HazMat Management

Peroxyacetyl Nitrate (PAN)

CAS Number: 2278-22-0Molecular Weight = 121.06Peroxyacetyl nitrate (PAN) is a component of photochemical smog, which is a mixture of air pollutants that includes both gases and particulates, some of w...

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April 1, 2003 by Ron Brecher, Ph.D.

CAS Number: 2278-22-0

Molecular Weight = 121.06

Peroxyacetyl nitrate (PAN) is a component of photochemical smog, which is a mixture of air pollutants that includes both gases and particulates, some of which react with sunlight.

Toxicity summary

Acute effects — Low-levels of PAN do not have an effect on either lung capacity or respiratory rate in humans. However, when PAN is inhaled along with ozone, as it often is in normal air, lung capacity decreases and respiratory rate increases. PAN may also cause eye irritation. Toxicity studies in rats and mice have shown that PAN may cause emphysema, impaired breathing, acute pulmonary edema or lung lesions following inhalation exposure.

Chronic effects — No studies were found on the effects of chronic PAN exposure in humans. However, rats exposed to PAN for 13 weeks demonstrated signs of abnormal behaviour, increased lung weights, weight loss, depressed growth, respiratory irritation and mortality.

Genotoxicity and mutagenicity — PAN has been determined to be a weak point mutagen and a clastogen. Although positive results have been observed in various bacterial mutagenicity assays both in the presence and absence of metabolic activation negative results have been observed in animal studies.

Sensitive populations — Individuals with heart and lung disease, the elderly or small children may be more sensitive to the effects of PAN and smog exposure.

Ronald Brecher, Ph.D. is a founding partner of GLOBALTOX International Consultants Inc., with offices in Guelph, Ontario; Seattle, Washington; and, Portland, Oregon. Contributing authors: Karen Phillips and Stacie France. E-mail Ron at rbrecher@globaltox.ca

Chemical formula C2H3NO5

Synonyms PAN, Peroxyacetic Nitric Anhydride, Nitric acid anhydride with peroxyacetic acid.

Physico-chemical PAN exists in the atmosphere as a gas. properties

Environmental In the atmosphere, PAN has a lifetime of about three fatemonths. It degrades by photolysis or by reacting with hydroxyl radicals in the air. Carbon monoxide, carbon dioxide, nitromethane and oxygen are some of the products of the thermal decomposition of PAN. Dry deposition of PAN on soil and grass at night also decreases its lifetime in the atmosphere. PAN is highly stable in colder regions. In warmer parts PAN degrades and releases nitrogen oxide.

Environmental PAN inhibits photosynthesis in various types of plants. impactExposure to high levels of PAN may also cause other effects on plants, including alterations in leaf colour.

SourcesPAN is formed when sunlight energy causes non-methane hydrocarbons and nitrogen oxides to react. Acetaldehyde, methylglyoxal, and various byproducts of the oxidation of aromatic compounds are all precursors to PAN. Sources of hydrocarbons and nitrogen oxides include vehicle emissions, tobacco smoke and the burning of petroleum products, such as coal and natural gas.

ExposureHuman exposure to PAN occurs mainly around large urban centers where emissions of precursor pollutants from motorized vehicles and industrial sources are high. PAN is a component of photochemical smog, whose formation peaks in intensity around midday when the sunlight is strongest. Concentrations of PAN also increase with altitude and latitude.

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5 Comments » for Peroxyacetyl Nitrate (PAN)
  1. Angie Saldana says:

    What is the answer of molecular formula of peroxyacylinitrate (PAN) one of the components of smog and is a compound of C,H,N,O with percent composition by mass:19.8% C, 2.5% H, 11.6%N. given that its molar mass is about 120g? I nned asap.

  2. MENIA says:


  3. saranya says:

    Nice explanation about PAN. Which is so useful for me.

  4. Nagma Alam says:

    very effective article.

  5. Tam Nguyen says:

    A Gas Mask can filter out Tear Gas so what filter can out Peroxyacetyl Nitrate (PAN)? Activated Carbon HEPA filter? Is its molecule size too small for any kind of air filter?

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