Why is it recommended to install UVGI lights downstream of filters?

Installing UVGI (Ultraviolet Germicidal Irradiation) lights downstream of filters is primarily recommended because UV light can destroy certain types of filter media if the light is introduced upstream. Many filter media, especially those made from organic materials or certain plastics, can degrade or be damaged by the exposure to UV light over time. Therefore, positioning the UVGI downstream allows the filters to effectively trap particles and impurities before the air is exposed to UV light, thereby preserving the integrity and performance of the filter media.

This consideration is crucial for maintaining the lifespan and efficiency of air filtration systems, ensuring that they function optimally without the risk of damage from the UVGI system. Other options, such as enhancing filter performance or increasing humidity levels, do not directly relate to the primary concern of protecting the filter material from UV damage. Clean air for UV effectiveness is also a valid point, but it is secondary to the need to avoid compromising the filter itself.