Ambient noise is associated with an increased risk of stroke

Larisa Ines Yankoty

Credit: Photo courtesy

Every 10 decibel A (dBA) increase in outdoor noise is associated with a six percent increased risk of stroke in people ages 45 and older living in the Montreal area.

This is highlighted by a study published in the journal a few months ago Noise & Health. The longitudinal study was conducted by PhD student Larisa Inès Yankoty under the supervision of Professor Audrey Smargiassi from the University of Montreal’s School of Public Health.

This conclusion comes from coupling medical-administrative data from a cohort of nearly 1.1 million Montreal residents from 2000 to 2014 with noise sampling measurements recorded during that period by approximately 200 sound level meters installed throughout the area. The noise data obtained by Professor Smargiassi’s team are now being disseminated by the Canadian research consortium CANUE.

“Several studies, particularly in Europe, have already shown that noise has adverse effects on cardiovascular health, with some linking noise pollution to cases of myocardial infarction,” says Larisa Inès Yankoty.

According to the doctoral student, the present study is one of the few that establishes a link between noise and stroke frequency.

A stronger association for ischemic stroke

Audrey Smargiassi

Audrey Smargiassi

Photo credit: University of Montreal

During the period analyzed by Larisa Inès Yankoty, more than 25,000 people were hospitalized for stroke in the Montreal region, representing 2.5% of the cohort of people aged 45 and over.

The data show that ischemic strokes are more strongly associated with noise than hemorrhagic strokes. Ischemic strokes occur when a blood clot blocks a blood vessel in the brain, while hemorrhagic strokes occur when an artery in the skull ruptures.

On the island of Montreal, environmental noise is highest near major roads; The risk of stroke would therefore be potentially greater in people living close to these lines of communication.

“It is important to note that we are talking about an association between noise and the risk of ischemic stroke and not a cause-and-effect relationship,” emphasizes Audrey Smargiassi. Our statistical analyzes are flawed and do not allow us to state that the occurrence of a stroke is specifically due to ambient noise.

This study complements an international report from the Health Effects Institute, published in June, which reviewed 353 scientific articles published between 1980 and 2019 addressing the health effects of road traffic pollution. Audrey Smargiassi is one of the report’s signatories.

Which sounds correspond to decibels?

Sound intensity is expressed in decibels A on a scale from 0 dBA, the human hearing threshold, to around 120 dBA, the upper limit of normal noise in our environment.

Photo credit: Brutparif

Studies show that from 40 dBA at night and 55 dBA during the day, the effects of noise can manifest themselves in fatigue, stress, sleep or mood disorders and cardiovascular problems.

Chronic noise exposure between 85 and 105 dBA carries a long-term risk of hearing loss. At 105 dBA and above, there is an imminent risk of tinnitus – or even deafness.

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