Recently smelled the air has a strange odor may be atrophic rhinitis, fungal sinusitis, chronic sinusitis, phantom smell and other causes. 1. Atrophic rhinitis: due to environmental factors stimulation, endocrine dysfunction or bacterial infection causes nasal mucosa atrophy, there may be a sense of smell loss, a large number of yellowish-green pus crusts and other manifestations. The nasal cavity with bacterial secretions and pus crusts contain protein decomposition can be dispersed together with the odor, so the patient may have recently smelled the air has a strange odor phenomenon. 2. Fungal sinusitis: Aspergillus, Candida, Trichophyton and other infections lead to specific infectious diseases. The structure of the nasal cavity of the patient is often damaged, necrosis, a large number of purulent crusts, etc., and then emit a foul odor, so the patient can smell the air has a strange odor phenomenon. 3. Chronic sinusitis: the main symptoms of nasal congestion, pus flow, decreased sense of smell, etc., the patient may feel that the nasal cavity has a bad smell or odor. 4. Phantom smell: also known as “olfactory hallucination”, when there is no corresponding olfactory stimulus, can smell a specific odor, causing unpleasant emotional experience. Commonly found in patients with psychiatric disorders. When there is a smell in the air, it is recommended to consult a hospital as soon as possible to find out the cause of the disease and actively treat it.