It is well established that air pollution can adversely affect lung and heart health — but how does air pollution affect our immune system?
A group of researchers from Canadian universities including the University of Toronto, the University of British Columbia, the University of Calgary, McGill University, and the University of Montreal recently investigated this, and published their findings in Rheumatology.
Autoimmune diseases occur when the immune system attacks the body’s own healthy cells, leading to chronic inflammation and damage to tissues and organs. Conditions such as rheumatoid arthritis, type 1 diabetes, lupus, psoriasis, and inflammatory bowel disease fall into this category and affect around 10% of the global population, with prevalence continuing to increase.
In Canada, autoimmune diseases like arthritis, Crohn’s disease, and multiple sclerosis are highly prevalent, and are a major burden on the healthcare system.
Systemic autoimmune rheumatic disorders (SARDS) are a subset of autoimmune diseases which primarily affect connective tissues, such as muscles and joints. These conditions may affect vital organs as well. This includes the heart, lung, liver, and kidneys.
Although previous research has shown that factors like genetic predisposition, chronic stress, and certain medications can contribute to the onset of autoimmune diseases, the question of whether environmental pollution contributes to the development of these types of disorders is less clear.
The authors focused on fine particulate matter, or PM2.5, which is air pollution caused by small inhalable particles with a diameter of 2.5 micrometers or less. Fine particulate matter can include liquid or solid droplets, such as biological matter like bacteria and pollen, or smoke from industrial waste.
The authors assessed whether exposure to fine particulate matter correlated with autoimmune conditions. They looked for ANA (antinuclear antibodies) positivity in the blood of the participants, which can be an early sign of SARDS.
The study used samples from the Ontario Health Study — which is part of the national CanPath project, and has collected biological samples from 41,000 participants in Ontario to study how environment, genetics, and lifestyle affect health. The authors randomly obtained blood samples from 3,548 participants that had consistently been living in the same postal codes for over 5 years.
The authors found that participants who were exposed to high levels of fine particulate matter were more likely to test positive for ANA in the blood. This means that exposure to air pollution may make individuals more susceptible to developing autoimmune conditions.
The study looked at the effect of air pollution on participants from wide age ranges and socioeconomic backgrounds. The authors found that female participants were more likely to be ANA positive than male participants: consistent with previous research showing that women are more likely to develop autoimmune conditions.
The results also showed that non-white participants were more likely to be impacted by air pollution. However, the random selection of participants led to under-representation of non-white participants in the study, with a majority of the participants being white.
Air pollution negatively impacts the health of Canadians every day. This study highlights how air pollution may adversely affect the immune system, in addition to the previously known impact on heart and lung health.
These findings underscore the need for strengthening air quality regulations, and reducing emissions of harmful pollutants.
