Are autoimmune diseases such as rheumatoid arthritis, where the body’s immune system reacts against itself, linked to air pollution?
A preliminary analysis of an ongoing study at AIIMS since April 2013 on 300 rheumatoid arthritis patients has found their symptoms worsen when suspended particulate matter (SPM) 2.5 increases in the atmosphere.
Particulate matter are essentially pollutants in the air, microscopic solid or liquid particles suspended in the atmosphere. Depending on their size, the pollutants are classified into many subtypes, one of them being SPM 2.5. It includes particulate matter less than 2.5 micrometres in diameter.
“These are preliminary findings, where we have found a definite co-relation between increase in one category of pollutants, that is PM 2.5, and the symptoms in diagnosed rheumatoid arthritis patients. Patients showed worsening of symptoms like joint pain and swelling when the air pollutants increased,” Dr Uma Kumar, head of Clinical Immunology and Rheumatology department and principal investigator of the study, said.
The study, funded by the Department of Science and Technology as part of a project on climate change, is being jointly conducted by the Rheumatology department at AIIMS and the Indian Meteorological Department (IMD). The study is expected to take two more years.
Studies in the US and Sweden have found a minor link between rheumatoid arthritis and vehicular pollutants like nitrogen dioxide and home-heating pollutants like sulphur dioxide, but no association between the disease and suspended particulate matter in the atmosphere.
Researchers from McGill University Health Centre in Canada have found that “short-term variations in air pollution may influence disease activity” in patients of Lupus disease, another autoimmune disorder.
Dr Kumar too said there could be a “potential link” between air pollutants and other autoimmune disorders, which warranted studying.
Dr Kumar said, “Till now, we have analysed the condition of the patients through last year with data taken retrospectively on air pollutant levels from IMD. Now, a prospective study will be done on the same patients, collecting current data and comparing their symptoms.”
“We will start by collecting current data from IMD from Diwali when air pollutant levels shoot up and analyse the condition of patients. We will analyse pollutant levels in four categories and see the corresponding symptoms till 2016 in our identified patients,” Dr Kumar said.
This, she said, would provide a more accurate and detailed analysis on the connection.
Researchers are in the process of analysing co-relations between the symptoms and other category of pollutants, including SPM 10, sulphur dioxide and nitrogen dioxide. “The preliminary findings already indicate a connection with SPM 2.5, but we are analysing other environmental pollutants too to establish if they are related to the symptoms,” Dr Kumar said.