IQAir filters are typically made from polystyrene. Polystyrene is a very environmentally unfriendly material (see Wikipedia). Our filters are framed in recyclable aluminium. Aluminium is the industry standard for HEPA/ULPA filters and is used world-wide in applications from hospital operating rooms to Class 1 clean rooms and pharmaceutical manufacturing and bio-safety laboratories, where cleanliness requirements are incredibly important. See here for information on aluminium recycling in Hong Kong.