Traffic under fire, even too much noise can increase the risk of stroke

Try to get health information related to over one million people living in the Montreal area. Then mix these data, relating to the period 2000-2014, with what is reported by the sound detectors (almost 200) located in the area. Calculate everything and you will find that in addition to cholesterol, hypertension, diabetes, overweight and the classic cardiovascular risk factors, exposure to environmental noise can also endanger cerebral circulation. And significantly: for every 10 decibel increase in ambient sound intensity, there is a 6% increased risk of stroke for people aged 45 and over. In particular, the association between noise pollution and brain injuries would be particularly significant for ischemic injuries and not for those of a haemorrhagic nature.

The association between noise and ischemia

The complex research leading to this conclusion was published in Noise & Health and was coordinated by Larisa Inès Yankoty and Audrey Smargiassi of the University of Montreal. 1.1 million subjects who live in Montreal were followed for about fifteen years, by crossing the data with those on sound measurements carried out by a network of sound level meters present throughout the city. Over 25,000 people were hospitalized for stroke on the island of Montreal during the observation period. As expected, ischemic strokes were more frequent, about five times more than hemorrhagic ones. And it is precisely for these injuries that the relationship with exposure to noise pollution clearly emerged, which is obviously greater in the areas surrounding busy roads. Let’s be clear: as experts recall, we are talking about an association between noise and the risk of ischemic stroke, not a cause-effect relationship. But the data are still of great interest.

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Thresholds at risk

According to several studies, a noise higher than 40 decibels at night and 55 during the day could induce asthenia, stress, sleep problems and obviously also put the cardiovascular system at risk. And unfortunately we are exposed to these risks: just think that exposure to noise exceeds 90 decibel for eight hours a day, basically a threshold that defines loud noise like the siren of a passing ambulance, can induce permanent hearing loss over the years. Moreover, as confirmed by the Canadian survey, if you live in a particularly noisy area, hearing pollution could also lead to alterations in blood circulation, increasing the dangers to the health of the heart and vessels.

More attention to the environment

It is not the first time that protracted noise pollution has been placed in the dock for a possible increased risk of cardiovascular disease. “This study shows once again how the environment can affect well-being by interacting with complex mechanisms such as blood coagulation and therefore the consequent cardiovascular risk – he comments. Ezio Ghigo, scientific coordinator of SaluTO-Turin Medicine and Wellness and lecturer at the University of Turin. Obviously it is necessary to continue with the studies, also because we are faced with an association and not a precise correlation: in short, the explanation of a precise cause-and-effect mechanism remains but the certainty remains that excessive noise in metropolises represents a risk factor. to consider “. In this sense, there are observations that excessive noise can, among other things, cause insomnia and sleepiness at night and promote obesity. And the effects on the neuro-vegetative and endocrine systems and on the sleep-wake rhythm are worrying, which see urban noise associated with arterial hypertension, cardiac ischemia and unfortunately also the risk of stroke.