Floating blocks of concrete combat dengue fever

Dengue fever, which causes high temperatures, vomiting, and joint pain, threatens more than 2.5 billion people globally. The disease is transmitted by mosquitoes and, like malaria, has proven difficult to eradicate. In order to combat mosquito larvae without the use of dangerous chemicals, researchers have developed floating blocks of aerated concrete that release oxidizing chemicals into the water when exposed to sunlight, Chemistry World reports. The oxidants can damage the larvae themselves, but can also destroy their food sources: bacteria, fungi, and plankton. The blocks are cheap, too, costing only 30 cents for about 800.