Nanoparticles—long thought to be potentially hazardous to human health—have in reality been forming naturally for as long as humans have used silver, copper, and other metals for tools and jewelry. Using high-powered transmission electron microscopes and a new approach that allows for the direct observation of microscopic changes in nanoparticles over time, researchers found that silver nanoparticles deposited on the surface of SMART Grids slides began to transform in size, shape, and particle populations within a few hours, especially when exposed to humid air, water, and light.
