In a potentially worrisome development for those of us who breathe, chemists from the University of California, Irvine report that they’ve found fragments of fungal cells in the atmosphere. The pieces are extremely small, measuring about 30 namometers in diameter, and much more abundant that previously thought, the researchers said in a study published this week in Science Advances. https://advances.sciencemag.org/content/6/3/eaax9051. “These fragments are most likely bits of fungal spores which have burst after swelling with water,” said lead author Michael Lawler, assistant project specialist in the Ultrafine Aerosol Laboratory headed by coauthor James Smith, UCI professor of chemistry. “It was unexpected to see this many fungal parts of this size in the air, because aerosols of this nature are usually thought to be made from reactions of gases in the atmosphere, growing up from molecules rather than breaking down from larger particles.” Lawler said these lofted bits of fungus are easier to inhale deep into the lungs than intact cells which can measure thousands of nanometers in diameter. This means that the airborne particles can potentially act as a major contributor to allergic reactions and asthma among susceptible populations.

Another angle of the study explored the role these tiny crumbs of biological matter play in the formation of ice clouds. “Large, intact biological cells are extremely rare in the atmosphere, but we have identified fungal nanoparticles present at orders of magnitude higher concentrations, so if some or all of these are good ice nuclei, they could play a role in ice cloud formation,” he said. To make these discoveries, the researchers used a technique known as Thermal Desorption Chemical Ionization Mass Spectrometry in which they drew air into an inlet that size-selected ambient particles to take in only those measuring 20 to 60 nanometers in diameter. The samples were collected onto a thin platinum filament for 30 minutes and then vaporized; the resulting gases were detected using a high-resolution mass spectrometer. Danielle Draper, UCI undergraduate student in chemistry, participated in this study, funding for which was provided by the U.S. Department of Energy’s Office of Science.