Air pollution may be harming far more than the lungs and heart. A new study published in the journal Scientific Reports has found that exposure to fine particulate matter, or PM2.5, significantly increases the risk of hospitalisation for several kidney diseases, raising fresh concerns over the hidden systemic impact of urban air pollution.
It said pollution levels currently considered acceptable under international guidelines too can be harmful to kidney health.
The study analysed pollution exposure and kidney disease-related hospitalisations in São Paulo, Brazil, between 2011 and 2021. Researchers found that even relatively low concentrations of PM2.5 were associated with increased hospitalisation risk, particularly among men.
PM2.5 refers to microscopic particles smaller than 2.5 micrometres generated largely through vehicle emissions, fossil fuel combustion and industrial pollution. Because of their extremely small size, these particles can penetrate deep into the lungs and eventually enter the bloodstream, triggering inflammatory damage across multiple organs.
According to the study, PM2.5 concentrations in São Paulo reached as high as 65 micrograms per cubic metre during the study period — more than four times the 24-hour exposure limit of 15 micrograms per cubic metre recommended by the World Health Organization. However, researchers warned that even pollution levels falling within WHO’s recommended threshold were associated with increased kidney-related hospitalisations.
“Even concentrations within the limit showed a link to hospitalisations for kidney diseases, indicating the need to intensify policies to reduce air pollution,” said Iara da Silva, the study’s lead author.
The findings are particularly worrying because kidney disease often progresses silently for years before symptoms become clinically apparent. Researchers found that long-term exposure to high PM2.5 levels increased the risk of chronic kidney disease by up to four times across different age groups.
Men appeared especially vulnerable. The study reported significantly higher hospitalisation risks for acute kidney injury and glomerulopathies — disorders affecting the kidney’s microscopic blood-filtering structures — among younger and middle-aged men exposed to higher particulate concentrations.
Exposure to pollution levels ranging between 15 and 65 micrograms per cubic metre was also associated with increased cumulative risk of membranous nephropathy, a serious kidney disorder that may eventually progress to kidney failure.
Scientists believe the mechanism may involve direct inflammatory injury caused after particulate matter enters the bloodstream and accumulates within kidney tissues.
Lucia Andrade, one of the researchers involved in the study, explained that particulate matter may trigger immune responses, inflammation, fibrosis and premature cellular ageing within the kidneys.
“The hypothesis is that particulate matter can enter the bloodstream and deposit in kidney tissue, where it is recognised by the immune system as a foreign body,” she said.
Previous experimental research conducted by the same group on laboratory animals found that exposure to polluted air worsened kidney injury, reduced filtration capacity and increased tissue inflammation and fibrosis.
The findings add to growing global evidence suggesting that air pollution is not merely a respiratory hazard but a multi-organ public health threat capable of affecting the cardiovascular, neurological, metabolic and renal systems.
For India, the implications may be particularly serious. Several Indian cities, including Delhi and large parts of the National Capital Region, continue to record PM2.5 concentrations far exceeding WHO safety standards for prolonged periods every year. Public health experts warn that pollution may now be emerging as an additional and under-recognised contributor to India’s already rising burden of chronic kidney disease.
India already faces a substantial burden of kidney disorders driven by diabetes, hypertension, lifestyle changes and delayed diagnosis. When contacted, Dr. Vikram Kalra, Principal Director, Nephrology & Kidney Transplant at Aakash Healthcare, concurred with the study findings.
“Prolonged exposure to fine particulate air pollution, especially PM2.5 pollutants, can enter the bloodstream through the respiratory system and trigger chronic inflammation, oxidative stress, and damage to blood vessels,” Dr. Kalra told The Health Outlook.
He further added that over time, this may reduce kidney function and increase the risk of chronic kidney disease, particularly in people with diabetes, hypertension, or pre-existing kidney conditions.
Dr. Kalra stressed that urban populations, traffic police personnel, industrial workers and individuals living in highly polluted areas remain especially vulnerable.
“Protecting kidney health today also means reducing long-term exposure to environmental pollutants. Staying hydrated, monitoring blood pressure and blood sugar levels, and minimising exposure to polluted environments are important preventive measures,” he said.
