The dioxide sulphur
(SO2) is formed by burning of solid and liquid combustible materials which contain
sulphur. It is a typical polluting of the urban and industrial
areas. The accumulation of this substance in the air is determined both by the density of
the settlements and by particular meteorological conditions. The most dangerous situations
happen in winter when the effect produced by the domestic heating
is added to the dioxide sulphur. In our region this polluting substance is practically
disappeared because the employed combustibles contain very low quantities of sulphur. In
the province of Terni, in particular, the dioxide sulphur
remains into low levels and is tending to decrease because the town has been supplied with
heating systems stoked by natural gas, which is not very polluting.

