Indoor Airborne Microbiome and Endotoxin: Meteorological Events and Occupant Characteristics Are Important Determinants

Hesham Amin, Tina Šantl-Temkiv, Christine Cramer, Kai Finster, Francisco Gomez Real, Thorarinn Gislason, Mathias Holm, Christer Janson, Nils Oskar Jögi, Rain Jogi, Andrei Malinovschi, Ian P G Marshall, Lars Modig, Dan Norbäck, Rajesh Shigdel, Torben Sigsgaard, Cecilie Svanes, Hulda Thorarinsdottir, Inge M Wouters, Vivi SchlünssenRandi J Bertelsen

Research output: Contribution to journalArticleAcademicpeer-review


Airborne bacteria and endotoxin may affect asthma and allergies. However, there is limited understanding of the environmental determinants that influence them. This study investigated the airborne microbiomes in the homes of 1038 participants from five cities in Northern Europe: Aarhus, Bergen, Reykjavik, Tartu, and Uppsala. Airborne dust particles were sampled with electrostatic dust fall collectors (EDCs) from the participants' bedrooms. The dust washed from the EDCs' clothes was used to extract DNA and endotoxin. The DNA extracts were used for quantitative polymerase chain (qPCR) measurement and 16S rRNA gene sequencing, while endotoxin was measured using the kinetic chromogenic limulus amoebocyte lysate (LAL) assay. The results showed that households in Tartu and Aarhus had a higher bacterial load and diversity than those in Bergen and Reykjavik, possibly due to elevated concentrations of outdoor bacterial taxa associated with low precipitation and high wind speeds. Bergen-Tartu had the highest difference (ANOSIM R = 0.203) in β diversity. Multivariate regression models showed that α diversity indices and bacterial and endotoxin loads were positively associated with the occupants' age, number of occupants, cleaning frequency, presence of dogs, and age of the house. Further studies are needed to understand how meteorological factors influence the indoor bacterial community in light of climate change.

Original languageEnglish
Pages (from-to)11750–11766
Number of pages17
JournalEnvironmental Science & Technology
Issue number32
Early online date31 Jul 2023
Publication statusPublished - 15 Aug 2023


  • Northern Europe
  • airborne microbiome
  • meteorological data
  • 16S rRNA and occupants’ age


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