Description

News release on recent research paper with associated journal cover:

Grimy windows could be harbouring toxic pollutants

Dirty windows can harbour potentially harmful pollutants under films of fatty acids from cooking emissions – and these can hang around over long periods.

Illustration showing pollution build-up on a window

 

According to a new study, led by researchers at the University of Birmingham, the fatty acids contained within cooking emissions are highly stable and not easily broken down in the atmosphere.

That means that when they hit a solid surface, like a window, they form a self-organised thin film which builds up over time and will only be very slowly broken down by other chemicals in the atmosphere. During this process, the film will become rougher and attract more water from the humidity in the air. In addition, toxic pollutants can become trapped underneath this persistent crust and are then protected from breakdown in the atmosphere.

Senior author Dr Christian Pfrang said: “The fatty acids in these films are not, by themselves, particularly harmful – but because they are not being broken down, they are effectively protecting any other pollutants that might be trapped underneath.”

The study, featuring on the front cover of Environmental Science: Atmospheres (published on 15 September 2022), was carried out in partnership with experts from the University of Bath, Diamond Light Source and ISIS Neutron and Muon Source in the UK, and the Institut Laue-Langevin in France.

The team worked on laboratory ‘proxies’ – samples of material engineered in the lab to approximate ‘real world’ samples. These were spun into super-thin films of pollution, just a few tens of nanometres in thickness.

The researchers used both neutrons and X-rays to study the nano-scale composition of the films and the changes in their surface structures. By changing the humidity and amount of ozone – a key pollutant indoors and outdoors – the researchers were also able to mimic the behaviour of the films over time.

They found that the self-organised arrangement within the films in repeating molecular sheets – a so-called lamellar phase – made it difficult for smaller molecules, like ozone, to access the reactive parts of the fatty acids within these structures. Once deposited and exposed to ozone, the surfaces of the films became less smooth and increasingly likely to take up water, an effect which also has implications for the formation and lifetime of aerosols in the atmosphere.

Period15 Sept 2022 → 3 Nov 2022

Media coverage

4

Media coverage

  • TitleScientists Reveal Why You Should Clean Your Dirty Windows
    Degree of recognitionInternational
    Media name/outletSciTechDaily
    Media typeWeb
    Country/TerritoryUnited States
    Date3/11/22
    DescriptionThe study found that grimy windows can harbor potentially toxic pollutants.

    The windows could be harboring toxic pollutants.

    Dirty windows may harbor potentially harmful pollutants behind protective films of fatty acids from cooking emissions, which can linger for extended periods of time.

    A recent study conducted by scientists at the University of Birmingham found that the fatty acids present in cooking emissions are extremely stable and difficult to break down in the atmosphere.


    This means that when they collide with a solid surface, like a window, they create a thin, self-organized film that slowly accumulates and can only be gradually broken down by other chemicals in the atmosphere. The film will become rougher throughout this process and draw more water from the humidity in the air. Furthermore, harmful pollutants have the potential to become trapped within this resilient crust, where they are then shielded from breakdown in the atmosphere.

    Senior author Dr. Christian Pfrang said: “The fatty acids in these films are not, by themselves, particularly harmful – but because they are not being broken down, they are effectively protecting any other pollutants that might be trapped underneath.”

    The study, which was featured on the front cover of the journal Environmental Science: Atmospheres, was carried out in partnership with experts from the University of Bath, Diamond Light Source and ISIS Neutron and Muon Source in the UK, and the Institut Laue-Langevin in France.


    The team worked on laboratory ‘proxies’ – samples of material engineered in the lab to approximate ‘real world’ samples. These were spun into super-thin films of pollution, just a few tens of nanometres in thickness.

    The researchers used both neutrons and X-rays to study the nano-scale composition of the films and the changes in their surface structures. By changing the humidity and amount of ozone – a key pollutant indoors and outdoors – the researchers were also able to mimic the behavior of the films over time.

    They found that the self-organized arrangement within the films in repeating molecular sheets – a so-called lamellar phase – made it difficult for smaller molecules, like ozone, to access the reactive parts of the fatty acids within these structures. Once deposited and exposed to ozone, the surfaces of the films became less smooth and increasingly likely to take up water, an effect which also has implications for the formation and lifetime of aerosols in the atmosphere.

