Respro® Bulletin Board

In a new study, an international team of researchers investigates the atmosphere as a relevant source of plastic pollution in our planet’s waters

According to estimates, by 2040 the level of plastic pollution could reach 80 million metric tons per year. Plastic particles have now been detected in virtually all spheres of the environment, e.g. in water bodies, the soil and the air. Via ocean currents and rivers, the tiny plastic particles can even reach the Arctic, Antarctic or ocean depths. A new overview study has now shown that wind, too, can transport these particles great distances – and much faster than water can: in the atmosphere, they can travel from their point of origin to the most remote corners of the planet in a matter of days. In the journal Nature Reviews Earth and Environment, an international team of researchers – including experts from the Alfred Wegener Institute, the Institute for Advanced Sustainability Studies in Potsdam, and the GEOMAR Helmholtz Centre for Ocean Research in Kiel – describes how microplastic finds its way into the atmosphere and how it is subsequently transported.

Today, between 0.013 and 25 million metric tons of micro- and nanoplastic per year are transported up to thousands of kilometres by ocean air, snow, sea spray and fog, crossing countries, continents and oceans in the process. This estimate was arrived at by an international team of 33 researchers, including experts from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), the Institute for Advanced Sustainability Studies in Potsdam (IASS) and the GEOMAR Helmholtz Centre for Ocean Research in Kiel.

“Air is a much more dynamic medium than water,” says co-author Dr Melanie Bergmann from the AWI. “As a result, micro- and nanoplastic can much more quickly penetrate those regions of our planet that are most remote and still largely untouched.” Once there, the particles could affect the surface climate and the health of local ecosystems. For example, when these darker particles are deposited on snow and ice, they affect the ice-albedo feedback, reducing their ability to reflect sunlight and promoting melting. Similarly, darker patches of seawater absorb more solar energy, further warming the ocean. And in the atmosphere, microplastic particles can serve as condensation nuclei for water vapour, producing effects on cloud formation and, in the long term, the climate.

How do plastic particles get into the atmosphere?

First of all, through human activities. Particles produced by tyres and brakes in road traffic, or by the exhaust gases from industrial processes, rise into the atmosphere, where they are transported by winds. However, according to the overview study, there is also evidence suggesting that a substantial number of these particles are transported by the marine environment. Initial analyses indicate that microplastic from the coastal zone also finds its way into the ocean through eroded beach sand. The combination of sea spray, wind and waves forms air bubbles in the water containing microplastic. When the bubbles burst, the particles find their way into the atmosphere. As such, transport to remote and even polar regions could be due to the combination of atmospheric and marine transport.

Consequently, it is important to understand interactions between the atmosphere and ocean, so as to determine which particle sizes are transported, and in which quantities. The atmosphere predominantly transports small microplastic particles, which makes it a much faster transport route that can lead to substantial deposits in a broad range of ecosystems. As Melanie Bergmann explains: “We need to integrate micro- and nanoplastic in our measurements of air pollution, ideally on an international scale as part of global networks.” For this purpose, in a first step, first author Deonie Allen and Bergmann began collecting samples of microplastic in the air, seawater and ice during a Polarstern expedition to the Arctic last year.

Joining forces to grasp the microplastic cycle

Understanding and characterising the microplastic cycles between the ocean and atmosphere will require joint efforts. In this regard, in the study, the team of researchers led by first authors Deonie Allen and Steve Allen from the University of Strathclyde, Glasgow, outlines a global strategy for creating a seamless, intercomparable database on the flow of micro- and nanoplastic between the ocean and atmosphere. “There are so many aspects of the emissions, transport and effects of microplastic in the atmosphere that we still don’t fully understand,” says co-author Prof Tim Butler from the IASS. “This publication reveals the gaps in our knowledge – and presents a roadmap for the future.”

Two dedicated working groups from the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) prepared the study. According to study co-author and GESAMP member Prof Sylvia Sander from GEOMAR: “The study makes it clear that a comprehensive grasp of the ocean, and of the effects of human influences on it, can only be achieved by networking researchers and their data. The great challenges of our time are at the global scale. Accordingly, we have to pursue answers to pressing questions with expertise that is as comprehensive and international as possible. That can only be done by working together.” GESAMP is a conglomerate of eleven organisations belonging to the United Nations. Its goal is to arrive at a multidisciplinary, science-based understanding of the marine environment. To date, the network has already collaborated with more than 500 experts from countries around the globe on a range of questions.

