They did board them up starting about 5 years ago, eventually doing them all. They recently started coming off again when they started taking out the window frames entirely. They just didn't bother putting the boards back up after.
Here's a video of them doing the final seal-up in the winter 2 years ago:
http://www.youtube.com/watch?v=ITAniU-1ZJI
After they did all of that, the interior conditions actually worsened considerably because the water damage had already been done over the past 10+ years that it sat unprotected and abandoned. With the windows sealed up, mold spores grew wild and the plaster seemed to come off the walls a lot faster. Might as well have just left the windows open, it was pointless by then. Even with all that in mind, the building is in fair condition considering how long it has been sitting like it has. It was built very well.