SP City May Have Black Rain Caused by Smoke from Pantanal and Inland Fires This Week | Saint Paul

The occurrence of the phenomenon, however, depends on the amount of particulate material brought by the winds that blow from the interior of the country to the southeast. Last weekend, the dark-colored rain occurred in the Rio Grande do Sul regions.

In addition to the possibility of dark rain, there is also the possibility that the sky turns orange during the day.

In the case of São Paulo, the soot that can reach the capital must come not only from the fire that hits the Pantanal, but also from the fires that occur in the interior of the state, explains Alexandre Galvão, a meteorologist at Climatempo.

This year, fire outbreaks in SP more than doubled, compared to 2019. The increase occurred especially in the months of August and September.

The expectation is that a cold front from the south of the country will reach the state of São Paulo on Friday (18), bringing the possibility of rain towards the end of the afternoon. There is also a rain forecast for Saturday afternoon (19) and for all of Sunday (20), when temperatures should drop and the blows should be stronger.

“The rain always washes the atmosphere, removes dust, pollution, possible soot, any particulate material that is in the atmosphere. So the probability of dark rain is higher in the first rain forecast”, explains meteorologist Alexandre Galvão.

Soot travels higher than the particulate matter of common pollution and can be absorbed by the cloud, giving rise to black clouds that attract attention in the skies of large cities, according to Theotonio Pauliquevis, a physicist and professor at the Federal University of São. Paulo (Unifesp).

“Rain clouds are 1.5 km to 10 km above the ground. When pollution starts at surface level and comes from cars or factories, it gets trapped under the clouds, forming a visible, darker layer on the ground. horizon, “he explains. “So when the water falls, it hits the particles and the flooding leads to this common pollution.”

“The smoke cloud, on the other hand, travels about 3 or 4 km from the ground. It collides head-on with the rain cloud, which absorbs the soot and forms this type of viscous substance that gives rise to dark reddish clouds and also rain. ‘black’, darker than normal ”, says the researcher, who studies the chemical composition of rain in the Amazon during burning periods.

On August 19, 2019, the phenomenon of black rain occurred in the city of São Paulo due to the fires that occurred in the Amazon.

Technical analyzes from two universities showed that dark-colored rainwater collected by residents of the capital contained particles from the burning. On social media, residents of Greater São Paulo posted images of dark rainwater.

The test carried out by the Institute of Chemistry of the University of São Paulo (USP) identified the presence of retention, a substance derived from the burning of biomass and considered a marker of burning, in the rainwater collected on Monday.

The examination carried out by the Municipal University of São Caetano (USCS) showed that the concentration of particulate matter, that is, soot, was seven times higher than that registered in normal rainwater.

While USP researchers looked at retention identification, which is a fire marker, the USCS analysis found 7 times the normal amount of soot and the presence of sulfides 10 times the average. The substance comes from the burning of fossil fuels and fires.

“If I have 7 times more than I should have, I have chemicals in this water that can affect health. Now we are going to have to investigate what that is,” says Marta Marcondes, biologist and professor of the research line. USCS Health and Environment.

Marcos Buckeridge, director of the Institute of Biosciences at the University of São Paulo (IB-USP), says that the soot from burning can also contain substances toxic to humans. “If we had received smoke over the city, without the presence of a cold front that brought rain, this could have a much worse effect on people,” he says.

GloboNews film reporter Leandro Matozo collected sooty water in buckets in the backyard of the house where he lives, in São Mateus, on the east side of the capital. Samples collected at the site were used in university examinations.