Living in a bustling polluted city could raise the risk of an autoimmune condition affecting 50,000 Britons, alarming research has suggested.
Scientists have long tried to unpick what exactly triggers systemic lupus erythematosus, more commonly known as lupus, to occur.
The condition, which is also suffered by Selena Gomez, Lady Gaga and Nick Cannon, sees the body's immune system mistakenly attack healthy tissue.
But researchers in China now believe long-term exposure to air pollution 'may increase the risk of developing lupus'.
Dr Yaohua Tian, an expert in air pollutants and chronic disease at Huazhong University of Science and Technology and study co-author, said: 'Our study provides crucial insights into the air pollution contributing to autoimmune diseases.
'The findings can inform the development of stricter air quality regulations to mitigate exposure to harmful pollutants, thereby reducing the risk of lupus.'
Patients with the condition often experience flare-ups where symptoms like joint and muscle pain, extreme fatigue and rashes get worse.
These episodes can last for weeks or longer.
In the new study, the Chinese researchers followed 460,000 patients and found 399 people were diagnosed with lupus over a 12 year period.
Average levels of six pollutants close to their homes were also assessed.
These included PM2.5 — which stands for particulate matter less than 2.5 micrometers in diameter — nitrogen dioxide (NO2), nitric oxide (NOx) and sulfur dioxide (SO2).
All four have been linked to health woes such as heart disease and dementia.
These particles, emitted by car exhausts, cleaning products and wood-burning stoves, among many other things, can be so small they travel deep into the lungs and bloodstream.
The researchers there was one in 1,000 risk of lupus among those exposed to the highest levels of NO2, and just 0.075 in 1,000 risk in those exposed to the lowest levels.
This trend was reflected among all three other particles.
Writing in the journal, Arthritis and Rheumatology, the scientists said the results provide 'crucial insights into the environmental factors contributing to autoimmune diseases'.
They added: 'Findings can inform the development of stricter air quality regulations to mitigate exposure to harmful pollutants, thereby reducing the risk of lupus.'
Researchers, however, acknowledged the study had 'certain limitations' including the study's participants enrolling voluntarily.
This means they 'may have been healthier, more health conscious or more willing to participate in the study, they added.
The World Health Organization has long demanded countries take tougher action to combat the scourge of pollution, which is thought to kill 7million people every year globally.
It comes as separate research today revealed US scientists had discovered a molecular defect they believe may trigger lupus.
These changes in molecules in the blood of lupus patients, means the aryl hydrocarbon receptor (AHR), which regulates cells' response to pollutants and bacteria, is not activated properly.
Dr Deepak Rao, study co-author and an assistant professor of medicine at Harvard Medical School, said: 'We've identified a fundamental imbalance in the immune responses that patients with lupus make, and we’ve defined specific mediators that can correct this imbalance to dampen the pathologic autoimmune response.'
According to Lupus UK, about one in every 50,000 people in the UK have the condition.
There is no cure for lupus with treatment instead designed to help people manage their symptoms.
Lupus can range from mild, when it causes skin or joint problems to severe where it can cause life- threatening to organs.
Flare-ups, periods where symptoms get worse are another aspect of the condition scientists are still trying to understand.
Both what triggers them and what causes them to subside isn't yet clear.
Further complicating the topic is that some patients don't experience flare-ups at all.
