France sees DIY chalk‑paint surge as heatwave drives home cooling efforts

Intense heatwaves across France have spurred a mass purchase of powdered chalk, with residents mixing the material with water to create a white coating for windows in homes and schools. The homemade “chalk paint” is intended to reflect solar radiation, lowering indoor temperatures.

French officials caution that the practice is only a temporary measure, emphasizing that it cannot replace proper roof and wall insulation. Health authorities also warn of potential respiratory hazards from inhaling chalk dust. Studies from Purdue University confirm calcium carbonate’s high reflectivity, and some reports link widespread reflective coatings to reduced urban heat‑related mortality, while noting the need for safer, longer‑term cooling solutions.