    Reference: “The evolution of surface structure during simulated atmospheric ageing of nano-scale coatings of an organic surfactant aerosol proxy” by Adam Milsom, Adam M. Squires, Maximilian W. A. Skoda, Philipp Gutfreund, Eleonore Mason, Nicholas J. Terrill and Christian Pfrang, 25 May 2022, Environmental Science: Atmospheres.
    DOI: 10.1039/D2EA00011C
    PersonsChristian Pfrang, Adam Milsom
  • TitleDirty Kitchen Windows Could be Hiding Toxic Pollutants
    Degree of recognitionInternational
    Media name/outletLaboratory Equipment
    Media typeWeb
    Country/TerritoryUnited States
    Date16/09/22
    DescriptionKey Points:

    Dirty windows can harbor potentially harmful pollutants under protective films of fatty acids from cooking emissions, according to a new study.
    Fatty acids contained within cooking emissions are highly stable and not easily broken down in the atmosphere.
    Ozone, a key pollutant both indoors and out, altered the surface of the protective films.

    The dinner you cook tonight may stay on your kitchen windows for years, according to a new study by researchers at the University of Birmingham. According to the team, the fatty acids contained within cooking emissions not only cling to hard surfaces for long periods of time, but also inadvertently form protective films to cover potentially harmful pollutants.

    Once fatty acids hit a solid surface, such as a window, they form a self-organized thin film that builds up over time, only very slowly being broken down by other chemicals in the atmosphere. During this process, the film becomes rougher and attracts more water from the humidity in the air. Toxic pollutants can then become trapped underneath this persistent crust and are then protected from breakdown in the atmosphere.

    “The fatty acids in these films are not, by themselves, particularly harmful but because they are not being broken down, they are effectively protecting any other pollutants that might be trapped underneath,” said senior study author Christian Pfrang.

    For the study, published in Environmental Science Atmospheres, the researchers engineered material proxies that were then spun into super-thin films of pollution. Pfrang and his team used both neutrons and X-rays to study the nano-scale composition of the films and the changes in their surface structures. By changing the humidity and amount of ozone—a key pollutant—the researchers were also able to mimic the behavior of the films over time.

    They found that the self-organized arrangement within the films in repeating molecular sheets made it difficult for smaller molecules, like ozone, to access the reactive parts of the fatty acids within these structures. Once deposited and exposed to ozone, the surfaces of the films became less smooth and increasingly likely to take up water, an effect that also has implications for the formation and lifetime of aerosols in the atmosphere.
    PersonsChristian Pfrang
  • TitleSchmutzige Fenster könnten giftige Schadstoffe beherbergen
    Degree of recognitionInternational
    Media name/outletEarthPressNews.com
    Media typeWeb
    Country/TerritoryGermany
    Date16/09/22
    DescriptionSchmutzige Fenster können unter Schutzfilmen aus Fettsäuren aus Kochabgasen potenziell schädliche Schadstoffe beherbergen – und diese können über lange Zeiträume herumliegen.

    Laut einer neuen Studie, die von Forschern der University of Birmingham geleitet wurde, sind die in Kochabgasen enthaltenen Fettsäuren sehr stabil und werden in der Atmosphäre nicht leicht abgebaut.

    Das heißt, wenn sie auf eine feste Oberfläche wie ein Fenster treffen, bilden sie einen selbstorganisierten dünnen Film, der sich mit der Zeit aufbaut und nur sehr langsam von anderen Chemikalien in der Atmosphäre abgebaut wird. Während dieses Vorgangs wird der Film rauer und zieht mehr Wasser aus der Luftfeuchtigkeit an. Darüber hinaus können giftige Schadstoffe unter dieser hartnäckigen Kruste eingeschlossen werden und dann vor dem Abbau in der Atmosphäre geschützt werden.

    Seniorautor Dr. Christian Pfrang sagt, dass „die Fettsäuren in diesen Filmen an sich nicht besonders schädlich sind – aber weil sie nicht abgebaut werden, schützen sie effektiv alle anderen Schadstoffe, die darunter eingeschlossen sein könnten.“

    Die Studie, abgebildet auf der Titelseite von Umweltwissenschaften: Atmosphären wurde in Partnerschaft mit Experten der University of Bath, der Diamond Light Source und der ISIS Neutron and Myon Source im Vereinigten Königreich sowie dem Institut Laue-Langevin in Frankreich durchgeführt.

