the fact that he stole a book from her home and is now hiding it in his own) and Mildred is up to her usual obliviousness, which further antagonizes Montag. I don't think the smell of kerosene is what actually upsets him, but rather the memories and guilt associated with burning the old woman. This is also in direct contrast to Montag's earlier self-characterization; during his first meeting with Clarisse, he says kerosene is "nothing but perfume" to him. This might indicate a significant shift in his character.