Particle Formation and Growth in an Office under Far-UV Germicidal Ultraviolet Lights with Cooking, Cleaning, and Personal Care Products

Abstract Far-UV (222 nm) germicidal ultraviolet radiation (GUV222) is a promising indoor disinfection technology for pathogen control in occupied spaces. However, GUV222 generates ozone, which may react with volatile organic compounds and form secondary pollutants. We examined GUV222 effects on indoor aerosol formation during surface cleaning, personal care product use, and cooking in a real office environment. Experiments were conducted under Control, GUV222, and O3 addition conditions. The O3 addition experiments produced time-averaged O3 concentrations comparable to those observed during GUV222 operation, allowing comparison of aerosol responses under similar measured O3 levels. Cleaning products containing quaternary ammonium compounds (QAC) and some personal care products induced new particle formation (NPF) and growth. Selected QAC-containing products exhibited more persistent particle growth (64 nm hr–1) and larger final particle sizes under GUV222 than under O3 addition alone (43 nm hr–1), suggesting photochemical processes beyond ozone chemistry. Van Krevelen analysis indicated progressive oxidation of the organic aerosol during both GUV222- and O3-induced particle growth. In contrast, air-fryer cooking produced strong particle emission and growth under all conditions, with increases in nucleation-mode particles during both preheating and post-food-loading stages. Cooking itself is such a dominant particle source that it outweighs any incremental effect of GUV222 on particle populations. Fan operation substantially reduced QAC-driven NPF and growth. The indoor use of GUV222 should consider trade-offs between pathogen control and activity-dependent chemical reactivity and aerosol exposure, although reducing simultaneous use of QAC-based cleaners and enhanced ventilation and air circulation are useful mitigation strategies.