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Cities are heating up and the poorest are on the front line: working-class neighborhoods, generally dense and sparsely vegetated, are on average the most exposed to the phenomenon of heat islands, INSEE revealed in a study on Wednesday.
Of the nine French metropolises, analyzed in detail using European satellite data, it is in Lyon that the difference in exposure to heat islands between households classified according to their standard of living is the most marked: in the summer of 2017, without a heatwave, it reached 0.41°C between the tenth of the wealthiest households and that of the least wealthy, ahead of Nice, where this gap rose to 0.37°C.
These differencesare not necessarily significant in terms of public health but serve as an indicator for greater deviations during future heat waves“, explains the institute, which mentions more pronounced differences in the city than in the countryside, especially when absolute temperatures are higher.
The urban heat island effect, linked to concrete which stores heat during the day and rebroadcasts it at night, but also to automobile traffic and the release of hot air from air conditioning systems, can be tempered by spaces vegetated and non-waterproofed soils, which retain humidity.
But not everyone is on an equal footing when it comes to this risk.
“Generally speaking, poor households with at least one particularly young or elderly person are exposed to slightly higher temperatures on average than other households. These households are more vulnerable to high temperatures, and have fewer options to cope with them: in particular, they more rarely have air conditioning or a second home.“, assures the institute.
In 2023, 55% of French people reported having suffered from heat in their home for at least 24 hours, a quarter suffered from it “frequently” during the summer, while the number of people living in homes “too hot” has increased by 26% since 2013, the Abbé Pierre Foundation disclosed in a report in August.
The government launched the “Resilient Neighborhoods” scheme at the end of 2022, with 250 million euros, to help 49 neighborhoods adapt to climate change by, for example, combating heat islands.
The City of Paris, which presented its fourth “climate plan” on Tuesday, plans to create an “island of freshness” less than seven minutes on foot from each resident.