Passive air samplers map shared outdoor bacteria and more varied fungi across five East African cities

Researchers used foam air samplers to identify the bacteria and fungi people may be breathing in 10 sites across five countries.

Abstract editorial illustration accompanying the article: Passive air samplers map shared outdoor bacteria and more varied fungi across five East African cities

Editorial illustration — not from the study.

The researchers collected airborne microbes from 10 locations in five East African countries—Burundi, the Democratic Republic of the Congo, Kenya, Rwanda, and Tanzania—using polyurethane foam passive air samplers deployed at the same time. They then used DNA sequencing to identify bacterial and fungal groups in the air.

At the genus level, several bacteria and fungi commonly found outdoors were detected across sites. Country-level comparisons showed no significant differences for bacteria, while fungi differed significantly among countries; the patterns also did not consistently track distance between nearby locations.

What they found in air

Using DNA sequencing of samples collected with polyurethane foam passive air samplers, the study detected multiple bacterial genera commonly found in outdoor air (including Massilia, Sphingomonas, Pseudomonas, Bacillus, and Kocuria) and multiple fungal genera (including Cladosporium, Alternaria, Aspergillus, Curvularia, and Penicillium).

When the team compared sites by country, bacterial communities did not show significant differences (ANOSIM R = −0.045, p = 0.597). Fungal communities did show significant differences among countries (ANOSIM R = 0.652, p = 0.002). In cross-border comparisons, nearby sites within 10 km did not consistently have similar microbial profiles.

What it suggests about exposure

The results suggest there is a broadly shared regional “aerobiome” for bacteria across the surveyed East African cities, while fungal communities show stronger location-by-country patterning. The study also demonstrates that passive foam samplers can be used to characterize airborne microbial communities in the region.

Evidence and study caveats

This is a regional survey using passive air sampling deployed concurrently across 10 sites in five countries, followed by 16S rRNA gene and ITS amplicon sequencing and community comparisons. The authors describe their work as a proof-of-concept and note that stronger public health surveillance would require enhanced temporal replication and broader spatial coverage; the abstract does not provide details on sampling duration, seasonality, or how many repeat time points were used.

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