Atmospheric dust may be part of the answer. For the past several decades, scientists have been studying acid rain and how it affects the environment. As the harmful consequences of acidic air pollutants became increasingly clear, governments in North America and Europe began to regulate emissions of these compounds. In some respects, the issue seemed wrapped up. But the problem of acid rain has not gone away.
Recent findings suggest that acid rain is a much more complex phenomenon than previously thought.
Results from several studies point to the unexpected but critical role of chemicals in the atmosphere known as bases, which can counteract the effects of acid rain by neutralizing acidic pollutants. We have found that all the attention given to acidic compounds in the atmosphere has obscured the fact that emissions of bases have also decreased. A number of factors seem to be diminishing the level of these atmospheric bases and in the process aggravating the ecological effects of acid rain. Ironically, among these factors are some of the very steps that governments have taken to improve air quality. Most of the bases in the atmosphere can be found in airborne particles referred to as atmospheric dust.