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September 20, 2026 NC State

Diagram showing the atmospheric cycling of nitrogen oxides. Emissions from vehicles and industrial sources release NOₓ. Nitric oxide (NO) and nitrogen dioxide (NO₂) interconvert through reactions involving ozone, sunlight, and radical species. Additional inorganic products such as nitric acid and organic products such as peroxyacetyl nitrate are formed. Some compounds undergo long-range atmospheric transport, while others are removed through deposition to land and surfaces. The diagram illustrates how emissions, atmospheric chemistry, transport, and deposition affect ambient NO₂ concentrations and exposure.

Why Independent Scientific Review Matters for EPA’s Nitrogen Dioxide Air Quality Standard

By frey The U.S. Environmental Protection Agency (EPA) is reviewing the national air quality standard for nitrogen dioxide (NO₂), a common air pollutant produced by combustion. People...