You can't possibly know that. Any chemical/biological weapons facilities are generally going to be kept secret, and wont be known to the general public.
But Russia somehow can, right? You see, for some reason they believe that they have information that such weapons are produced in Ukraine on the instructions of the United States. They have no evidence, no basis, but for some reason they believe that they have the right to threaten us with the use of such lethal weapons against Ukraine. The most interesting thing is that they definitely have such weapons, because they have used them many times, for example in Syria.