    Das Team arbeitete an Labor-„Proxys“ – Materialproben, die im Labor entwickelt wurden, um Proben aus der „realen Welt“ anzunähern. Diese wurden zu superdünnen Verschmutzungsfilmen gesponnen, die nur wenige zehn Nanometer dick waren.

    Die Forscher verwendeten sowohl Neutronen als auch Röntgenstrahlen, um die nanoskalige Zusammensetzung der Filme und die Veränderungen ihrer Oberflächenstrukturen zu untersuchen. Durch die Änderung der Luftfeuchtigkeit und der Ozonmenge – einem wichtigen Schadstoff im Innen- und Außenbereich – konnten die Forscher auch das Verhalten der Filme im Laufe der Zeit nachahmen.

    Sie fanden heraus, dass die selbstorganisierte Anordnung innerhalb der Filme in sich wiederholenden molekularen Schichten – eine sogenannte lamellare Phase – es kleineren Molekülen wie Ozon erschwerte, an die reaktiven Teile der Fettsäuren innerhalb dieser Strukturen heranzukommen. Einmal abgelagert und Ozon ausgesetzt, wurden die Oberflächen der Filme weniger glatt und nahmen zunehmend Wasser auf, ein Effekt, der auch Auswirkungen auf die Bildung und Lebensdauer von Aerosolen in der Atmosphäre hat.

    Mehr Informationen:
    Adam Milsom et al., Die Entwicklung der Oberflächenstruktur während der simulierten atmosphärischen Alterung von nanoskaligen Beschichtungen eines organischen Tensid-Aerosol-Proxys, Umweltwissenschaften: Atmosphären (2022). DOI: 10.1039/D2EA00011C
    PersonsChristian Pfrang
  • TitleGrimy windows could be harbouring toxic pollutants
    Degree of recognitionInternational
    Media name/outletPhys.Org
    Media typeWeb
    Country/TerritoryUnited Kingdom
    Date15/09/22
    DescriptionDirty windows can harbor potentially harmful pollutants under protective films of fatty acids from cooking emissions—and these can hang around over long periods of time.

    According to a new study, led by researchers at the University of Birmingham, the fatty acids contained within cooking emissions are highly stable and not easily broken down in the atmosphere.

    That means that when they hit a solid surface, like a window, they form a self-organized thin film which builds up over time and will only be very slowly broken down by other chemicals in the atmosphere. During this process, the film will become rougher and attract more water from the humidity in the air. In addition, toxic pollutants can become trapped underneath this persistent crust and are then protected from breakdown in the atmosphere.

    Senior author Dr. Christian Pfrang says that "the fatty acids in these films are not, by themselves, particularly harmful—but because they are not being broken down, they are effectively protecting any other pollutants that might be trapped underneath."

    The study, featuring on the front cover of Environmental Science: Atmospheres, was carried out in partnership with experts from the University of Bath, Diamond Light Source and ISIS Neutron and Muon Source in the UK, and the Institut Laue-Langevin in France.

    The team worked on laboratory 'proxies'—samples of material engineered in the lab to approximate 'real world' samples. These were spun into super-thin films of pollution, just a few tens of nanometers in thickness.

    The researchers used both neutrons and X-rays to study the nano-scale composition of the films and the changes in their surface structures. By changing the humidity and amount of ozone—a key pollutant indoors and outdoors—the researchers were also able to mimic the behavior of the films over time.

    They found that the self-organized arrangement within the films in repeating molecular sheets—a so-called lamellar phase—made it difficult for smaller molecules, like ozone, to access the reactive parts of the fatty acids within these structures. Once deposited and exposed to ozone, the surfaces of the films became less smooth and increasingly likely to take up water, an effect which also has implications for the formation and lifetime of aerosols in the atmosphere.
    PersonsChristian Pfrang

Media contributions

2

Media contributions

  • TitleGrimy windows could be harbouring toxic pollutants
    Degree of recognitionInternational
    Media name/outletUniversity of Birmingham
    Media typeWeb
    Country/TerritoryUnited Kingdom
    Date21/09/22
    DescriptionDirty windows can harbour potentially harmful pollutants under films of fatty acids from cooking emissions – and these can hang around over long periods.

