For Feature X08: Materials Optimization, prioritizing materials with enhanced chemical restrictions is crucial. Ceiling tiles with a Health Product Declaration (HPD) published in the HPD Public Repository indicate a high level of transparency regarding the chemical composition and potential health hazards of the materials used. This transparency is key in the WELL Building Standard's approach to materials optimization, as it allows for informed decisions to be made about the selection of materials that minimize negative health impacts. Products with HPDs contribute to a healthier indoor environment by ensuring that materials with potentially harmful chemical emissions are avoided.