On May 14, 2026, researcher Thi Thuong Thuong Cao as a PhD student at Arizona State University (ASU) found that a foggy field in Pennsylvania has a little secret — its suspended water droplets form a habitat for helpful bacteria that eat air toxins.

The team found that fewer than 1% of fog droplets contain bacteria. But averaged together, they represent an astounding amount of life.

“When you take all of the droplets together, the concentration of bacteria is the same as in the ocean,” says Garcia-Pichel, also a Regents Professor in the ASU School of Life Sciences. A thimble’s worth of fog water has some 10 million bacteria.

One group of bacteria stood out: methylobacteria. Samples of dry air collected before fog events contained less of these bacteria than samples collected immediately after. That suggests fog briefly boosts their numbers.

Methylobacteria eat simple carbon compounds, which include nasty chemicals like formaldehyde. Formaldehyde is a common pollutant that adds to ozone smog and harms human health.

Fog samples Cao collected in the field and lab experiments showed what these bacteria are doing inside fog droplets.