In samples taken on board CASA C-212 Aviocar aircraft of the National Institute of Aerospace Technology of Spain (INTA) with the operational support of the 47 Joint Group of the Air Force, we have found concentrations equivalent to one billion microplastics in the sky of Madrid .
The trajectory calculations indicate that some of these particles can travel hundreds or thousands of kilometers before being deposited. This is the first study in which the presence of microplastics in the atmosphere at high altitude is directly demonstrated.
What are microplastics?
Microplastics are small pieces of plastic that generally come from the disintegration of larger objects and that have become sadly famous on our coasts. They can be relatively large (5mm), or as small as one micron, which is the size of a bacterium. They can also be fibers. In fact, synthetic clothing is an inexhaustible source of tiny polyester or acrylic fibers, which are also microplastics.
A material closely related to microplastics is man-made fibers. These are natural materials, such as cellulose, cotton or wool, which have undergone industrial processes that make them strange to the environment. The risk in this case comes from its content in artificial chemicals, such as fabric softeners or colorants.
Microplastics are found everywhere, not just in the oceans where they form the well-known islands of garbage. Our treatment plants discharge huge amounts of microplastics that reach rivers and agricultural soils.
Microplastics have also been found in remote locations. Recently, our team has identified microplastics in a seasonal stream in a specially protected area of Antarctica (ASPA-126) where access has been strictly regulated since 1966.
Microplastics in the air
Naturally, there are also microplastics in the air. Although the atmosphere is a much less studied medium, it is known that concentrations in urban environments reach the values of some microplastics per cubic meter. These concentrations can be much higher in closed environments, where exposure to them is increased by inhalation.
Available data indicate atmospheric deposition rates of several hundred microplastics per square meter per day, even in alpine environments relatively remote from large population centers. These data suggest that microplastics can reach considerable heights and be carried long distances by high winds.
However, until now the presence of microplastics has never been determined beyond a few meters above ground level.
A pioneering sampling
Thanks to the support of the 47 Joint Group of the Air Force, our team, belonging to the Thematic Network of Micro and Nanoplastics in the Environment, has been able to carry out direct samples on board INTA airplanes.
The samples were taken between 1500 and 2500 m above ground level, flying over the towns of Madrid, Guadalajara and semi-urban and rural areas in the center of the peninsula. It is important to highlight the complexity of flying over the center of Madrid, which is subject to many restrictions on air traffic.
The data obtained demonstrate the presence of various types of microplastics and synthetic fibers, which are particularly abundant in Madrid compared to rural and less populated areas.
Identified plastics include polyesters, polyamides, and polyolefins, which are among the most widely used plastics, as well as man-made fibers such as viscose or dyed cotton, especially blue.
The measured concentration reached 13.9 microplastics per cubic meter in Madrid, about ten times more than in rural areas. With this we have been able to estimate the total number of microplastics in the air over the center of Madrid at approximately one trillion particles.
The fate of microplastics
Our study, recently published in the journal Science of the Total Environment, includes a calculation of trajectories and deposition rates using estimates of air mass movement.
We have determined that many of the microplastic particles settle in the first 24 hours not too far from the point where they were sampled. However, a significant number are capable of traveling long distances before being deposited.
Specifically, the deposit rates for the Bay of Biscay area would be between 0.1 and 10 microplastics per square meter per day, considering only the particles that left Madrid 24 hours before. Furthermore, a significant fraction of microplastics can reach southern England, Belgium and northern France, more than a thousand kilometers from where they were detected.
Pollution of urban origin and global nature
Our study is the first direct evidence of the presence of microplastics in the atmosphere at high altitude. Microplastics concentrations were about ten times higher in urban areas than in rural areas, which supports the eminently urban origin of this type of contamination.
We detect not only plastics or synthetic polymers, but also natural fibers from industrial fabrics. The trajectory simulation data indicate that the smallest particles can be deposited hundreds or thousands of kilometers from Madrid, demonstrating the global nature of the contamination of the atmosphere by microplastics.
Roberto Rosal, Professor of Chemical Engineering, University of Alcalá; Ángeles Aguilera, Coordinator of the Microbial Diversity and Evolution Group, Astrobiology Center (INTA-CSIC); Carlos Edo, Doctoral Student in Hydrology and Water Resources Management. Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá; Francisca Fernández Piñas, Professor of Biology, Autonomous University of Madrid and Miguel González-Pleiter, Researcher in Ecotoxicology, Autonomous University of Madrid
This article was originally published on The Conversation. Read the original.
