Science / Medicine : Dust From Drought Is Curse and Blessing

The dust stirred up by drought conditions may sometimes help neutralize acid rain, but it can also form other harmful chemical products in the atmosphere, scientists reported last week. Dale Gillette of the National Oceanic and Atmospheric Administration said studies have found that dry, windy drought conditions--like those that affected large regions of the United States last summer--increase the amount of dust in the atmosphere.

Dust from roads is usually high in calcium and low in clays, and if such dust rises high enough into the atmosphere, its alkaline content can neutralize the precursors of acid rain, said Gillette. However, a different scenario apparently takes place with dust blown off fields. Gillette said such dust is lower in alkalines and often contains clays that can be dissolved by acidic compounds in the atmosphere, releasing soluble aluminum and other toxic metals.

In the West, the NOAA researcher said he found dust-related toxic chemicals to be highly prevalent in the air, and claimed their levels were comparable to sulfur dioxide emissions from major air pollution sources.