Peroxyacetyl nitrate is a peroxyacyl nitrate

Peroxyacyl nitrates

Acyl peroxy nitrates, or Peroxyacyl nitrates , are powerful respiratory and eye irritants present in photochemical smog. They are produced by the gas-phase oxidation of a variety of volatile organic compounds , or by aldehydes and other oxygenated VOCs oxidizing in the presence of NO2...

. It is a secondary pollutant

Pollutant

A pollutant is a waste material that pollutes air, water or soil, and is the cause of pollution.Three factors determine the severity of a pollutant: its chemical nature, its concentration and its persistence. Some pollutants are biodegradable and therefore will not persist in the environment in the...

 present in photochemical smog. It is thermally unstable and decomposes into peroxyethanoyl radical and nitrogen dioxide

Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the formula it is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent...

 gas. It is a lachrymatory substance.

Peroxyacetyl nitrate, or PAN, is an oxidant more stable than ozone

Ozone

Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

. Hence, it has capabilities of long-range transport greater than that of ozone. It serves as a carrier for oxides of nitrogen (NOx) into rural regions and causes ozone formation in the global troposphere.

The formation of PAN on a secondary scale becomes an issue when ethanol is used as an automotive fuel.