Globally, more than 2 billion people lack access to clean drinking water, and water-borne illness accounts for 1.2 million deaths annually. Researchers are working to widen access to drinking water by developing effective and affordable filtration systems. Folia Materials, a Boston-based small business, has developed a water filter using green chemistry and paper that costs only $0.20. The resulting filter kills 99.9999% of bacteria and 99.7% of viruses, and removes 99.99% of protozoa and 99.8% of iron.