Incandescent light bulb granted a Hungarian patent (No. 34541) for a tungsten filament lamp that lasted longer and gave brighter light than the carbon filament. Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1904. This type is often called Tungsram-bulbs in many European countries. Filling a bulb with an inert gas such as argon or nitrogen slows down the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater efficacy with less reduction in filament life. In 1906, William D. Coolidge developed a method of making "ductile tungsten" from
Phase-out of incandescent light bulbs significant health risks to adults, including pregnant women, or to children. If all electricity was generated by a coal power plant (which produce about half the electricity the U.S. consumes) and fluorescent light bulbs were all recycled with no mercury being lost, nearly 75% less mercury could be released in power plant emissions if incandescent bulbs were replaced by fluorescents, and with significantly less total mercury release even if no recycling occurred. However, a concern is that broken bulbs will introduce the mercury directly into a populated indoor area. Though more recent analysis indicates that the concerns about mercury release