University of Otago (Wellington) medical researcher and World Stroke Organization board of directors member Prof Anna Ranta’s latest research shows an association between stroke and climate change.
She said extreme temperatures, temperature variability, humidity, barometric pressure, wildfires, dust and sandstorms all increased the risk of having a stroke and of patients dying from stroke.
‘‘Temperature extremes and rapid swings in temperature, humidity and air pressure have a physiological effect on the human body.
‘‘Hot temperatures can cause dehydration, ‘thickening’ the blood and raising the risk of blocked blood vessels; while humidity and air pressure changes can increase blood pressure, an important cause of stroke.
‘‘Absolute changes in temperature and variations in temperature, barometric pressure and humidity — patterns that are intensifying as a result of climate change — all have an impact on stroke risk.’’
Prof Ranta said compound weather events — such as when extreme heat and drought come together, or when cold, humidity and wind come together — had an additive effect, increasing the risk of stroke and mortality even further.
‘‘Air pollution is another big factor in increasing the risk of stroke, with more than 20% of strokes globally attributed to air pollution.
‘‘While transport and industrial emissions are primarily a cause, rather than an effect of climate change, increases in frequency and severity of wildfires, sand and dust storms have been directly linked to climate change.
‘‘The particulate matter of the ‘air pollutants’ enter the bloodstream via the lungs, and cause damage to blood vessel walls.
‘‘This can result in blocked and ruptured brain arteries and cause a stroke.’’
She said older adults, workers frequently exposed to the weather and those in low and middle-income countries were at higher risk of stroke from environmental factors.
In response to the research, the World Stroke Organization (WSO) published a warning in the International Journal of Stroke that climate change posed an escalating threat to brain health.
The WSO said it was vital the world advance its efforts to reduce greenhouse gas emissions, to reduce the environmental drivers of stroke.
Its key recommendations included stepping up efforts to cut carbon emissions by promoting clean energy, plant-rich diets and active transport and educating patients about weather-related impacts on health.
