- (B) Peroxyacyl nitrates, or PANs, are powerful respiratory and eye irritants
present in photochemical smog. PANs are both toxic and irritating, as they
dissolve more readily in water than ozone. They cause eye irritation at
concentrations of only a few parts per billion. At higher concentrations they
cause extensive damage to vegetation. PANs are mutagenic and can be a
factor that causes skin cancer. PANs are classified as secondary pollutants as
they are not directly emitted as exhaust from power plants or internal-
combustion engines, but they are formed from other pollutants by chemical
reactions in the atmosphere. Since they dissociate quite slowly in the
atmosphere, PANs are able to transport NOx and other unstable compounds
far away from their urban and industrial origins and form tropospheric
ozone.
marvins-underground-k-12
(Marvins-Underground-K-12)
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