关于极淡浓度NO_2气体毒性的意见不一。拿面孔作实验,如在18个月内每天暴露於含NO_210—12ml/m~3(20mg—40mg/m~3)的空气中,或最大浓度变异由5—30ml/m~3(10mg—60mg/m~3)中6—8小时,并无何种病象显出。另一方面,如果经常暴露於浓度5mg/m~3之有毒NO_2中约3—5年,却将引起蛀牙、气肿病及其他心跳(?)滞现象。据专家意见,NO_2所许可的最 Opinions were divided on the toxicity of NO 2 gas at very light concentrations. Take the face for experiments, such as daily exposure to air containing NO_210-12ml / m ~ 3 (20mg-40mg / m ~ 3) within 18 months, or the maximum concentration variation from 5-30ml / m ~ 3 60mg / m ~ 3) 6-8 hours, and no signs of any disease. On the other hand, frequent exposure to toxic NO 2 at a concentration of 5 mg / m 3 for about 3-5 years can cause cavities, emphysematosis and other signs of heartbeat. According to expert opinion, NO_2 is the most permitted