To reach Santa Catarina, the smoke from fires in the Amazon and Pantanal, spreading over at least ten states of the country until this Tuesday (20th), was carried by a wind system that also brings humidity from the north to the south of South America, forming what are called flying rivers.

But in the dry season, it is the smoke from the fires that has been transported through these corridors for thousands of kilometers. The situation will continue until the end of the week when a cold front could redirect this trajectory between different regions of the South and Southeast or even guide it back to the North — meaning the area affected by the smoke should still increase. In the latter case, the population of cities in Amazonas, Acre, and Rondônia could be affected by the smoke that will remain stored in the region. This was the case of Manaus, the capital of Amazonas, last year, which is also currently suffering from pollution haze caused by the fires.

This path begins with winds in the northern part of Brazil, which flow from east to west throughout the year, from the Atlantic Ocean to the continent. According to Marcelo Seluchi, general coordinator of Operations and Modeling at Cemaden (National Center for Monitoring and Natural Disaster Alerts), this route follows to the Andes Mountains, which act as a wall.

"The winds follow along the mountain range, turn in Acre, and pass through Rondônia, Bolivia, the Pantanal, and reach southern Brazil. That is the circuit," says the meteorologist. "Depending on the meteorological conditions, they are channeled to the South or Southeast region. It depends on how the cold fronts are positioned." Besides the position, the intensity of the fronts coming from the south, which carry moisture, can even reverse the smoke's path.