Cardboard boxes, especially new ones, can emit formaldehyde due to the glue used in manufacturing. Accumulating these boxes may raise indoor air levels of this chemical, which is linked to serious health issues including cancer and respiratory diseases.
Cardboard boxes are a perfect home for cockroaches, offering them darkness to hide in and cardboard to feed on. Boxes can even bring cockroach eggs into your home, which may hatch unnoticed.
Storing piles of cardboard boxes and packaging materials creates a serious fire hazard and can block escape routes. If ignited, these materials can produce thick, toxic smoke very quickly, endangering everyone inside.