Micro- and nanoplastic in the air is also relevant for human health. In a recently released British study, microplastic was detected in the lungs of 11 of 13 living human beings. “This is yet another reason why we need to integrate plastic into monitoring programmes for air quality,” Bergmann stresses. In order to reduce environmental pollution from plastic, the production of new plastic would also need to be successively reduced on the basis of an international treaty, as Bergmann and other experts recently called for in a letter to the journal Science.

Original publication

Deonie Allen et al.: Micro- and nanoplastics in the marine-atmospheric environment. Nature Reviews Earth & Environment (2022). DOI: https://doi.org/10.1038/s43017-022-00292-x

Micro- and nanoplastic from the atmosphere is | EurekAlert!

An anti-idling campaign at two elementary schools was effective in reducing idling time by 38%, and an air monitoring experiment found that air quality around schools can vary over short distances. These findings, published in the journal Atmosphere, can help schools and school districts plan to protect students, staff and the community from unhealthy air pollution both indoors and outdoors.

“Idling at schools during drop-off and pick-up times is a substantial problem,” says study lead author Daniel Mendoza, a research assistant professor in the University of Utah’s Department of Atmospheric Sciences and visiting assistant professor in the Department of City & Metropolitan Planning. “The anti-idling campaign was effective in reducing not only the number of vehicles idling but also the length of idling.”

Mendoza and colleagues, including Tabitha Benney, an associate professor of political science, are studying the sources and impacts of air pollution along the Wasatch Front, a region with bowl-like geography that leads to air quality issues. U scientists have developed mobile tools to monitor air quality, including a van filled with research-grade air sensors that’s been affectionately named the “Nerdmobile.” For this study, the Nerdmobile was parked outside Willow Springs Elementary and Bonneville Elementary for a week at a time in each school’s pick-up/drop-off zone. The measurements at the van were then compared with air quality measurements inside the school and near the school’s playground.

They’re also interested in the social impacts of air quality. For this study, they partnered with researchers at Westminster College who used the U.S. Environmental Protection Agency’s Idle-Free Schools Toolkit to conduct an intensive three-month anti-idling campaign involving teachers and parents. “It was extremely important to us that the campaign involved the school community every step of the way,” says Rachel Forrest, adjunct professor in the Public Health Program, School of Nursing and Health Sciences, Westminster College. “Community members helped shape the look and feel of the campaign and donated their time and expertise to implement it. Without their support, this wouldn’t have been possible.”

And it worked. The researchers found 38% less idling time and 11% fewer cars idling after the campaign than before.

The researchers intended to follow up several months later to see how well the effects of the campaign persisted, but unfortunately, school closures due to the COVID-19 pandemic abruptly ended the study in March 2020.”

Reduced idling has numerous advantages,” Mendoza says. “The most important one is the substantial reduction of concentrated pollution in a relatively small area.” Recent research from Mendoza, Benney and colleagues found that indoor air quality in two Salt Lake City high schools was impacted by outdoor air quality.

Idling can also unnecessarily burn fuel — a fact that becomes more relevant as gas prices have risen in recent months.

Why do parents idle when dropping off or picking up? It’s usually to maintain a comfortable temperature in the car, but studies have found that it takes 10-15 minutes for in-car temperatures to change enough to be uncomfortable.

What did the team learn about air pollution from idling? Another unfortunate setback, a winter inversion, which traps emissions in the cold valley under a lid of warm air and impairs air quality, set in during the study period, confounding the measurements and making the effect of reduced idling on air quality unclear.

“However, what the inversion helped us see more clearly was the lasting effects of idling around schools as there were marked pollution spikes following drop-off and pick-up times,” Mendoza says. The researchers also noticed that the amount of particulate matter air pollution dropped off between the van parked in the pickup lane and the school playgrounds, highlighting the localized air pollution caused by car emissions.

“It is not only parents but also school buses that have been culprits of localized pollution hotspots around schools,” Mendoza says. Many school districts, he says, have already enacted idling bans for buses. “However, parents are a completely different story.”

Anti-idling campaign reduces idling time at elementary schools: ‘Nerdmobile’ sampled air quality in pick-up/drop-off line during the study — ScienceDaily