According to a study, prolonged exposure to air pollution is connected to an increased risk of autoimmune disorders, notably rheumatoid arthritis, connective tissue diseases and inflammatory bowel diseases. The study was published in the open-access journal RMD Open.
Adaptive immunity — how the body responds to a specific disease-causing entity — can be triggered by environmental air pollution from car emissions and industrial production. However, this adaptive response can go wrong, resulting in an inflammatory process, tissue damage and, eventually, autoimmune diseases.
Rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel illnesses — such as ulcerative colitis, connective tissue disease — such as osteoarthritis, and multiple sclerosis are all examples of autoimmune disorders.
The frequency and severity of these diseases have progressively climbed over the last decade, for reasons that are not completely obvious. According to the researchers, whether air pollution is associated with an increased risk of autoimmune illness is still up for debate.
The researchers searched the national Italian fracture risk database (DeFRA) and collected full medical records on 81,363 men and women provided by more than 3500 clinicians between June 2016 and November 2020 to try to cast some light on this topic.
The majority of the participants were women (92%) with an average age of 65, and 17866 (22%) had at least 1 pre-existing medical condition.
Using their residence postcode, each participant was routed to the closest air quality measurement station maintained by the Italian Institute of Environment Protection and Research.
The potential influence of particle matter was of special interest to researchers (PM10 and PM2.5). PM10 levels of 30 µg/m3 and PM2.5 levels of 20 µg/m3 are typically considered hazardous to human health.
Between 2016 and 2020, 9723 individuals (12%) were identified with an autoimmune condition.
Air quality data was collected from 617 monitoring stations across 110 Italian regions. Between 2013 and 2019, the average prolonged exposure for PM2.5 was 16 µg/m3 and 25 µg/m3 for PM10.
PM2.5 exposure was not linked to an increased chance of being diagnosed with an autoimmune illness. After accounting for potentially major factors, however, every 10 µg/m3 increase in PM10 levels was related to a 7% increased risk.
Long-term exposure to PM10 levels greater than 30 µg/m3 and PM2.5 levels greater than 20 µg/m3 were linked to a 12% and 13% greater risk of autoimmune illness, respectively.
Long-term exposure to PM10 was linked to an increased risk of rheumatoid arthritis, whereas long-term exposure to PM2.5 was linked to an increased risk of rheumatoid arthritis, connective tissue disease and inflammatory bowel disease.
Prolonged exposure to traffic and industrial air pollution was linked to a 40% increase in the chance of rheumatoid arthritis, a 20% increase in the risk of inflammatory bowel disease and a 15% increase in the risk of connective tissue illnesses.
Since this is experimental research, it is impossible to establish cause. Furthermore, the researchers note several limitations that may have influenced their findings.
The lack of facts on the dates of diagnosis and the onset of autoimmune disease signs, the possibility that air quality monitoring does not reflect personal exposure to pollutants; and the possibility that the findings are not more broadly applicable since the study participants were mostly older women at risk of fracture.
However, researchers point out that air pollution has been related to immune system deformities, and that smoking, which carries some toxins with fossil fuel emissions, is a risk factor for rheumatoid arthritis.
Adami, G., et al. (2022) Association between long-term exposure to air pollution and immune-mediated diseases: a population-based cohort study. RMD Open. doi.org/10.1136/rmdopen-2021-002055.