Insee Analyses · November 2024 · n° 99

In urban areas, lower-income households are generally more exposed to heat islands

Heat waves result in significantly higher temperatures in urban areas than in the surrounding countryside. Within cities, the heat island phenomenon affects neighbourhoods differently, depending on the density and quality of buildings, vegetation and levels of human activity. In Paris, Bordeaux, Lille and Nantes, it is both the most affluent and the most modest households that are most exposed, because they live in the city centres. In Lyon, Marseille, Montpellier, Nice and Strasbourg, lower-income households are the most exposed to the urban heat island phenomenon, while affluent households are the least exposed, as they live in less dense, greener, recently built suburban neighbourhoods. In general, poor households with at least one particularly young or elderly person are exposed to slightly higher average temperatures than other households. These households are more vulnerable to high temperatures, and have fewer options for coping with them: in particular, they are less likely to have air conditioning or a second home.