New Delh:- A new study has found that prolonged exposure to fine particulate matter, or PM2.5, is associated with increased disease activity and a higher risk of flare-ups in people with rheumatoid arthritis.
The study, published in the journal Annals of the Rheumatic Diseases, tracked more than one thousand rheumatoid arthritis patients across over twelve thousand outpatient visits in South Korea between 2021 and 2024.
Researchers from Seoul National University College of Medicine examined exposure to six major air pollutants. They found that PM2.5 was significantly associated with higher disease activity and an increased risk of rheumatoid arthritis flare-ups.
The association was more pronounced among women and non-smokers. The study also found that cumulative exposure to PM2.5 for more than two weeks was linked to a greater risk of disease flare-ups.
Researchers said PM2.5 particles can enter the bloodstream from the lungs and trigger oxidative stress and inflammatory responses in the body.
The lead researcher, Eun Bong Lee, recommended that rheumatoid arthritis patients avoid prolonged exposure to poor air quality, particularly during periods of high PM2.5 levels. The researchers said further studies are needed to determine whether improving air quality can directly reduce disease activity.
Air pollution exposure was estimated using monthly concentrations of six major air pollutants — sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), PM10 and PM2.5 — which were matched with disease activity and flare outcomes recorded at each outpatient visit. PM2.5 was identified as a key contributor to increased disease activity in rheumatoid arthritis.
“Among (the) six pollutants, PM2.5 was significantly associated with an increased risk of flare and with (a) higher Disease Activity Score based on 28 joints (DAS28) with C-reactive protein (CRP), Clinical Disease Activity Index, 28-tender joint count, and 28-swollen joint count,” the authors wrote. “In addition, the association between PM2.5 and DAS28-CRP was more pronounced among women and nonsmokers,” they said.
Further, a prolonged cumulative exposure to PM2.5 over more than two weeks was associated with an increased risk of flare in rheumatoid arthritis. “Our study has important implications for public health policy making.
While further studies are warranted to determine whether improving air quality can reduce disease activity in RA (rheumatoid arthritis) patients, we would recommend these patients avoid prolonged exposure to poor air quality, particularly high PM2.5 levels,” lead researcher Eun Bong Lee, from the department of internal medicine, Seoul National University College of Medicine, said.
Being smaller than red blood cells in size, PM2.5 particles can easily travel from the lungs into the bloodstream, circulating to distant organs. The particles can then trigger the overproduction of harmful molecules called reactive oxygen species, thereby inducing cellular stress, damaging DNA, and sparking inflammatory responses in organs, the researchers explained.
In an accompanying editorial, Jeffrey A. Sparks, from the division of rheumatology, inflammation, and immunity at Mass General Brigham / Brigham and Women’s Hospital, and Harvard Medical School in the US, and not involved with the study, said, “This is one of the largest studies to use robust methods to link air pollutants with RA disease activity.”
Sparks added that the study has significant clinical, biologic, and public health implications, given the increasing levels of air pollutants, and further reinforces that inhalants may have broad implications for risk and progression of RA and other autoimmune diseases.
“From a clinical perspective, this may offer avenues to lower the risk of RA flares by avoiding air with poor quality and provide some potential explanation for otherwise idiosyncratic RA flares,”
