page_title: Nitrogen dioxide
section_title: Toxicity
hierarchical_section_title: Nitrogen dioxide / Toxicity
caption_attribution_description: English: Nitrogen dioxide diffusion tube for air quality monitoring. Positioned in the City of London.
context_page_description: Nitrogen dioxide is a chemical compound with the formula NO
  ₂. It is one of several nitrogen oxides. NO
  ₂ is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year for use primarily in the production of fertilizers. At higher temperatures it is a reddish-brown gas. Nitrogen dioxide is a paramagnetic, bent molecule with C₂ᵥ point group symmetry.
context_section_description: Gaseous NO
  ₂ diffuses into the epithelial lining fluid (ELF) of the respiratory epithelium and dissolves, and chemically reacts with antioxidant and lipid molecules in the ELF; the health effects of NO
  ₂ are caused by the reaction products or their metabolites, which are reactive nitrogen species and reactive oxygen species that can drive bronchoconstriction, inflammation, reduced immune response, and may have effects on the heart. 
  Acute harm due to NO
  ₂ exposure is only likely to arise in occupational settings. Direct exposure to the skin can cause irritations and burns. Only very high concentrations of the gaseous form cause immediate distress: 100–200 ppm can cause mild irritation of the nose and throat, 250–500 ppm can cause edema, leading to bronchitis or pneumonia, and levels above 1000 ppm can cause death due to asphyxiation from fluid in the lungs. There are often no symptoms at the time of exposure other than transient cough, fatigue or nausea, but over hours inflammation in the lungs causes edema.
  For skin or eye exposure, the affected area is flushed with saline. For inhalation, oxygen is administered, bronchodilators may be administered, and if there are signs of methemoglobinemia, a condition that arises when nitrogen-based compounds affect the hemoglobin in red blood cells, methylene blue may be administered.
  It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and it is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.
caption: Nitrogen dioxide diffusion tube for air quality monitoring. Positioned in the City of London
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