Question

What is the full form of PAN ?

Answer 1

Hint: PANs are both toxic and aggravating , as they dissolve more readily in water than ozone. They are lachrymators, causing eye irritation at concentrations of only a couple of parts per billion. At higher concentrations they cause extensive damage to vegetation. Both PANs and their chlorinated derivatives are said to be mutagenic, as they will be an element causing carcinoma .

Complete answer: Peroxyacyl nitrates are referred to as Acyl peroxy nitrates. APN or PANs are powerful respiratory and eye irritants present in photochemical smog. They are nitrates produced in the thermal equilibrium between organic peroxy radicals by the gas-phase oxidation of a variety of volatile organic compounds (VOCs), or by aldehydes and other oxygenated VOCs oxidizing in the presence of Nitrogen dioxide.
For example, peroxyacetyl nitrate, \[C{H_3}C{O_3}N{O_2}\]
\[Hydrocarbons{\text{ }} + {\text{ }}{O_2}{\text{ }} + {\text{ }}N{O_2}{\text{ }} + {\text{ }}light{\text{ }} \to {\text{ }}C{H_3}COOON{O_2}\]
The general equation is:
\[CxHy{O_3}{\text{ }} + {\text{ }}N{O_2}{\text{ }} \to {\text{ }}CxHy{O_3}N{O_2}\]
They are good markers for the source of VOCs as either biogenic or anthropogenic, which is beneficial within the study of worldwide and native effects of pollutants.
PANs are secondary pollutants, which suggests they're indirectly emitted as exhaust from power plants or combustion engines, but they're formed from other pollutants by chemical reactions in the atmosphere. Free radical reactions catalyzed by ultraviolet light from the sun oxidize unburned hydrocarbons to aldehydes, ketones, and dicarbonyl compounds, whose secondary reactions create peroxyacyl radicals, which combine with nitrogen dioxide to form peroxyacyl nitrates.
The most common peroxyacyl radical is peroxyacetyl, which may be formed from the radical oxidation of acetaldehyde, various ketones, or the photolysis of dicarbonyl compounds like methylglyoxal or diacetyl.

Note:
Since they dissociate quite slowly within the atmosphere into radicals and Nitrogen dioxide, PANs are ready to transport these unstable compounds distant from the urban and industrial origin. This is important for tropospheric ozone production as PANs transport Nitrogen oxide to regions where it can more efficiently produce ozone.