Increased air pollution during winter months is linked to a rise in stroke-related Dublin hospital admissions, a new study has shown. The paper, published in the Cerebrovascular Diseases journal, by scientists from Trinity, the Royal College of Surgeons Ireland, and the HSE, has highlighted the public health implications of air pollution in cities around the world. Professor Brian Broderick from Trinity’s Civil, Structural and Environmental Engineering department was a co-author of the paper.
“These chemicals, upon inhalation, can affect blood pressure and heart rhythm, ultimately leading to blood clot formation and stroke.”
From 2013 to 2017, the team monitored the levels of certain air pollutants and number of daily hospitalisations due to all strokes and ischaemic strokes in Ireland’s two largest metropolitan areas, Dublin and Cork. Both cities also have a large number of air pollution monitoring sites, which were used for the research. The pollutants included in the study were fine and coarse particulate matter, ozone, nitrogen dioxide and sulphur dioxide. These chemicals, upon inhalation, can affect blood pressure and heart rhythm, ultimately leading to blood clot formation and stroke, should the clot interfere with the brain. These potentially harmful substances enter the air via domestic fuel burning (peat, coal and wood) as well as through road traffic emissions, particularly from diesel engines.
The authors do note, however, that sulphur dioxide levels have significantly reduced since the introduction of a smoky coal ban in Dublin and Cork cities. In July, the Green Party’s Eamon Ryan announced that this ban would be extended in September to include all towns with a population greater than 10,000, in the hope of further decreasing air pollution in Ireland.
Having incorporated variables like temperature, relative humidity, day of the week, and public holidays into their modelling, the team of researchers, led by Dr. Colm Byrne, found that there was a statistically significant increase in hospital admissions related to stroke in Dublin for up to two days after a rise in air pollution. Over the five years of the study, there were a total of 15,086 stroke cases, of which 10,830 were ischaemic strokes. In Dublin, increased amounts of nitrogen dioxide and sulphur dioxide in the air was associated with a 3.5% higher risk of suffering a stroke. Increased levels of coarse particles led to a 3.2% higher risk and an elevation in levels of fine particles in the air led to a 2.4% higher risk of suffering a stroke. In the less densely populated city of Cork, however, the team did not identify any significant association between hospital admissions for strokes and any individual air pollutant.
“Because Ireland has relatively low air pollution when compared internationally, this highlights the need to introduce additional policy changes to reduce air pollution in all countries.”
As this piece of research is the first to examine the relationship between individual air pollutants and strokes in Ireland, its findings have emphasised the urgency for policy measures to be implemented which aid in improving air quality during winter months in the capital. “Because Ireland has relatively low air pollution when compared internationally, this highlights the need to introduce additional policy changes to reduce air pollution in all countries,” says Prof David Williams of RCSI. The paper’s authors conclude with a call for both the ban of solid fuel combustion and for reductions in traffic on city roads. This, the study suggests, would help in lowering the occurrence of stroke in the population alongside much-needed positive environmental impacts.