Nitrogen oxides, particularly nitrogen dioxide (NO₂), have harmful environmental effects, primarily impacting plant life and contributing to acid rain.
Effects on Vegetation
Nitrogen dioxide can be directly harmful to plants. According to the Ministry for the Environment environment.govt.nz, nitrogen dioxide is toxic to plants when present in short-term concentrations of 120 µg/m³ or higher.
- Reduced Plant Growth: Exposure to these levels of NO₂ can significantly reduce plant growth.
- Synergistic Effects: The negative impacts on vegetation are even worse when nitrogen dioxide is present along with other air pollutants like sulfur dioxide (SO₂) and ozone (O₃).
Contribution to Acid Rain
Nitrogen dioxide plays a key role in the formation of acid rain.
- Acid Formation: Along with sulfur dioxide, nitrogen dioxide reacts in the atmosphere with water, oxygen, and other chemicals to form acidic compounds.
- Impacts: These acidic compounds then fall to Earth as acid rain, fog, snow, or even dry particles, damaging forests, lakes, streams, buildings, and other structures.
In summary, the primary harmful environmental effects of nitrogen oxides, as highlighted by the reference, include direct toxicity and growth reduction in plants, exacerbated when other pollutants are present, and their contribution to the formation of acid rain.
