Scientists are exploring links between urban air pollution and rising autoimmune disease rates.
Fine particles like PM2.5 are being studied for their effects on immune regulation.
Researchers are examining whether city living influences when autoimmune diseases begin and how severe they become.
Indian and global studies are helping clarify pollution’s role as a possible environmental trigger.
Practical steps are taken to reduce exposure in polluted cities.
Modern cities are hubs of innovation and opportunity, but there is an overlooked side to urban life that we're only beginning to understand. Beneath the vibrancy of city life lies a growing concern. Rising levels of air pollution, chronic environmental stressors, and sustained exposure to industrial byproducts are increasingly being examined not just for their respiratory or cardiovascular effects, but for their ability to alter immune function itself.
Autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, inflammatory bowel disorders, and autoimmune thyroid disorders have existed long before modern cities. The human immune system evolved in an environment vastly different from today’s polluted, densely populated urban landscapes, which is challenging immune regulation.
Urban living exposes individuals to a complex mixture of airborne pollutants originating from traffic emissions, construction activity, industrial processes, waste burning, and energy production. These pollutants are not encountered occasionally, but daily and cumulatively, often from early childhood onward.
Unlike acute infections, which provoke a short-lived immune response, chronic exposure to environmental pollutants can result in constant low-grade inflammation. Over time, this constant regulation can interfere with immune tolerance (the process by which the body learns to recognise its own cells). When this process is disturbed, the risk of autoimmune diseases increases. This mechanism lies at the heart of current research into environmental triggers of autoimmune disease.
Polluted air contains fine particulate matter (PM), which are microscopic particles that are small enough to penetrate deep into the lungs and enter the bloodstream. Once inside, they interact directly with immune cells. Continuous exposure to polluted air keeps the body in a state of low-grade inflammation. While inflammation is a natural response to injury or infection, persistent inflammation places the immune system under constant stress. Over time, this stress can increase the risk of immune cells behaving abnormally. Researchers also believe that certain pollutants can subtly alter the body’s own proteins. When this happens, the immune system may misidentify these altered proteins as threats and begin attacking them.
This is a key mechanism thought to contribute to autoimmune disease development. Among the most concerning components of urban air pollution are particulate matter, especially PM2.5 particles with a diameter of 2.5 micrometres or less. Due to their microscopic size, PM2.5 particles can penetrate deep into the lungs, enter the bloodstream, and reach organs far beyond the respiratory system.
Once inside the body, these particles can:
Activate inflammatory immune pathways
Generate oxidative stress
Disrupt immune cell signaling
Alter gene expression related to immune regulation
PM2.5 is considered particularly toxic because it often carries adsorbed heavy metals, organic chemicals, and combustion by-products, amplifying its biological impact.
Epidemiological studies from various parts of the world suggest that autoimmune diseases are being diagnosed with increasing frequency, particularly in urban and industrialised regions. While improved awareness and diagnostic assessments are partly responsible for this rise, they do not fully explain the observed patterns.
Studies comparing people living in cities and rural areas have found differences not only in the prevalence of autoimmune diseases, but also in the age at which they onset and their severity. These findings have led researchers to look more closely at environmental factors that may play a role. Within this broader trend, certain autoimmune conditions have shown particularly consistent associations with air pollution exposure, including rheumatoid arthritis, systemic lupus erythematosus, sclerosis, inflammatory bowel diseases, and autoimmune thyroid disorders.
In genetically susceptible individuals, chronic exposure appears capable of triggering earlier disease onset, while in those already diagnosed, polluted environments may accelerate symptoms and increase flare frequency. These findings support the view that exposure to polluted environments, along with genetic and immunological vulnerability, shape how autoimmune disease manifests over time.
Measures such as reducing outdoor exposure during peak pollution hours, using indoor air purification, and wearing high-quality masks in severe pollution can lower inhaled pollutant load. Lifestyle factors play a crucial role. Adequate sleep, stress regulation, regular physical activity, and anti-inflammatory dietary patterns can help support immune resilience.
India, in particular, has become a focal point for pollution-health research. Government led and academic projects across multiple Indian cities are now examining real world health impacts of air pollution beyond respiratory disease. These studies increasingly explore systemic inflammation, immune dysregulation, and long-term disease risk, including the role of PM2.5 toxicity patterns.
A study conducted at AIIMS, New Delhi, initially screened 1,500 residents, from whom 500 healthy adults who had lived in Delhi for over ten years and had no acute or chronic illness were selected for detailed testing. Researchers assessed participants for autoantibodies and inflammatory markers. The study found that 18% of individuals showed evidence of autoantibody positivity, while 68% had elevated inflammatory markers. Those living within 200 metres of major roads, indicating higher exposure to air pollution, showed significantly higher immune abnormalities. The findings suggest that long-term exposure to air pollution may trigger early immune system changes even before clinical disease appears.
