>>1551581You don't. If you're feeling particulate matter on your fingers after handling the book, unless that is external sourced dust, which is extremely unlikely to be present in in the middle of a book since they are usually stored closed , it's the book itself disintegrating.
If it's worth it, you can try calling a conservator.
>>1551599>they use an ozone machineNo, they don't. That's the exact opposite of what they do. The yellowing of paper is usually the result of lignin in the paper oxidising. Ozone is a strong oxidant. Putting ozone on the paper will make the lignin oxidise more. More damage to the book, more loss of strength in the book, and more yellowing.