Shown here are the chemical formula for peroxyacytyl nitrate (PAN) and a diagram chemists use to represent the structure of this molecule. Note the structure based on nitrogen dioxide (NO2) in the lower right segment of the PAN molecule.
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Windows to the Universe original artwork by Randy Russell.

PAN (Peroxyacytyl nitrate) - C2H3O5N

PAN (Peroxyacytyl nitrate) is a toxic chemical that is an important component of smog. PAN is a gas at normal temperatures and pressures. Its chemical formula is C2H3O5N. PAN molecules are composed of carbon, hydrogen, oxygen, and nitrogen atoms.

PAN forms via the combination of other compounds in the presence of sunlight. One component of PAN is nitrogen dioxide (NO2), which comes from the exhausts of fossil fuel-burning cars and trucks, coal-burning power plants, and other industrial processes. Volatile Organic Compounds (VOCs), released to the air as fumes from gasoline, paint, solvents, and pesticides, comprise a second set of ingredients that go into the making of PAN. A series of reactions transform VOCs into other compounds. These compounds then combine with oxygen and nitrogen dioxide to form PAN. Energy from sunlight helps drive these chemical reactions via a process called photodissociation. Ozone and airborne particulates are released as byproducts during the creation of PAN.

PAN is highly reactive and is a strong oxidizing agent. It is a powerful eye irritant and is also harmful to the respiratory system. At high concentrations it is quite damaging to plant materials, which it "burns" in a chemical reaction akin to slow-motion combustion.

Last modified February 16, 2006 by Randy Russell.

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