Air Pollution and Pepper
Pepper is very susceptible to peroxyacetyl nitrate (PAN). PAN usually affects the underside of newly matured leaves (Maynard and Hochmuth, 1997). The PAN injury is confined to only three or four rapidly expanding leaves of sensitive plants. Very young leaves and mature leaves are highly resistant. The area becomes bronzed, glazed or silvery in appearance. Pale green to white areas may also appear on the leaf surfaces. The only control measure is not to grow in areas known to have dangerous levels of air pollutants.
Peppers are also reported to be highly sensitive to sulphur dioxide and have an intermediate sensitivity to hydrogen sulphide. The sulphur dioxide symptoms can be characterized as acute injury by dead tissue between the veins or on leaf margins. Chronic injury is characterized by leaves with brownish-red or bleached areas. Young leaves seldom show damage. while fully expanded leaves are very sensitive to sulphur dioxide."