Air pollution contributes to higher stroke risk, but socio-cultural factors remain important
Air pollution is an important factor in determining the risk of stroke, but concomitant factors should not be underestimated. At the Meeting of the European Neurological Society (ENS) in Prague, researchers from Hungary reported on a comparison of stroke frequency in two districts of Budapest showing that socio-cultural factors also significantly influence the risk of stroke.
“Previous international studies suggest that air pollution increases the risk of acute cardiovascular diseases, particularly heart attacks and ischemic stroke. Our data show that air pollution is not the sole predictor of these diseases,” Dr András Folyovich reported at the 22nd Meeting of the European Neurological Society in Prague. With his team from Szent János Hospital in Budapest, the neurologist examined 345 patients, from two districts of his city, who had suffered acute strokes in 2007.
With the help of a questionnaire, case histories were compiled covering possible risk factors, treatment, treatment adherence and health status three years after the stroke. The data was then compared with the air quality of their residential environments.
Working-class compared to upscale neighbourhoods
The patients came from two districts of the Hungarian capital that hardly could have been more different. The eighth district, Józefváros, has 84,000 inhabitants in an area covering 6.85 sq. km. It has one of the city’s highest population densities, yet only a small portion of its greenbelt. The average earnings and standard of living in this historic district is rather low. Józefváros patients were compared with others from the suburban twelfth district, Hegyvidék (the highlands), that has a population density six times lower, with only 56,000 residents per 26.67 square-km. The latter also enjoys significantly higher income, per capita living space and density of physicians care.
Air quality determined by volume of traffic
The researchers paid particular attention to the traffic conditions and air quality of both districts. While the eighth district is situated far from the city’s main thoroughfares, Budapest’s busy beltway crosses the eastern part of the wealthier twelfth district. Air quality measurements from three meteorological stations in the two districts show commensurate results: the worst air – measured by particulate matter, nitrogen oxide and -dioxide, sulphur dioxide and ozone – can be found in the area with heavy traffic in the twelfth district. But the outer zone of that same district also has the cleanest air, while the eighth district ranks in midfield.
Strokes occur in the eighth district of Budapest at a much earlier age than in the twelfth. The researchers had already determined in preliminary studies that the same holds true for deaths from stroke. The air quality, therefore, is not solely responsible for the risk of stroke. “Air pollution indeed contributes to stroke risk, but socio-cultural factors play an equally important role and must not be ignored,” concluded Dr Folyovich.
ENS Abstract P 619: Stroke – morbidity, mortality and air pollution. Follow-up of patients of the “districts VIII-XII of Budapest” Project in two districts of the Hungarian capital.