To confirm a direct relationship between quantities of air pollution and vegetation, researchers from University of São Paulo (USP) and São Paulo State University (UNESP) studied jataí bees (Tetragonisca angustula) as environmental quality bioindicators.

The findings point to the need to create ecological corridors that will connect separate landscapes and add to the growing scientific evidence of the importance of afforestation in urban areas.

Native bees in Brazil’s São Paulo state are suffering from human-caused air pollution, but plants help ameliorate those effects, according to a new study.

The study found that plants act as filters and as protective barriers. The larger the green area, the lower the pollutants in the environment ​​and in the bees. These findings have important implications, since bees are the main pollinators in the animal kingdom, pollinating 75% of all global farmed plants.

The study measured accumulated levels of 21 chemical elements in the tissues of jataí bees, collected in eight areas in São Paulo state in remnants of the Atlantic Forest where forest cover was 16-70% with varying levels of human activity, like agriculture, roads, cities, industries, pastures, and degraded land.

Marcela de Matos Barbosa, an entomologist at USP was the author of the study. He said that what distinguished their work was that their bioindicators were a group of bees that had not been studied on a global scale and are widely distributed in Brazil in urban and preserved areas.

Barbosa said that bees can carry fine particles of atmospheric aerosols from surrounding pollution when they fly through different environments to collect pollen.

This unrelated 0:40-second video by SassePhoto shows these unusual and exotic jatai bees found in Brazil:



Bees that live in more forested areas have lower levels of mercury, copper, cadmium, and chromium in their bodies, according to the study. The main source for heavy metals cadmium and chromium are the agrochemicals used on farms.

The study shows how land uses influence the presence of pollutants found in bees. Where there are roads, the bees accumulate chromium, mercury, aluminum, uranium, arsenic, lead, and platinum in their bodies. The main pollutants in areas with degraded soil or pastures are zinc, cadmium, manganese, magnesium, barium, and strontium.

These findings add to a body of evidence about the importance of urban ecological corridors, or mitigation projects like afforestation in urban areas, said study coordinator Milton Cezar Ribeiro, a professor at UNESP’s Biosciences Institute.

Urban ecology is a field that has been growing recently in academia. It addresses the creation of urban ecological corridors from an ecological and socio-environmental perspective, according to Ribeiro.

This unrelated 0:51-second video by Washington Ferraz shows how these remarkable jatai bees enter their hives:



They created a tool to simulate best scenarios within a human and non-human context, said Ribeiro, where certain plant groups are selected according to routes that connect the mid-city to the outskirts. Taking care of landscapes separately, without connecting them, isn’t enough. Planting trees in the streets is as vital as encouraging the use of vegetation in houses, buildings and even on walls.

It is also important to select the right plant species to create urban ecological corridors, said Giuliano Locosselli, a biologist at the USP Biosciences Institute and author of a pioneering study published in 2019 that showed how pollution in the city of São Paulo impacts tree growth.

Some trees are more resistant to pollution than others. Now we must know which is which as we try to answer this question within a larger project that is part of an international consortium focused on nature-based solutions, to help decision-makers build more efficient and resilient urban forests.

Public policies and law enforcement have been major obstacles to progress on this front. In the city of São Paulo, a law proposed in 2009 mandated that the entire public bus fleet running on diesel switch to clean fuels by 2018. This has not been enforced to date, and diesel emissions are responsible for almost 95% now of particulate matter — the most toxic pollutant to human health.

This is why air pollution is today the world’s top cause of illness and death from chronic non-communicable diseases. It causes 40% of heart attack deaths and 50% of pneumonia cases in children. Air pollution is considered the top cause of infant mortality and causes 6% of lung cancer cases.

Former technical director of the microbiology laboratory at USP’s medical school and founder and director of Instituto Saúde e Sustentabilidade (Institute of Health and Sustainability), Evangelina Vormittag finds these figures an unfolding tragedy. The government lacks political will to make changes.

She believes Brazil needs governments with strength and courage to make necessary changes, which requires confronting economic forces. There is a 20-plus-year-old law that mandates vehicle inspection throughout Brazil. States must comply with it, but no state does. There is no sanction.

Her institute, along with over 20 other organizations under the Coalizão Respirar (Breathe Coalition), filed a lawsuit challenging the constitutionality of the criteria adopted by Brazil’s National Council for the Environment (CONAMA) for establishing air quality standards.

The World Health Organization (WHO) has determined concentration levels of pollutants that are safe for health since 2005, she said. In 2021 the levels Brazil considers legal are three times higher than what the WHO recommends. States that are responsible for managing air quality are allowed to pollute three times more. The air is polluted, and they say it is normal. Nobody warns the people about it.

None of the nine states making up the Brazilian Amazon monitors their air quality, said Vormittag, who sees this failure as catastrophic. In the Amazon there is neither measurement nor assessment, she said. If there was any monitoring, it would be a scandal. The levels of pollution by particulate matter, as found in areas with fires, are like those in China.