Every time you take a breath, you draw in countless microbes. But which ones? Researchers previously believed that the airborne microorganisms were largely uniform regardless of location.
However, recent findings challenge that assumption. A 14-month citizen science initiative conducted across the country collected and analyzed airborne dust, resulting in the creation of the first comprehensive atlas of airborne bacteria and fungi in the continental United States. The diversity of microscopic life found in the air is impressive.
Over 1,400 volunteers participated by swabbing surfaces in 1,200 households, particularly in areas that are often overlooked during cleaning. These dust samples captured a significant variety of microbes, identifying around 112,000 bacterial and 57,000 fungal phylotypes (which are essentially family groups).
Most of these microorganisms are benign, with only a few pathogens and allergens showing a geographic concentration. For instance, the fungal genus Alternaria, a known allergen, is common but most prevalent in the Midwest. The fungus Cladosporium appears in localized hotspots throughout the eastern regions, particularly in the South and Mid-Atlantic. In contrast, the bacterial genus Cellulomonas, typically harmless but potentially an emerging pathogen, is more frequently found in the western parts of the country.
The primary factors influencing this airborne microbial landscape, according to Noah Fierer, a microbial ecologist at the University of Colorado and the study’s author, are the local types of soil and vegetation (which can affect environmental acidity) and climatic conditions (like humidity and temperature). Urban areas tend to share similarities in microbial composition, more so than neighboring rural areas, likely due to the uniformity in landscaping and common wildlife.
Fierer acknowledges that he faces challenges in interpreting the new map, as there is no historical data for comparison. Nevertheless, with this foundational work established, his team intends to embark on a larger-scale project that will employ filters attached to vehicles to collect air samples across vast areas. This initiative aims to shed light on the impact of airborne pathogens on human health, agriculture, livestock, and wildlife diseases.
While this research is pivotal, it won’t reveal exactly which microbes you’ve inhaled at any given moment. So, there’s no need to worry—take a deep breath, or perhaps just relax.