In 2012, administrative assistants averaged $33,560 a year, according to the Bureau of Labor Statistics. But this figure accounts for all administrative support, regardless of employer.Those working for dental offices averaged closer to $35,020.With training as a medical secretary, administrators working in dental offices can expect even higher salaries, at an average of $36,960.hose working for dental offices averaged closer to $35,020. With training as a medical secretary, administrators working in dental offices can expect even higher salaries, at an average of $36,960.
Human Sources of Sulfur Oxides; Wood Smoke; Contributors; It has been estimated that on a global basis, natural sources, such as volcanoes, contribute about as the same amount of sulfur oxides to the atmosphere as human industrial activities. This amounts to 75-100 million tons from each source per year. However, in industrial countries such as in Europe and North America, human activities contribute 95 % of the sulfur oxides and natural sources only 5 %. In the Western States, natural sources of sulfur oxides may be more important.
Causes of Acid Rain. Both natural and man-made sources are known to play a role in the formation of acid rain. But, it is mainly caused by combustion of fossil fuels which results in emissions of sulfur dioxide (SO 2) and nitrogen oxides (NO x).an-made sources include emission of sulfur dioxide and nitrogen oxides due to combustion of fossil fuels. Roughly two-thirds of all sulfur dioxide and one-fourth of all nitrogen oxides come from generation of electricity through burning of fossil fuels such as coal.