**4. Classification**

Following the SM exposure, acute and late (long term) complications may occur. The long term complications of SM exposure are much serious than acute effects .Generally the long term effects of SM exposure occur several years after a mild contact and are totally different from continuous longtime exposure (mainly occupational exposure) (12, 13).Several studies in Iran demonstrated that the most common late complication are respiratory problems, including chronic obstructive pulmonary disease (COPD), chronic bronchitis, bronchiolitis obliterans, bronchiectasis, airway hyperreactivity, and lung fibrosis (3-6).Ophthalmologic and cutenous problems are also seen in this period. Unfortunately, the respiratory problems usually exacerbate over time (12).A unique form of COPD known as" Mustard lung" is frequently seen as a long term complication (7).
