Anosmia is the temporary or permanent complete loss of ability to perceive odour. Temporary anosmia can be caused by infection or nasal blockage. Permanent anosmia may be due to damage to olfactory nerve damage or brain damage. A person may have anosmia for one particular smell referred to as specific anosmia. If an assessor is noticed to detect odours during analysis but is not detecting a specific odour this may be specific anosmia.