    According to a new study, led by researchers at the University of Birmingham, the fatty acids contained within cooking emissions are highly stable and not easily broken down in the atmosphere.

    That means that when they hit a solid surface, like a window, they form a self-organised thin film which builds up over time and will only be very slowly broken down by other chemicals in the atmosphere. During this process, the film will become rougher and attract more water from the humidity in the air. In addition, toxic pollutants can become trapped underneath this persistent crust and are then protected from breakdown in the atmosphere.

    Senior author Dr Christian Pfrang said: “The fatty acids in these films are not, by themselves, particularly harmful – but because they are not being broken down, they are effectively protecting any other pollutants that might be trapped underneath.”

    The fatty acids in these films are not, by themselves, particularly harmful – but because they are not being broken down, they are effectively protecting any other pollutants that might be trapped underneath.
    Dr Christian Pfrang, School of Geography, Earth and Environmental Sciences
    The study, featuring on the front cover of Environmental Science: Atmospheres (published on 15 September 2022), was carried out in partnership with experts from the University of Bath, Diamond Light Source and ISIS Neutron and Muon Source in the UK, and the Institut Laue-Langevin in France.

    The team worked on laboratory ‘proxies’ – samples of material engineered in the lab to approximate ‘real world’ samples. These were spun into super-thin films of pollution, just a few tens of nanometres in thickness.

    The researchers used both neutrons and X-rays to study the nano-scale composition of the films and the changes in their surface structures. By changing the humidity and amount of ozone – a key pollutant indoors and outdoors – the researchers were also able to mimic the behaviour of the films over time.

    They found that the self-organised arrangement within the films in repeating molecular sheets – a so-called lamellar phase – made it difficult for smaller molecules, like ozone, to access the reactive parts of the fatty acids within these structures. Once deposited and exposed to ozone, the surfaces of the films became less smooth and increasingly likely to take up water, an effect which also has implications for the formation and lifetime of aerosols in the atmosphere.
    Producer/AuthorBeck Lockwood
    PersonsChristian Pfrang
  • TitleGrimy windows could be harbouring toxic pollutants
    Degree of recognitionInternational
    Media name/outletSTFC,RAL,ISIS
    Media typeWeb
    Country/TerritoryUnited Kingdom
    Date16/09/22
    DescriptionDirty windows can harbour potentially harmful pollutants under protective films of fatty acids from cooking emissions – and these can hang around for long periods of time.


    According to a new study, the fatty acids emitted during cooking are highly stable and not easily broken down in the atmosphere. That means that, when they hit a solid surface such as a window, they form a self-organised thin film that builds up over time and will only be very slowly broken down by other chemicals in the atmosphere.

    During this process, the film will become rougher and attract more water from the humidity in the air. In addition, toxic pollutants can become trapped underneath this persistent crust and are then protected from breakdown in the atmosphere. Dr Christian Pfrang from the University of Birmingham said: “The fatty acids in these films are not, by themselves, particularly harmful – but because they are not being broken down, they are effectively protecting any other pollutants that might be trapped underneath."

    In the study, which features on the inside front cover of Environmental Science: Atmospheres, the team studied laboratory 'proxies', engineered in the lab to act as a model of 'real world' samples. These were spun into super-thin films of pollution, just a few tens of nanometres in thickness.

    The researchers used the INTER beamline at ISIS, as well as experiments at Diamond Light Source and the ILL to study the nano-scale composition of the films and the changes in their surface structures. By changing the humidity and amount of ozone, which is a key pollutant indoors and outdoors, the researchers were also able to mimic the behaviour of the films over time.

    They found that the self-organised arrangement within the films in repeating molecular sheets, known as a lamellar phase, made it difficult for smaller molecules such as ozone to access the reactive parts of the fatty acids within these structures. Once deposited and exposed to ozone, the surfaces of the films became less smooth and increasingly likely to take up water, an effect which also has implications for the formation and lifetime of aerosols in the atmosphere.

    The full paper can be found at: The evolution of surface struct​ure during simulated atmospheric ageing of nano-scale coatings of an organic surfactant aerosol proxy.
    Producer/AuthorRosie de Laune
    PersonsChristian Pfrang