Air Pollution Risk Factor For Brain Strokes, Similar To Smoking: Study

“Our study has made an important discovery. It has shown that particulate matter air pollution is responsible for 2.6 million healthy life years lost due to death and disability from subarachnoid haemorrhage in 2021, which is one million more than that from smoking, another major risk factor for SAH,” Professor Valery Feigin, Director, National Institute for Stroke and Applied Neurosciences, Auckland University of Technology, New Zealand, and lead author of the study told The Indian Express via email.

He said pollutants like PM2.5 damage the arterial cells, thus increasing the chance of rupture. “Just for the illustration of what 2.5 microns is — it is about 30 times thinner than a human hair. These tiny particles likely affect the arterial cells — damaging them directly or indirectly (e.g., via inflammation) with resulting weakening of the arterial wall and its rupture leading to subarachnoid haemorrhage (SAH),” Valery explained.

The study also revealed that the risk of strokes from high temperatures, or heat, had increased by more than 70% between 1990 and 2021, highlighting the role of climate change. It noted that incidents of brain strokes, and deaths caused by it, as a proportion of the population had reduced significantly between 1990 and 2021. This trend was visible in India as well with deaths from subarachnoid haemorrhage declining by 34%, those from intracerebral haemorrhage coming down by 29%, and from ischaemic strokes reducing by 13% in this period.

The absolute number of brain stroke cases, however, was increasing. The study found that 84% of brain strokes in 2021 could be linked to 23 ‘modifiable’ risk factors, meaning these risks could be reduced or eliminated. These risks included environmental factors like air pollution, behavioural factors like smoking or diet choices, and metabolic factors like body mass index (BMI), blood pressure, kidney function or cholesterol.