A new study shows that the concentration of potentially harmful chemical compounds in dust collected by air filtration systems on the International Space Station (ISS) exceeds the concentration in dust on the floors of many American homes. In a first-of-its-kind study, scientists analyzed a sample of dust from air filters on the ISS and found higher-than-average levels of organic pollutants found in homes in the US and Western Europe.

Posting your results Environmental Science and Technology Letters Researchers from the University of Birmingham in the UK and NASA’s Glenn Research Center in the US say their findings could guide the design and construction of future spacecraft.

Contaminants found in “space dust” include polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), “new” brominated flame retardants (BFRs), organophosphorus ethers (OPEs), polycyclic aromatic hydrocarbons (PAHs), perfluoroalkyl substances (PFASs) and polychlorinated biphenyls (PCBs). BFR and OPE are used in many countries to meet fire safety regulations in consumer and commercial applications such as electrical and electronic equipment, building insulation, furniture fabrics and foams.

PAHs are found in hydrocarbon fuels and are released during combustion, PCBs are used in building and window sealants and as dielectric fluids in electrical equipment, while PFASs have been used to prevent stains on fabrics and clothing. However, their potential effects on human health have led to some of them being banned or restricted in their use.

PCBs, some PFASs, HBCDDs and commercial formulations of PBDE penta-octa- and deca-BDE are classified as persistent organic pollutants (POPs) under the UNEP Stockholm Convention. In addition, some PAHs are classified as human carcinogens, while some OPEs are considered a restriction by the European Chemicals Agency.

Co-author Professor Stuart Harrad, from the University of Birmingham, said: “Our findings have implications for future space stations and habitats where many sources of pollution can be eliminated through careful material selection in the early stages of design and construction.

“Although the concentrations of organic pollutants found in dust from the ISS often exceed the average values ​​found in homes and other environments in the US and Western Europe, the levels of these compounds were generally within the range observed on Earth.”

The researchers note that the concentration of PBDE in the dust sample, which falls within the concentration range found in US household dust, may indicate that inorganic FRs such as ammonium dihydrogen phosphate were used on the ISS to make fabrics and tapes flame retardant. They believe that the use of commercially available off-the-shelf products such as cameras, MP3 players, tablet computers, medical devices and clothing brought aboard for personal use by astronauts is a potential source of many of the chemicals detected.

The air inside the ISS is constantly recirculated at 8-10 changes per hour. Even if CO removal takes place₂ and trace polluting gases, the extent to which this removes chemicals such as BFRs is unknown. Highly ionizing radiation can accelerate the aging of materials, including the breakdown of plastic products into airborne micro and nanoplastics in a microgravity environment. This may cause the concentrations and relative abundances of PBDEs, HBCDDs, NBFRs, OPEs, PAHs, PFASs and PCBs in ISS dust to differ markedly from those in dust from terrestrial indoor microenvironments.

The scientists measured the concentrations of a number of target chemicals in the dust collected from the ISS. In a microgravity environment, particles float around according to the flow pattern of the ventilation system and eventually settle on surfaces and air intakes.

The meshes that cover ISS HEPA filters collect these debris, which requires weekly vacuuming to maintain effective filtration. The material in ISS vacuum bags consists of airborne particles, lint on clothing, hair, and other debris often described as spacecraft cabin dust. Several vacuum bags were sent back to Earth to study this unique powder, and a small sample was sent to the University of Birmingham for analysis as part of the study. Source