If the air contains more acids than bases (alkalies), then rain will probably have an acidic constitution. That's what is happening today. Because there are not enough bases in the air to neutralize the acids, we have acid rain. But for years, researchers have concentrated on the acid factor and ignored the base factor in seeking a cause and solution for the acid rain problem.
ONLY A SPRINKLING OF ACID RAIN IN THE 1950s
In the 1940s and 1950s, there wasn't much acid rain. The concentrations of acids and alkalies (bases) in the environment were better balanced. At the time, cement plants spewed more than 10 million tons of portland cement kiln dust into the air each year. A strong base, this cement dust probably neutralized as much as 25 percent of the acidic matter in the air over the United States. The so-called pollutants from the cement plants actually cleaned up the air. But the Public Health Service and the Environmental Protection Agency mistakenly thought the dust contained lead. That and the nuisance of dust fallout near the plants led them to make rules that virtually eliminated these emissions. This sudden absence of cement dust in the air may be part of our current acid rain problem.