There is a way to prevent deadly malaria at a low expense. It is to change the house. Medical researchers in Africa developed a win-win technology that lowers indoor temperatures and blocks mosquitoes that spread malaria by remodeling dwellings.
Bernard Abong'o and colleagues, entomologists at the Kenya Medical Research Institute, said on the 5th (local time) that they had "demonstrated the effectiveness of sustainable dwelling retrofits that can lower indoor temperatures and block mosquitoes in rural areas," in the journal Nature Medicine. Low-income households in Africa are reluctant to install screens because they raise indoor temperatures, but the low-cost cooling technology solved that problem.
◇ Screens once shunned for heat now possible as indoor temperatures drop
According to the World Health Organization (WHO), 610,000 people died of malaria in 2024. Most victims are children in underdeveloped African countries. Abong'o turned to dwelling modifications to prevent malaria infection.
Rural houses in Kenya, as Korea did in the past, use corrugated iron for roofs. Corrugated iron is a material made by galvanizing thin steel sheets to prevent corrosion. It is thin and easy to work with, so it is widely used in dwellings. But it absorbs heat well, so indoor temperatures do not drop even at night.
A hot interior invites malaria. People have no choice but to keep doors and windows open, exposing themselves to mosquitoes that transmit malaria. Installing screens on open doors would work, but many people avoid them because they block airflow and make interiors hotter.
The team tested three cooling strategies in a village in western Kenya. They added more windows to 10 households to improve ventilation. In another 10 households, they installed traditional plant-based mats on ceilings to keep roof heat from entering indoors. The remaining 10 households had white, heat-reflective paint applied to their roofs. The team installed screens on windows, doors and eaves in each home to block mosquito entry.
The experiment found that painting the roof white was the most effective strategy for lowering indoor temperatures. Compared with other homes, indoor temperatures were 3.3 C lower during the day and 2.4 C lower at night. At the same time, the screens reduced populations of female Anopheles funestus, which transmit malaria, by 77%. Culex mosquitoes, which spread Japanese encephalitis, fell by 58%.
With enough money, homes with air conditioning can be built in Africa, too. The problem is money. The team said the expense for the dwelling improvement work tested this time was $189 (about 280,000 won) per household. Abong'o said, "In rural Africa, the only ways to block mosquitoes were nets and insecticides," adding, "Dwelling retrofits are a sustainable, effective way to lower indoor temperatures and prevent mosquito entry."
In fact, 85% of the households participating in this experiment said they were willing to spend money on dwelling retrofits. The team said it plans to expand the retrofit experiment to 300 households with support from the Wellcome Trust, a U.K. nonprofit research funding foundation.
◇ White paint that lowers indoor temperatures by 13 degrees when applied
The cooling effect of white roofs has long been known. In hot places, houses are often painted white. White reflects all light, making it appear white. That makes it good at blocking heat. Steven Chu, who won the Nobel Prize in physics in 1997 and served as U.S. secretary of energy, argued that to curb warming, all roofs worldwide should be painted white.
Scientists are developing paints that realize perfect white to boost cooling performance. In 2021, a team led by Purdue University professor Xiulin Ruan reported in ACS Applied Materials & Interfaces that white paint significantly reduced indoor temperatures.
White paint currently on the market reflects only about 80% to 90% of sunlight. The Purdue team used barium sulfate, a substance that whitens drugs and cosmetics, and varied particle size to develop a paint that reflects 98.1% of sunlight. In outdoor tests, areas coated with the new white paint were 13.3 C cooler than their surroundings under strong midday sun and remained 7.2 C cooler at night.
The cooling effect of white paint comes from blocking light while emitting heat as infrared radiation. Heat expelled from air-conditioning condensers remains on Earth and causes urban heat islands. By contrast, the new paint emitted more than 95% of infrared radiation in a wavelength band that is not absorbed by the atmosphere and can escape directly into space.
In 2018, Columbia University's Yuan Yang reported in Science a white paint that reflects up to 99.6% of sunlight. Applied to buildings, it reflected nearly all wavelengths of sunlight and lowered surface temperatures by up to 6 C.
The team said air bubbles embedded in the paint make it whiter. Ice is transparent because light passes through, but when shaved into a granita, air enters and reflects light, making it look white—the same principle. The cooling paint's air bubbles reflect not only visible light but also ultraviolet and infrared, the team said.
References
Nature Medicine (2026), DOI: https://doi.org/10.1038/s41591-025-04104-9
ACS Applied Materials & Interfaces (2021), DOI: https://doi.org/10.1021/acsami.1c02368
Science (2018), DOI: https://doi.org/10.1126/science.aat9513