:yeahthat:
I know people use them because they are cheap and, unfortunately, petshops still sell them. But it's best to avoid using this, especially if you put bedding outside of a litterbox separated from the rest of the rabbit's living space (what I mean is that if your rabbit is free-ranged inside and that there is pine shaving just inside his litter box, it's not ideal but it will certainly be a lot less detrimental than for a rabbit cooped up in a cage in close quarter with the fumes and the dust for the major part of his days).
From what you said, your rabbit is kept outside? If he is, you have to isolate the hutch from the outside if it's not done already. Outside from that, hay is good to keep warm...