Smoke Alarm; December 1997; Scientific American Magazine; by Beardsley; 2 Page(s)

This past September, choking smoke from unchecked forest fires blanketed millions of square miles in southeast Asia. But that was not the only part of the world where burning of vegetation caused widespread haze. In the Amazon Basin the 1997 burning season produced a "very thick" pall that extended far beyond the region where smoke has spread in recent years, according to Paulo Artaxo of the University of S¿o Paulo. Forrest M. Mims III, an independent scientist who runs the Sun Photometer Atmospheric Network and is based in Seguin, Tex., says smoke may have covered half of Brazil when he was in the country in August. The blockage of sunlight, Mims believes, may encourage the spread of harmful bacteria and viruses.

Many of the fires in Brazil are set to clear the rain forest, although some take hold accidentally when farmers burn pasture, Artaxo states. One reason the 1997 fires were so extensive is that forests were very dry, a consequence of El Ni¿o, a periodic climatic oscillation, which is quite strong this year.