A new study from China has found that exposure to common air pollutants may significantly increase the risk of liver damage among older adults.
The research, conducted in Xiamen City, followed more than 23,000 adults aged 65 and older who were living with metabolic dysfunction-associated steatotic liver disease (MASLD).
Sometimes called fatty liver disease, MASLD affects roughly 30% of the global population and can progress to liver fibrosis, a type of scarring that raises the risk of cirrhosis and liver cancer.
Researchers measured long-term exposure to ozone, carbon monoxide, sulfur dioxide, PM2.5 and PM10. They then analysed how those exposures related to the severity of liver fibrosis among participants.
They found that people exposed to the highest levels of PM10 were almost twice as likely to develop liver fibrosis compared to those with the lowest exposure. Elevated levels of ozone, carbon monoxide, sulfur dioxide and PM2.5 also increased risk, though to a slightly lesser extent. Among all the pollutants studied, PM10 emerged as the strongest driver of liver damage.
When researchers looked at the combined effects of multiple pollutants, the picture grew more concerning. Exposure to a mix of pollutants significantly raised the likelihood of liver fibrosis, reinforcing the idea that people are rarely affected by a single pollutant in isolation.
Older adults who did not engage in regular physical activity faced higher risks of liver fibrosis when exposed to the same pollutant levels as their more active peers. The findings echo earlier research suggesting that physical activity can buffer the body against some of the harm caused by polluted air, even if exercise itself increases breathing rates and pollutant intake in the short term.
Scientists believe several biological pathways may explain the connection. Pollutants can generate excess free radicals, leading to oxidative stress that damages liver cells. They can also disrupt the body’s ability to process fats and sugars, fueling the progression of fatty liver disease. In addition, pollutants are known to trigger chronic inflammation, which accelerates scarring in the liver.
The findings come at a time when populations in China and many other countries are rapidly aging. Because MASLD becomes more common with age, experts warn that rising pollution levels could combine with demographic shifts to create a significant public health burden.
The authors said: ‘This study highlights the importance of reducing air pollution exposure in managing and potentially slowing the progression of liver fibrosis in older adults with MASLD.’
The full research can be read here.