In addition to improved ventilation and filtration, Harvard's School of Public Health has also recommended that school's consider advanced air quality techniques; such as the use of ultraviolet germicidal irradiation (UVGI). UVGI uses low-wavelength UV-C light to disinfect surfaces and the air, and has been shown to be effective in destroying viruses such as influenza. As these systems require great care in implementation, the Harvard School of Public Health advises schools considering UVGI to consult outside technical experts.