Living in a noisy area increases the risk of suffering a more serious stroke
The high levels of environmental noise we are subjected to in large cities can increase both the severity and the consequences of an ischaemic stroke. More precisely, researchers calculate the increased risk at 30% for people living in noisier areas. In contrast, living close to green areas brings this risk down by up to 25%. This is the first time that these factors have been analysed in relation to stroke severity. The study has been published in the journal Environmental Research.
The researchers looked at the influence of noise levels, air pollution (particularly suspended particles smaller than 2.5 microns; PM2.5), and exposure to green areas on nearly 3,000 ischaemic stroke patients treated at Hospital del Mar between 2005 and 2014. To do this, they used data from the Cartographic Institute of Catalonia, as well as models to analyse atmospheric pollutant levels, the noise map of Barcelona, and satellite images to define areas with vegetation. They also took into account the socioeconomic level of the locality where the patients lived.
The study gives us initial insight into how noise levels and exposure to green spaces influences the severity of ischaemic stroke. "We have observed a gradient: the more green spaces, the less serious the stroke. And the more noise, the more serious it is. This suggests that factors other than those traditionally associated with stroke may play an independent role in the condition”, researchers explain. Exposure to green spaces can benefit human health through various mechanisms. For example, it can reduce stress, encourage social interaction, and increase levels of physical activity.
Exposure to high levels of traffic noise increases the risk of suffering a more serious ischemic stroke by 30%
More noise, greater stroke severity
Previous studies have demonstrated that living in places with high levels of air pollution or noise, or with fewer green areas, exposes the population to a higher risk of suffering an ischaemic stroke. This work broadens our knowledge in this field, showing that the place where we live affects not only the risk of suffering a stroke, but also its severity if one occurs. In this sense, the results indicate that patients living in noisier areas presented more severe strokes on arrival at hospital. The researchers have analysed the effects of stroke on neurological deficits, such as speech impairment and mobility, using the NIHSS (National Institute of Health Stroke Scale).
The researchers did not aim to determine which noise levels lead to increased risk, but rather to detect a gradient by comparing patients living in noisier areas with those living in quieter areas. Indeed, the World Health Organisation (WHO) recommends traffic noise limits of a maximum of 53 decibels during the day and 45 decibels at night. "The average noise level to which patients have been exposed, as well as the general population of the study area, requires reflection, as it is considerably above the WHO recommendations", point out the researchers. The same researchers have already revealed that high levels of air pollution from diesel engines increase the risk of suffering atherothrombotic stroke by 20%.
Rosa Maria Vivanco-Hidalgo, Carla Avellaneda-Gómez, Payam Dadvand, Marta Cirach, Ángel Ois, Alejandra Gómez González, Ana Rodríguez-Campello, Pablo de Ceballos, Xavier Basagaña, Ana Zabalza, Elisa Cuadrado-Godia, Jordi Sunyer, Jaume Roquer, Gregory A. Wellenius. Association of residential air pollution, noise, and greenspace with initial ischemic stroke severity. Environ Res 2019; 179(Part A): 108725.