Proofing Heating Pipe Passage Way
It will very hard to prevent the odor of tobacco smoke from getting into your flat. I would not attempt to renew with that seal, you could make it worse.
That wool could be anything from steel wool to copper wool to other fibers that you definitely don't want to do anything to. You don't want to disrupt it.

You could put some duct tape over the existing seal, but even that could cause problems. If any tape you placed there were later pulled off, it could pull apart the existing seal.