On days with the highest concentration of soot in the atmosphere, there is a 20% increase in the risk of suffering an atherothrombotic stroke, according to a study by IMIM, the Hospital del Mar and the Barcelona Institute for Global Health (ISGlobal). Researchers have found a direct relationship between this contaminant, originating from the poor combustion of diesel engines, and the increase in cases.
Strokes, or cerebrovascular accidents, are the leading cause of death among women and the third largest among men in Spain and it is calculated that 1 in every 6 people will be affected over the course of their lives. In Catalonia, every year 13,000 new cases and 3,800 deaths from this condition are recorded. Atherothrombotic stroke is the third most frequent type and is associated with high levels of cholesterol, smoking and diabetes. In general, some 90% of strokes are related with risk factors such as these.
The study has analysed data from nearly 3,000 patients seen at the Hospital del Mar for a stroke between the years 2005 and 2014, and it has been possible to confirm how the presence in the air that we breathe of this element, originating from poor combustion of diesel engines, acts in the short term as a trigger of a specific type of ictus, the atherothrombotic type, caused by the detachment of atheratomous plaques which are formed by cholesterol, calcium and other substances that accumulate in the arteries and cause occlusion in a blood vessel. The researchers wanted to highlight that this shows “that the harmful effects of environmental contaminants for people’s health goes beyond their impact on respiratory systems and cancer. We have shown that the increase in black carbon in the environment also affects the brain’s circulatory system and increases the risk of suffering a stroke”.
High pollution levels increase the risk of suffering an atherothrombotic stroke
A 20% increase in risk
In the case of black carbon, or soot, the analysis of data indicates a clear relationship between its levels in the air and the risk of suffering an atherothrombotic strike. Thus, for each increase of 1.7 µg/m3 (micrograms per cubic metre) of its concentration in the air, the risk of suffering a stroke during the following 24-72 hours grows by 20%. This is due to the fact that exposure to soot causes an increase in the inflammatory particles in our body: “a pro-thrombotic state”, the researchers explain. These are cases of “people who already suffer an underlying atherosclerotic disease process and in whom air pollution acts as a trigger, in other words, the pollution triggers a series of inflammatory reactions in the body that may end up causing the detachment of the atheratomous plaque which leads to the occlusion of a blood vessel and, therefore, the risk of suffering a stroke”.
In fact, according to data from Barcelona City Council, by reducing levels of pollutants in the air in the city to those recommended by the WHO, 659 premature deaths would be prevented each year.
Rosa Maria Vivanco-Hidalgo, Gregory A. Wellenius, Xavier Basagaña, Marta Cirach, Alejandra Gómez González, Pablo de Ceballos, Ana Zabalza, Jordi Jiménez-Conde, Carolina Soriano-Tárraga, Eva Giralt-Steinhauer, Andrés Alastuey, Xavier Querol, Jordi Sunyer, Jaume Roquer. Short-term exposure to traffic-related air pollution and ischemic stroke onset in Barcelona, Spain. Environ Res 2018; 162: 160-165.