Although CNTs are one of the most commonly engineered nanomaterials, previous studies have shown pristine or unmodified carbon nanotubes can cause pulmonary fibrosis/lung scarring and lung inflammation in animals and cellular models after inhalation exposure in a similar way as asbestos. The team used atomic layer deposition to coat the CNTs with a thin film of aluminum oxide, before exposing the mice to a single dose through inhalation. Although the coating wasn’t able to eliminate the health risks from multi-walled CNTs, it was shown to reduce problems such as pulmonary fibrosis.