| # | Concept | Culture | Statement | Freq. |
|---|---|---|---|---|
| 1 | nitric oxide | air pollution | Nitric oxide is a pollutant emitted from vehicles and industrial activities, contributing to smog and acid rain. | 1 |
| 2 | nitric oxide | air pollution regulation | Nitric oxide is a harmful air pollutant, contributing to the formation of smog and acid rain, and is regulated by environmental agencies. | 1 |