Health. Green spaces, protection against strokes

In France, each year, according to the Ministry of Health and Solidarity, more than 140,000 people are victims of a stroke. Among women, who live longer, stroke is even the leading cause of death, ahead of breast cancer.

Air pollution and noise

But what is the relationship between the occurrence of this pathology and the environment? Is there a link between strokes and the presence of a greener environment near the home? This is what Spanish researchers wanted to know. A few years ago, this team from the Hospital del Mar, in Barcelona, ​​had already provided evidence of the existence of a relationship between atmospheric and sound aggressions and the risk of suffering a stroke. All of these factors, air pollution and noise, act as stroke triggers according to researchers. This time, they wanted to go further and compare epidemiological data with the presence of green spaces. Their results were published in early March in the journal “Environment International” (1).

The impact of particle levels

The study took into account information on exposure to three pollutants in more than 3.5 million people selected from the 7.5 million inhabitants of Catalonia over the age of 18, who had not undergone of stroke before the start of the study (in 2017).

More specifically, the team analyzed the impact of the levels of particles linked to automobile traffic: particles of less than 2.5 microns, nitrogen dioxide (NO2) and soot particles. They linked this level to the place of residence of each of the people studied. The number and density of green spaces within a radius of 300 meters around their homes were also studied.

Nitrogen dioxide is caused by road traffic

The results indicate several things, starting with a direct relationship between increased levels of NO2 in the atmosphere and the risk of ischemic stroke. “Thus, for each increase of 10 micrograms (µg/m3), this risk increases by 4%. Ditto with the two other types of particles studied, the risk increases. These numbers are the same for the entire population, regardless of other socioeconomic factors, age, or smoking habits,” the scientists explain in the study. Nitrogen dioxide is mainly caused by road traffic.

Reduced stress, increased physical activity

Therefore, the researchers’ conclusions are clear: “If we really want to reduce the multiple risks that this pollutant poses to people’s health, we must put in place bold measures to reduce car use in the city. »

A second discovery is the impact of the proximity of green spaces around the habitat. “Our study shows that people who are surrounded by higher levels of greenery in their place of residence reduce their risk of having a stroke by 16%”, continue the scientists. Exposure to green spaces is generally considered to have beneficial effects through a variety of mechanisms, such as reduced stress, increased physical activity and social contact, and even exposure to a microbial ecosystem enriched! The third lesson is more militant.

“We must achieve more sustainable towns and cities”

The study showed the existence of risks from particle concentration levels lower, on average, than those set by the European authorities, which are nevertheless considered safe! “Despite compliance with the levels set by the European Union, we are faced with the paradox that there is still a health risk. There is a direct relationship between exposure to pollutants in our environment and the risk of suffering a stroke”, explains the study, with this sentence as a conclusion: “We must strive to achieve cities and towns more sustainable places to live does not mean increasing your risk of disease! »

(1) “Air pollution and surrounding greenery in relation to ischemic stroke: a population-based cohort study”, published in “International Environment”, March 2022.

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