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When we think of air pollution and children, we immediately worry about their lungs. Coughs, wheezing, asthma, respiratory infections and reduced lung function are among the first health concerns that come to mind. But could the damage go beyond what happens when a child breathes in polluted air?
Emerging research is raising questions about another possible casualty of toxic air: the gut.
Scientists are increasingly examining how exposure to fine particulate matter, particularly PM2.5, could alter the gut microbiome, affect the intestinal lining and trigger inflammation. There are also concerns about what these changes could mean for the immune system and the liver.
This is particularly relevant for children, whose gut microbiome, immune system and metabolic functions are still developing.
The gut is much more than a digestive organ. It houses trillions of microorganisms that help break down food, absorb nutrients, regulate metabolism and communicate with the immune system. Maintaining a healthy balance of these microorganisms is important. When this balance is disturbed, a condition known as dysbiosis, it can have consequences that extend beyond digestion.
How Does Dirty Air Reach The Gut?
It may seem unusual to link something we inhale with the health of our digestive system. However, the relationship between the lungs and the gut is an area of growing scientific interest.
When fine particulate pollutants enter the respiratory tract, they can trigger oxidative stress and inflammation. The body's inflammatory response may not remain confined to the lungs. It can have wider effects, potentially influencing the intestinal environment and the microorganisms living there.
Research is beginning to offer some clues.
A 2023 systematic review examining epidemiological, animal and laboratory studies found that exposure to particulate air pollution was generally associated with reduced gut microbial diversity in human population studies, alongside changes in the composition of gut bacteria.
A 2025 review published in Ecotoxicology and Environmental Safety further examined how PM2.5 exposure could influence gut physiology. It reported changes in gut microbial composition, reductions in certain beneficial short-chain fatty acid-producing bacteria and disruption of the intestinal barrier.
Short-chain fatty acids are important compounds produced by beneficial gut bacteria. They help maintain the intestinal lining and regulate inflammation. A reduction in these compounds, along with damage to the gut barrier, could potentially increase intestinal permeability and contribute to inflammatory responses.
For children, this deserves attention because the gut microbiome plays an important role in immune development, digestion and nutrient absorption.
Dr Neelam Mohan, Senior Director and HOD, Paediatric Gastroenterology, Hepatology & Liver Transplantation, Medanta - The Medicity, Gurugram, explains why this connection deserves closer examination. "The concern is not simply whether pollution causes digestive discomfort, but whether prolonged exposure can disturb the gut microbiome, trigger inflammation and affect the body's ability to maintain a healthy immune response."
In other words, the concern may go well beyond a child experiencing an occasional stomach-ache or digestive problem. Researchers are trying to understand whether repeated exposure to polluted air could influence the gut environment over a much longer period.
Could Your Child's Liver Also Be Affected?
There is another organ that deserves attention in this conversation: the liver.
The gut and liver are closely linked through what scientists call the gut-liver axis. The two organs communicate continuously. Nutrients and substances produced by gut bacteria are transported from the intestine to the liver through the portal circulation.
The gut lining acts as an important protective barrier. But when this barrier is compromised, certain bacterial products and inflammatory substances may pass into circulation and reach the liver.
This is one reason why changes in gut health can have implications for liver health.
Research into environmental pollution has also explored possible associations between exposure to air pollutants, metabolic disturbances, liver inflammation and fat accumulation in the liver.
For children, this is an important area of investigation, particularly as childhood obesity and metabolic dysfunction-associated steatotic liver disease (MASLD), commonly known as fatty liver disease, are growing health concerns.
Dr Mohan points to the interconnected nature of these systems. "Children's liver health cannot be viewed in isolation from their gut health, nutrition and environmental exposures. The gut microbiome, immune system and liver function are interconnected, and disturbances in one system may have implications for the others."
It is important to remember that the science is still evolving. There is not yet sufficient evidence to establish that air pollution directly causes fatty liver disease in children through changes in the gut microbiome. However, the gut-liver connection provides an important reason to investigate the wider effects of environmental exposure.
The numbers make this a bigger concern for India. Children are particularly vulnerable to air pollution because their bodies are still developing, they breathe more air relative to their body weight than adults and they often spend time outdoors.
The scale of exposure is worrying.
According to the WHO's 2018 report on air pollution and child health, 93% of children under 15 worldwide were living in environments where air pollution exceeded WHO guideline levels.
A 2024 study published in The Lancet Regional Health - Southeast Asia, analysing data from 224,214 Indian children under five, found a significant association between higher PM2.5 exposure and respiratory illness.
The median annual PM2.5 exposure among the children studied was 63.4 micrograms per cubic metre, considerably higher than India's annual national standard of 40 micrograms per cubic metre.
While these figures primarily highlight respiratory risks, they also underline the scale of environmental exposure during some of the most important years of a child's development.
Is Pollution Also Affecting The Brain And Gut Microbiome?
Clinical nutritionist Ishi Khosla believes we need to look at pollution through a much wider health lens, particularly when it comes to children. She draws attention to research from Mexico City, where scientists have investigated the possible neurological effects of prolonged exposure to severe air pollution.
Ishi says, "Pollution affects the gut and the brain in young children. It is important to address this as an urgent matter. Studies in Mexico City have reported concerning changes in the brains of children exposed to high levels of air pollution, including changes involving the frontal cortex."
She also highlights the possible role of the gut microbiome in this process. "Pollution that we inhale can disturb the microbiome and lead to dysbiosis, increasing the presence of unfriendly microorganisms. Lipopolysaccharides, which are components of the outer membrane of certain bacteria, can contribute to inflammation and compromise the gut barrier. This is what we refer to as a leaky gut. There are also concerns about how inflammatory processes could affect the brain."
Can The Right Diet Support A Child's Gut Health?
If polluted air can influence the gut microbiome, can nutrition help?
The first thing to remember is that food cannot neutralise toxic air or reverse the effects of prolonged pollution exposure. Improving air quality and reducing exposure remain the most important interventions.
However, nutrition can play a meaningful supporting role in maintaining gut health and normal immune function.
A diet with plenty of fibre, diverse plant foods and naturally fermented foods can help nourish beneficial gut bacteria. Fruits, vegetables, whole grains, millets, pulses, nuts and seeds are all useful additions to a child's diet.
Ishi Khosla believes that traditional Indian foods have a place in this conversation. Her advice is to focus on dietary diversity rather than relying on a single superfood. "Children can have a small piece of gur (jaggery) as part of a balanced diet. A diet rich in probiotics and fibre is a good one. Include whole grains, preferably millets and rice, along with fermented foods such as ambli, rice water, kanji and other naturally fermented preparations."
The larger nutritional message is to build a diet that supports a healthy microbiome through adequate fibre, variety and appropriate fermented foods.
The bigger concern: Children's health cannot be measured by their lungs alone
For years, the conversation around air pollution and children has largely focused on respiratory illnesses. And rightly so. The impact on lung development, asthma and respiratory infections is well established.
But the emerging research is encouraging scientists to ask bigger questions.
Could prolonged exposure to polluted air influence the gut microbiome? Could changes in the gut barrier contribute to inflammation? Could the gut-liver axis be another pathway through which environmental exposure affects children's metabolic health?
We do not have all the answers yet. But these are questions worth investigating, particularly in countries like India, where millions of children grow up breathing polluted air.
For parents, the practical message is to pay attention to overall health. Encourage a varied, fibre-rich diet, include appropriate fermented foods, ensure good nutrition and take steps to minimise children's exposure to polluted air.
Because protecting children from pollution should not simply be about helping them breathe easier today. It should also be about safeguarding the systems that support their growth, immunity and health for years to come.
Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.