What is – It 'a colorless, pungent odor of natural product of the oxidation of sulfur. The main emissions of sulfur dioxide resulting from combustion processes that use fossil fuels like (diesel, fuel oil, coal) in which the sulfur is present as impurities, and metallurgical processes. A very low percentage of sulfur dioxide in the air (6-7%) comes from vehicular traffic, particularly from diesel vehicles. The concentration of sulfur dioxide has a very noticeable seasonal variation, with the maximum values in the season, where they are in function of the domestic heating systems.
Method of measurement – The Sulfur dioxide is measured with a fluorescence method. The air to be analyzed is placed in a special chamber in which are sent to UV radiation 230-190 mm. This radiation excites the SO2 molecules that present, stabilizing, emit radiation in the visible spectrum measured with a suitable detector. The 'light intensity is a function of the concentration of SO2 in the air. The unit of measure by which they are measured concentrations of sulfur dioxide is the microgram per cubic meter (µg/m3).
Damage caused – L 'SO2 is very irritating to eyes, throat and respiratory system: It also amplifies its toxic effects in the presence of fog, as it is easily soluble in the small water droplets. The more tiny droplets can reach deep into the lungs causing bronchoconstriction, acute bronchitis and bronchial irritation. Also in atmosphere, through reactions with oxygen and water molecules, Because the so-called "acid rain", rainfall with a significant acid component, responsible for damages to roofs and monuments wooded with toxic effects on plants and acidification of water bodies, in particular to weak parts, with consequent impairment of aquatic life.
Evolution - The Sulfur dioxide was considered, until a few years ago, the main air pollution, however, today the progressive improvement of fuel quality(lower sulfur content in refinery products, imposed by D.P.C.M. the 14 november 1995) together with the increasingly widespread use of natural gas have decreased significantly the presence of SO2 in the air.
