The problem is VOCs, volatile organic compounds that evaporate from all organic materials (i.e. everything but metal, stone, ceramics, glass). Either immediately or during the aging process as a result of the decomposition processes of the individual components. Adhesives are particularly susceptible to decomposition processes, but so are plasticizers. For example, formaldehyde was once a big problem for chipboard.
The higher its proportion in the room air, the more harmful it is to your health. The smaller and closer to the floor the occupants are, the more of these substances are absorbed and accumulated in the body. And new buildings emit not just one new element, but hundreds. From cable sheathing to paints, upholstery, sealants, plaster and insulation materials, to new furniture and doors.
No manufacturer tests the harmlessness of the aging processes of their materials. If a material becomes brittle, breaks, swells quickly, changes color, it means it has reached the end of its useful life and can no longer perform its function, but these processes take several years.