Did you know fog contains bacteria that can eat pollutants and clean the air? New study reveals

A team of researchers from Arizona State University (ASU) and Susquehanna University has uncovered that fog droplets harbor dense populations of metabolically active bacteria, particularly *Methylobacterium* species, which can degrade harmful pollutants such as formaldehyde. The study, published in *mBio* in May 2026, analyzed 32 radiation fog events over two years in Pennsylvania, revealing that while fewer than 1% of droplets contain bacteria individually, the total microbial load rivals concentrations found in oceans and lakes. Lead researcher Thi Thuong Thuong Cao, who conducted the work during her PhD at ASU, investigated whether bacteria in fog droplets are active rather than merely suspended. Co-author Ferran Garcia-Pichel, director of the ASU Biodesign Center for Fundamental and Applied Microbiomics, noted this discovery challenges the traditional view of fog as inert water particles, suggesting droplets may serve as microbial habitats. Assistant research scientist Soumyadev Sarkar linked microbial physiology to genomics, identifying *Methylobacterium* strains’ potential to assimilate formaldehyde via the serine cycle and a possible photoheterotrophic lifestyle supported by bacteriochlorophyll synthesis. The findings imply fog harvesting—already explored as a freshwater source in water-scarce regions—may require treatment due to pathogenic bacteria. Beyond atmospheric science, the study suggests microbial activity in fog droplets could influence climate and atmospheric chemistry models. Researchers caution that while fog bacteria may clean air by breaking down pollutants, its use as a water source demands further safety assessment due to high microbial loads.