They initiated the research to investigate the connection between autoimmune disorders and pollution in 2013. A total of 1,500 people were screened, and among them, 500 healthy individuals with no acute or chronic illnesses were tested for autoantibodies.
A comprehensive Pollution and Health monograph has also been issued to raise awareness among clinicians and researchers, emphasising that pollution’s effects extend far beyond the lungs, affecting cardiovascular, neurological, metabolic, and immune systems.
A large study by researchers at the University of Verona, published in RMD Open, found that long-term exposure to air pollution significantly increases the risk of autoimmune diseases. People exposed to higher levels of fine particulate matter like PM10 and PM2.5, commonly produced by traffic and power plants, showed notably higher risks, associated with a 40% increased risk of rheumatoid arthritis, a 20% higher risk of inflammatory bowel disease, and an overall 12–13% higher likelihood of developing autoimmune disease.
For many, relocating away from polluted urban centres is not a practical option. However, risk mitigation is possible.
Reducing outdoor exposure during peak pollution hours
Using indoor air purification
Wearing high-quality masks in severe pollution
Adequate sleep
Managing stress
Regular physical activity,
Anti-inflammatory dietary patterns
All these practices can help lower inhaled pollutant load and help support immune resilience. For individuals with existing autoimmune conditions, close disease monitoring during high-pollution periods and adherence to treatment plans become particularly important.
This information is not meant to scare anyone, but to help people understand what may be influencing their health. Knowing how environmental factors such as air quality affect the immune system allows individuals, doctors, and policymakers to make better choices.
While personal steps such as reducing exposure and staying healthy are important, larger improvements depend on cleaner energy, better urban planning, and strong public health policies. As cities grow, paying attention to how our surroundings affect immune health can help us reduce disease in the long run, rather than focusing on treatment only after the problems arise. In many ways, the immune system reflects how well we are living in the environments we have built.
Does air pollution cause autoimmune disease?
Current evidence suggests that long-term exposure to air pollution, especially fine particulate matter, may increase autoimmune disease risk by promoting chronic inflammation and immune dysregulation, particularly in genetically susceptible individuals.
What is PM2.5 and why is it dangerous?
PM2.5 refers to fine particulate matter measuring 2.5 micrometres or less. These particles can penetrate deep into the lungs, enter the bloodstream, and interfere with immune regulation, contributing to oxidative stress and inflammation.
Are autoimmune diseases more common in cities?
Studies indicate higher diagnosis rates, earlier onset, and increased severity of some autoimmune diseases in urban populations, likely reflecting combined effects of pollution exposure, lifestyle factors, and environmental stressors.
References:
Anna Bawden, “Air Pollution Linked to Higher Risk of Autoimmune Diseases,” The Guardian, March 15, 2022, accessed February 5, 2026, https://www.theguardian.com/environment/2022/mar/15/air-pollution-exposure-linked-higher-risk-autoimmune-diseases.
U. Kumar et al., “Prevalence of Pre-Clinical Autoimmunity in the Normal Adult …” PMC (PubMed Central), accessed February 5, 2026, https://pmc.ncbi.nlm.nih.gov/articles/PMC8133893/.
G. Adami et al., “Association between Long-Term Exposure to Air Pollution and Immune-Mediated Diseases: A Population-Based Cohort Study,” PMC (PubMed Central), accessed February 5, 2026, https://pmc.ncbi.nlm.nih.gov/articles/PMC8969049/.
“AIIMS Study Confirms Autoimmune Disorders Link with Air Pollution,” Times of India, March 2, 2020, accessed February 5, 2026, https://timesofindia.indiatimes.com/city/delhi/aiims-study-confirms-autoimmune-disorders-link-with-air-pollution/articleshow/79183935.cms.
Press Information Bureau (Government of India), “Press Release,” March 14, 2023, accessed February 5, 2026, https://www.pib.gov.in/PressReleasePage.aspx?PRID=1986209®=3&lang=2.
Press Information Bureau (Government of India), “Press Release,” November 20, 2024, accessed February 5, 2026, https://www.pib.gov.in/PressReleasePage.aspx?PRID=2093537®=3&lang=2.
McGill University Health Sciences, “Fine Particles pollution are associated with early signs of autoimmune disease,” accessed February 5, 2026, https://www.mcgill.ca/medhealthsci-research/article/fine-particles-pollution-are-associated-early-signs-autoimmune-disease.
Julie S. Park et al., “Association of Particulate Matter with Autoimmune Rheumatic Diseases,” PMC (PubMed Central), accessed February 5, 2026, https://www.sciencedirect.com/science/article/abs/pii/S1568997219300886.
Naizhuo Zhao, Audrey Smargiassi, Hong Chen, May Y. Choi, Marvin J. Fritzler, Zahi Touma, J. Antonio Aviña-Zubieta, and Sasha Bernatsky, “Fine Particulate Matter Air Pollution and Anti-Nuclear Antibodies,” Rheumatology 65, no. 1 (January 8, 2026): keaf545, https://doi.org/10.1093/rheumatology/keaf545.
