Methods and lighting systems to deactivating deactivate MRSA bacteria in a volumetric space over a period of time. At least one lighting element of each of one or more lighting fixtures provide light. The light includes a first disinfecting light having a wavelength of about 405 nm and a minimum integrated irradiance of 0.01 mW/cm2, and a second component having a wavelength of greater than 420 nm. The one or more lighting elements of the one or more lighting fixtures apply a determined total radiometric power to produce a desired power density measured at any exposed surface within the volumetric space during the period of time. The minimum power density includes a minimum integrated irradiance of the disinfecting light equal to 0.01 mW/cm2.
