Family dust could not settle onboard the Worldwide House Station, but it surely nonetheless accommodates poisonous compounds. Credit score: NASA
In science fiction, space stations typically look shiny and pristine, the final word managed atmosphere cocooning people from the harshness of space. However in actuality, the Worldwide House Station fills with dust. Not cosmic dust, however family dust: pores and skin flakes, clothes lint — and poisonous chemical compounds.
An evaluation of samples taken from the Worldwide House Station (ISS) has discovered that the dust onboard accommodates higher-than-average ranges of a number of probably dangerous sorts of chemical compounds in comparison with dust in houses on Earth.
For some compounds, these ranges are increased than ever reported in family dust. These embody perfluorooctanoic acid (PFOA), a compound typically present in non-stick and stain-resistant merchandise, meals packaging, and fire-fighting foam. On the space station, the extent of PFOA was round 3.3 components per million; as compared, the best stage present in a 2008 survey of U.S. houses and daycare facilities was about 2.0 components per million.
The combo of chemical compounds discovered within the dust replicate the necessities of the space station’s “distinctive indoor atmosphere,” the authors write of their examine, printed Aug. 8 in Environmental Science and Expertise. As a result of probably disastrous penalties of an onboard hearth, “very cautious consideration is paid to flammability of ISS contents.” Among the chemical compounds discovered are used as flame-retarding supplies or therapies in onboard foams, webbing, and materials. And the excessive ranges of PFOA could also be because of the widespread use of waterproofing therapies which stop microbes from rising onboard.
What’s within the dust?
Mud doesn’t settle in microgravity — just like the astronauts themselves, it floats around. However this doesn’t imply the astronauts can skip dusting chores. The astronauts must repeatedly vacuum screens that cowl the intakes of their air filters to clear them of huge dust particles.
To check what the astronauts are respiratory, Harrad and his colleagues analyzed the contents of ISS vacuum baggage that had been returned to Earth. The luggage are crammed with cabin dust: steel particles, lint from garments, hair, pores and skin flakes, and different particles. The analysis is a part of an experiment known as Divert Undesirable House Trash (DUST) that appears at particles and their habits in a microgravity atmosphere.
Upon analyzing the dust, researchers discovered a number of varieties of natural contaminants. (In chemistry, natural merely signifies that a compound accommodates carbon.)
These embody organophosphate esters (OPEs) and brominated flame retardants (BFRs) — chemical compounds which might be used to satisfy hearth security rules for issues like constructing insulation, furnishings materials, carpets, and foams. OPEs and BFRs leech out of merchandise over time, and research have discovered that they’ll adversely affect children’s health.
The authors write that BFR ranges onboard the ISS could rise as a result of astronauts generally vacuum the wall panels and acoustic insulation. And foam is ubiquitous onboard the space station as a result of it’s used to pack and shield objects from the violent shaking when they’re delivered by way of rocket launch.
One shock within the ISS dust was within the class of compounds known as polychlorinated biphenyls (PCBs). PCBs might be present in outdated homes in home windows, constructing sealants, and electrical gear — however they had been banned in america in 1979. What’s extra, the actual varieties of PCBs discovered on the ISS are uncommon and sudden for indoor dust on Earth, the researchers say. They think it might need come from dyes and paint pigments used onboard.
The examine additionally recognized polycyclic fragrant hydrocarbons (PAHs), that are present in hydrocarbon fuels and are emitted from combustion processes; perfluoroalkyl substances (PFAS) utilized in staining purposes for clothes and different materials; and polybrominated diphenyl ethers (PBDEs), which can be from using inorganic flame retardants in webbing and materials.
The group additionally suspects that some chemical compounds present in ISS dust could come from plastic housings in objects that astronauts deliver with them for private use, like MP3 gamers, cameras, and tablets — all of which might comprise flame-retardant coatings.
Clearing the air
The group notes that though the air onboard the ISS is consistently filtered and recirculated a number of occasions per hour, researchers don’t know what number of BFRs are eliminated on this course of.
As for why there are excessive ranges of chemical compounds on the ISS within the first place, it might partly must do with the upper ranges of ionizing radiation in orbit. The radiation ages supplies on the space station sooner, breaking the plastic into micro and nano plastics that float within the microgravity atmosphere.
The researchers say their work will help engineers in selecting much less poisonous supplies in future spacecraft. “It could be potential to exclude many contaminant sources by cautious materials decisions within the early phases of design and development,” mentioned Stuart Harrad, a examine writer and environmental chemist on the College of Birmingham, U.Ok., in a statement.
