Photochromic indicator and a method of documenting decontamination of an object using a photochromic indicator

A method of evaluating progress of a decontamination process, the method comprising:

• applying a photochromic indicator to a surface to be rendered pathogen reduced during the decontamination process, the photochromic indicator comprising a photochromic material that exhibits a visible response to being exposed to at least a predetermined dose of UVC light and, after the photochromic material ceases to be exposed to the UVC light, an appearance of the photochromic material returns to an original appearance that was visible before exposure of the photochromic material to the UVC light;
• applying a second material that exhibits a visible response to being exposed to light having a wavelength outside of a range of wavelengths constituting UVC light adjacent to the photochromic indicator;
• exposing the photochromic material to the UVC light impinging on the surface during the decontamination process for a length of time expected to be suitable for achieving pathogen reduction of the surface to a desired extent during the decontamination process;
• and
• after expiration of the length of time, using a light source that emits the light with the wavelength outside of the range of wavelengths constituting UVC light to cause the second material to exhibit the visible response, and determining an extent to which the decontamination process was completed based on whether the photochromic material exhibits the visible response.