Record-breaking fires engulf South America, bringing black rain, green rivers and toxic air to the continent

South America is experiencing record-breaking fires, which have led to "black rain," green rivers and hazardous air pollution almost 50 times higher than the level recommended by the World Health Organization, according to the air quality monitoring company IQair.

Between Jan. 1 and Sept. 16, the continent recorded 364,485 forest fires, surpassing the 2007 record of 345,322 fires, according to data from the Brazilian Space Research Institute and Reuters.

The historic drought in the Amazon has worsened the spread of the fires. Many of the fires have been attributed to human activity, but the drought has created favorable conditions for their rapid spread. As a result, 60% of Brazil's territory is currently affected by smoke.

Including neighboring countries and the Atlantic Ocean, the area impacted by the toxic cloud now spans 4 million square miles (10 million square kilometers) — an area larger than the entire United States.

"The air quality in Brazil has never been worse," Alessandra Fidelis, a researcher at the Plant Ecology Laboratory of the State University of São Paulo, told Live Science.

Natalia Gil, an atmospheric Science expert and member of the Air Quality and Emissions Department at the Technological Laboratory of Uruguay, told Live Science there has been a progressive decline in air quality in cities across southern Brazil, northern Argentina, Bolivia, Paraguay and northeastern Uruguay.

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