Some patients with smog are found incidentally during physical examinations or other tests and are asymptomatic; typical symptoms in some symptomatic patients with smog include one or a combination of one or more of transient ischaemic attack (TIA) (headache, seizures, limb weakness, sensory abnormalities and changes in vision and visual field), cerebral infarction (patients have varying degrees of limb movement or sensory impairment, visual field deficits, aphasia, etc.), and cerebral haemorrhage (headache, vomiting, impaired consciousness, etc.).