The gas chambers were never sealed...or there was no provision to exhaust the gas from them... or there was no way for the guards to release the pellets into them, or....
As stated earlier, the extermination chambers were dynamited by the SS when they deserted the camp. There is therefore no direct evidence of what they looked like when they were in operation other than a few photographs taken by the Allies and the SS during the war (See Brugioni; Get ~/gifs/krema3.gif for view of Krema III taken during the war, from the air). The construction plans do include the air extraction systems, as one readily sees (in krema3.gif and others) and the air extraction system is mentioned in many documents. Some of the ventilation openings are still visible in the ruins of the gas chambers. The plans even include the shower heads that were placed in the gas chamber to mislead the victims.
It is a sad reflection on Leuchter's integrity and ability to use logic to see that he admits the Kremas were demolished, yet continues to claim he can deduce from their current state how they looked in 1944, before they were blown up! The following is a verbatim excerpt from his cross-examination by Mr. Pearson, in the Zündel trial:
Q. Crematoria III has been demolished.
A. Um, there are still parts of Crematoruim III there, but for the most part, the roof of the alleged gas chamber has crumbled and is all lying in bits and pieces in the basement of what would have been the alleged gas chamber.
Q. So, it's no longer subterranean?
A. That's correct. There's a hole in the ground.
Q. With respect to the gas chambers at Crematorium IV and V, those are totally demolished.
A. With the exception of the foundation, yes.
Q. So, all that was there for you to examine was the foundation of the building. Is that right?
A. That is correct.
Leuchter admits that the roof of the gas chamber of Krema III was all blown up and collapsed, and that Krema IV and V are gone except for the foundation! As for Krema II, his testimony is also intriguing:
Q. So, the gas chamber facility itself is presently underground?
A. Parts of it are and parts aren't.
Q. All right. And the parts that are underground, I take it that the roof is no longer whole; is that right?
A. Um, one of the roofs is broken into several pieces but it's essentially whole.
Q. It's broken in several pieces but it's essentially whole?
A. I mean it's not fragmented.
Q. How many pieces?
A. Three, I believe. I say that only to indicate that it's not fragmented. There are large slabs left of the roof.
Q. Right. And it's collapsed.
A. It's dropped several feet. It's partially collapsed.
Q. Is there dirt over it? Is it subterranean?
A. In some places there are dirt over it and some places there's no dirt.
Q. All right. And that's with respect to Crematorium II?
A. That's correct.
Even more incredible is to see what Leuchter writes in his report:
"Evidence as to Krema function is non-existent since Krema's I oven has been completely rebuilt, Kremas II and III are partially destroyed with components missing, and Kremas IV and V are gone".
"Are gone"! Yet, he can still conjecture about how they functioned before being destroyed...
The pictures of the gas chambers in their current state appear in Pressac. They are totally demolished and there is no way a reasonable person would claim to be able to conclude anything about how they functioned before they were destroyed.
Leuchter further ridicules himself by stating that the gas chambers were never sealed and that using cyanide gas inside them would be dangerous. But, he admits that the gas was used in them (for delousing purposes, as he claims). This is absurd, of course; if they were not sealed, introducing the gas into them would be dangerous no matter what the purpose was. This obvious contradiction alone is reason enough to discard the "Leuchter report"
http://www.nizkor.org/faqs/leuchter/leuchter-faq-11.html