ATLANTA—Anti-citrullinated protein antibodies (ACPA) are a characteristic finding in rheumatoid arthritis (RA). A study investigating the effect of common industrial pollutants on ACPA found a significant correlation between industrial fine particulate matter exposure and ACPA positivity, according to findings presented at the 2019 ACR/ARP Annual Meeting.1
In a previous study, the investigators reported on the effects of individuals’ proximity to major industrial emitters and individual industrial air emissions, such as sulfur dioxide and fine particulate matter.2 These emissions were associated with an increased probability of ACPA positivity in a general population sample. To further investigate air pollutant exposure, the investigators expanded the sample size in their latest study and investigated simultaneous exposure to multiple air pollutants.
“It’s important to consider joint effects of different air pollutants because these pollutants often come from the same sources, such as road traffic and factories, and concentrations of these pollutants are usually correlated in space,” says Sasha Bernatsky, MD, PhD, senior scientist and James McGill professor in the Centre for Outcomes Research and Evaluation at McGill University, Montreal, Canada. For the past decade, she and her colleagues have been studying air pollutants and the effects on human health.
Multiple Air Pollutants & Immune Health
To better understand the effects of multiple air pollutants on ACPA positivity, Dr. Bernatsky and her colleagues determined serum ACPA for 7,600 randomly selected general population subjects in Quebec, Canada. They estimated associations between ACPA and measures of industrial sulfur dioxide, nitrogen dioxide and fine particulate matter concentrations, using sophisticated statistical modeling to account for the simultaneous exposure to these multiple pollutants. Fine particulate matter had the most significant association with ACPA positivity, seen with both single-exposure and multi-exposure regression models with sulfur dioxide. However, no clear associations for nitrogen dioxide were found.
Particulate matter in air pollution is made of solid and liquid particles suspended in the air. Particulate matter smaller than 2.5 μm in diameter is considered fine and is small enough to enter the lungs through breathing. Once in the lungs, this fine particulate matter can pass into the blood supply and stimulate immune cells, triggering systemic autoimmune responses that may cause the development of autoimmune rheumatic disease, Dr. Bernatsky explains. She notes that fine particulate matter comes from many sources, including cars, industries that burn fossil fuel and natural processes, such as forest fires.
Air Pollution Data & Patients Education
It’s too early to know how best to use air pollutant data practically to influence patient care. But Dr. Bernatsky says data from her and her colleagues’ research are helpful to regulators and health policymakers who advocate for cleaner air and have created tools to measure pollution, such as a real-time, worldwide, online air quality index. Often, these tools are used by local health authorities and agencies to help advise patients with asthma, autoimmune rheumatic disease and other conditions whose health may be affected by poor air quality.