We have all seen the wide range of new products claiming to be effective against pathogens of all sorts. Common claims range from the rather ambiguous “Fights Germs”, to the more specific but questionable claim, “can disinfect up to 40 square meters of the surface at a time”. LightLab International Allentown, LLC’s CTO, Mike Grather recently wrote an article for the Illuminating Engineering Society’s FIRES forum discussing the measurement of GUV products (Click here for full article). In the article, Mike discusses the laboratory measurement of GUV products as well as the methods of predicting their performance in the field and ultimately verifying their performance with field measurements. This is all presented in the context of evaluating whether an installation is likely to expose inhabitants to harmful levels of irradiance, but also advocates for accurate measurements to evaluate if the device is capable of accomplishing its purpose of inactivating pathogens.