Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
Nitric oxide is a colorless gas that forms when nitrogen and oxygen react at high temperatures, such as in car engines or power plants. It plays a role in the formation of smog and contributes to air pollution.
Related terms
Nitrogen dioxide (NO2): Nitrogen dioxide is a reddish-brown gas that forms when nitric oxide reacts with oxygen in the atmosphere. It is also a component of smog.
Sulfur dioxide (SO2): Sulfur dioxide is a colorless gas that is released into the air when fossil fuels containing sulfur are burned. It contributes to acid rain and respiratory issues.
Smog refers to a type of air pollution that occurs when pollutants, such as nitric oxide and nitrogen dioxide, react with sunlight. It often appears as a hazy layer over cities and can have harmful effects on human health.