26 Sep 2023

Evaluation of a Visible Light Responsive Photocatalytic Coating to Resist Microbial Contamination and Increase Indoor Air Quality

Abstract: To meet new Department of Defense (DoD) energy standards, buildings are being constructed, and existing buildings are being retrofitted with tighter envelops. These new standards can reduce operational costs significantly but also limit fresh outdoor air coming into the built environments. This can result in the accumulation of harmful substances within buildings, which can have adverse effects on its occupants. New photocatalytic coatings may be a solution to this ever-increasing problem as they have the ability to destroy both chemical and biological toxins when activated with light. This work evaluated a novel indoor-light-reactive photocatalytic coating for its ability to eliminate or reduce microbial contamination under in situ test conditions. However, air and surface sampling revealed no reduction in either viable fungi and bacteria or total air-borne mold spores. Additionally, no significant differentiation could be made in the composition of volatile organics between the treated and untreated areas. However, testing the photocatalytic activity of the coating with standardized test methods and increased illumination, revealed the coating did exhibit antimicrobial activity against mold, bacteria, and viruses. This suggested that there may be limited benefit to using the indoor-light-reactive photocatalytic coating to inhibit microbial contamination unless specific lighting conditions can be met.

1 Oct 2020

Comparison of Antifungal Efficiencies of Photocatalytic and Antimicrobial-Infused Coatings: Evaluation of Five Antimicrobial Coatings Using Standard Test Methods

Abstract: New buildings are being constructed and existing buildings retrofitted to be more energy efficient to meet increasingly stringent Department of Defense (DoD) energy standards. Although these standards save energy and lower operational costs, they also limit fresh air within a structure and can cause a buildup of harmful substances in indoor environments. Of particular concern are molds, which can put building occupants at risk and damage infrastructure. One possible solution to this increasing Army problem is to coat building materials with photocatalytic paints, which have the ability to both destroy microorganisms as well as the toxic byproducts they produce. This work compared two next-generation photocatalytic coatings against three more traditional antimicrobial-infused coatings for their ability to resist fungal contamination using three accelerated test conditions. Under each test condition the photocatalytic coatings were found to perform poorly compared to the antimicrobial-infused coatings. Moreover, the control coating, which contained no active antimicrobial (standard latex paint), performed as well as or better than all the antimicrobial coatings tested. This suggested that there may be little benefit to using antimicrobial coatings to inhibit fungal colonization over a standard latex paint; however, further testing is required to confirm this perception.