Link between pollution and disease requires world to ‘sit up and take notice’

The indication of a link between air pollution and autoimmune diseases should make the world "sit up and take notice", a leading specialist in inflammatory bowel disease (IBD) based in Ireland has said.

Prof Subrata Ghosh, an expert in IBD, Crohn's disease and ulcerative colitis at APC Microbiome Ireland in UCC, said the link suggested by Italian researchers, was particularly significant in the context of such diseases increasing globally.

This was especially the case in newly-industrialised countries such as China, he said, due to changes in lifestyle and diet including increased consumption of processed food and fast food.

But the air pollution factor was increasingly featuring in research. “This particular study raises that issue once again which is good,” Prof Ghosh said.

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He was particularly interested because IBD, notably ulcerative colitis, is often a disease of young people.

As it was a population study suggesting an association rather than demonstrating cause and effect, it was inevitably subject to bias, he added. However, it underlined the need for further research, especially to identify a possible mechanism leading to IBDs, he said.

Air pollution expert Dr Clare Noone of Maynooth University, said it "adds to the already mounting evidence that air pollution – the majority of which comes from our dependence on fossil fuels – is a major global public health concern".

In 2021, the World Health Organisation urged countries to tackle dirty air to save millions of lives worldwide.

“Here in Ireland, it is estimated that approximately 1,300 premature deaths per year are due to poor air quality from particulate matter (PM). The two main sources of PM in Ireland are burning of coal, peat, wood for home heating and emissions from vehicles in urban areas,” she noted.

PM levels were a concern in Ireland, she said, with the EPA in 2020 reporting levels in 50 per cent of monitoring stations that were above WHO air quality guidelines.

“Decarbonising transport, with a move towards walking, cycling, public transport, and electric vehicles and retrofitting our homes are win-wins for air quality and climate change,” Dr Noone said.

She welcomed some positive action, notably with Dublin becoming the first Irish city to sign up to the WHO Breathe Life campaign. “Hopefully, other towns and county councils in Ireland will follow suit,” she added.

Prof Gaye Cunnane, a rheumatologist at St James's Hospital, Dublin, said: "Although the cause of autoimmune disease is unknown, it is thought to be due to 'environmental' exposure in genetically susceptible people...We know those with the HLA-DRB1 gene are more likely to develop RA [rheumatoid arthritis], but the associated environmental factors have, to date, proven elusive."

There is, however, emerging evidence of the role of air pollution in the initiation and exacerbation of autoimmune disease, she confirmed. “It has been known for decades that cigarette smoking is associated with RA – people who smoke are more likely to develop joint inflammation, to have a more severe form of the disease and to have a reduced response to treatment.”

More recently, reports of air pollution effect on autoimmune disease, through similar mechanisms described for cigarette smoking, were emerging.

“Levels of inflammation are increased in people who live on busy urban roads compared with those who reside in rural settings. In addition, air pollution can prevent adequate skin exposure to sunlight and reduce vitamin D formation. Low levels of this vitamin are also associated with autoimmune disorders,” Prof Cunnane added.

“Chronic inflammation is harmful to the body because it results in continual cell damage, persistently high levels of proinflammatory cytokines, along with genetic alterations, thus harbouring an environment where auto antibodies can orchestrate widespread destruction,” she explained.

The Italian study found significant correlation between particulate matter in the atmosphere and prevalence of autoimmune disorders, but participants were mostly older women selected from a fracture database, and so were already vulnerable to ill-health, she noted.

“Although the findings cannot necessarily be extrapolated to the wider population, they nevertheless substantially add to the existing information about the harms caused by air pollution and toxic inhalants, and the need to mitigate the associated health risks,” she said.