Fog is teeming with bacteria that eat pollutants and clean the air you breathe
Scientists at Arizona State University have found that fog droplets contain living, growing bacteria that actively break down harmful air pollutants like formaldehyde.
Fog has always felt like something between weather and mystery. It rolls in silently, blurs the edges of the world, and vanishes by morning.
But scientists at Arizona State University (ASU) have discovered something remarkable inside those tiny droplets: life.
A new study published in the journal mBio reveals that bacteria floating in fog droplets are not just surviving. They are actively growing, dividing and breaking down harmful pollutants in the air. In simple terms, fog is not just water suspended in air. It is a temporary, living ecosystem.
WHAT ARE BACTERIA DOING IN FOG?
Lead researcher Thi Thuong Thuong Cao, who was a PhD student at ASU during the project, focused on two questions: which bacteria live in fog, and are they actually active inside the droplets?
The answer to both was yes.
One bacterium stood out: methylobacteria. These microbes feed on simple carbon compounds, including formaldehyde, a common air pollutant linked to ozone smog and serious health risks. The bacteria were seen under a microscope, growing and dividing inside fog droplets, consuming formaldehyde as fuel.
At toxic levels, they also break it down into carbon dioxide, essentially protecting themselves while cleaning the air.
Interestingly, fewer than 1 per cent of fog droplets contain bacteria. Yet when all droplets are counted together, the concentration of bacteria equals that found in ocean water. A thimble of fog water contains roughly 10 million bacteria.
SHOULD WE STILL HARVEST FOG FOR DRINKING WATER?
Some communities already collect fog as a source of drinking water, assuming it is clean and safe. This study challenges that assumption. Fog should be treated and purified like any other water source before consumption.
There is also a bigger concern. If communities harvest fog on a large scale, they may be removing these air-cleaning microbes from the atmosphere. Whether that matters significantly is still unknown, but scientists say it must be studied.
WHY DOES THIS MATTER FOR CLIMATE SCIENCE?
Bacteria in clouds and fog could be reshaping our understanding of atmospheric chemistry. Unlike sunlight-driven chemical reactions, bacteria remain active even at night, potentially influencing air quality during hours when traditional chemistry slows down.
This could change how scientists model weather and climate.
As co-author Ferran Garcia-Pichel of the ASU Biodesign Center for Fundamental and Applied Microbiomics puts it: the sky’s the limit.
Fog has always felt like something between weather and mystery. It rolls in silently, blurs the edges of the world, and vanishes by morning.
But scientists at Arizona State University (ASU) have discovered something remarkable inside those tiny droplets: life.
A new study published in the journal mBio reveals that bacteria floating in fog droplets are not just surviving. They are actively growing, dividing and breaking down harmful pollutants in the air. In simple terms, fog is not just water suspended in air. It is a temporary, living ecosystem.
WHAT ARE BACTERIA DOING IN FOG?
Lead researcher Thi Thuong Thuong Cao, who was a PhD student at ASU during the project, focused on two questions: which bacteria live in fog, and are they actually active inside the droplets?
The answer to both was yes.
One bacterium stood out: methylobacteria. These microbes feed on simple carbon compounds, including formaldehyde, a common air pollutant linked to ozone smog and serious health risks. The bacteria were seen under a microscope, growing and dividing inside fog droplets, consuming formaldehyde as fuel.
At toxic levels, they also break it down into carbon dioxide, essentially protecting themselves while cleaning the air.
Interestingly, fewer than 1 per cent of fog droplets contain bacteria. Yet when all droplets are counted together, the concentration of bacteria equals that found in ocean water. A thimble of fog water contains roughly 10 million bacteria.
SHOULD WE STILL HARVEST FOG FOR DRINKING WATER?
Some communities already collect fog as a source of drinking water, assuming it is clean and safe. This study challenges that assumption. Fog should be treated and purified like any other water source before consumption.
There is also a bigger concern. If communities harvest fog on a large scale, they may be removing these air-cleaning microbes from the atmosphere. Whether that matters significantly is still unknown, but scientists say it must be studied.
WHY DOES THIS MATTER FOR CLIMATE SCIENCE?
Bacteria in clouds and fog could be reshaping our understanding of atmospheric chemistry. Unlike sunlight-driven chemical reactions, bacteria remain active even at night, potentially influencing air quality during hours when traditional chemistry slows down.
This could change how scientists model weather and climate.
As co-author Ferran Garcia-Pichel of the ASU Biodesign Center for Fundamental and Applied Microbiomics puts it: the sky’s the limit.
