They occur mainly in the form of sulphur dioxide. It is produced in large quantity during smelting of metallic ores and burning of petroleum and coal in industries, thermal plants, home and motor vehicles. In the air, SO 2 combines with water to form sulphurous acid (H 2 SO 3 ) which is the cause of acid rain. It causes chlorosis and necrosis of vegetation. Sulphur dioxide, above 1 ppm, affects human beings. It causes irritation to eyes and injury to respiratory tract. It results in discolouration and deterioration of buildings, sculptures, painted surfaces, fabrics, paper, leather, etc.
For the most part, colonial and Soviet satellite societies were repressive and undemocratic in nature. Domestic governmental systems and structures were controlled and operated either from abroad or by a select domestic, privileged group. Consequently, when liberation came, these states lacked the internal structures, institutions, and 1egalitarian way of thinking needed to create good governance systems. The result is that many postcolonial and post-Soviet states, although independent, are still ruled by repressive and restrictive regimes. For example, Melber (2002) states, "(t)he social transformation processes in Zimbabwe, Namibia, and South Africa can at best be characterized as a transition from controlled change to changed control."