Exposure to dust, soot and smoke may increase flare-ups in those living with rheumatoid arthritis, a study has found.

Around 400,000 to 700,000 people in the UK are thought to have the condition, which sees the body attacking healthy joint tissue, causing pain, swelling, warmth and stiffness in the hands, wrists and feet.

Previous research suggested that air pollution may increase the risk of developing rheumatoid arthritis but less is known about its impact on people who already have it.

The study, published in the Annals of the Rheumatic Diseases journal, found higher levels of air pollution were associated with worsening symptoms in those who already had the disease.

Researchers say the findings highlight the importance of considering environmental factors as part of long-term disease management.

Scientists in South Korea followed 1,070 patients with rheumatoid arthritis over four years, analysing data from more than 12,500 outpatient visits between 2021 and 2024.

They compared patients' disease activity with estimated exposure to six common air pollutants, including sulphur dioxide and carbon monoxide.

The study found that tiny pollution particles from traffic and factories were most strongly linked to flare-ups in sufferers.

Lead investigator Eun Bong Lee, from the Department of Rheumatology at Seoul National University Hospital, said: 'Our study has important implications for public health policymaking.

'While further studies are warranted to determine whether improving air quality can reduce disease activity, we recommend these patients avoid prolonged exposure to poor air quality.'

Outdoor air pollution in the UK is linked to an estimated 40,000 early deaths each year, according to the Royal Colleges of Physicians and of Paediatrics.

London is widely recorded as the UK's most polluted major metropolitan area. However, towns such as Port Talbot and Scunthorpe have high levels.

Previous analysis has established links between pollution and various conditions, including heart attacks, strokes, asthma, type 2 diabetes, obesity and dementia.