Under normal temperature and pressure conditions, nitric acid (HNO3) is a colorless liquid with a suffocating odor detectable at extremely low concentrations. It is toxic by inhalation (H331), corrosive to the respiratory tract, and can cause severe chemical burns and eye damage. Classified as Category 1 by IARC * , there are links between chronic exposure to this substance and various forms of cancer.
*IARC: International Agency for Research on Cancer (part of the WHO World Health Organization)