Far-UVC radiation is highly effective at inactivating microorganisms while exhibiting minimal penetration into human skin and eyes. This reduced tissue interaction lowers the risk of damage, allowing higher exposure limits and enabling safe disinfection of occupied spaces. However, there is no standard technique to quantify far-UVC inactivation rates of airborne microorganisms across a range of conditions and distances. This results in limited engineering solutions that would maximize inactivation. To address this, the University of Bristol has recently developed the QELEBS-UV (Quadrupole Electrodynamic Levitation and Extraction of Bioaerosol onto a Substrate). Microbe laden aerosol are levitated within an electrodynamic trap under controlled environment conditions (relative humidity, gas phase composition). The aerosol are irradiated with Far-UVC from a 222 nm KrCl excimer lamp for a set time, and after irradiation treatment, extracted from the trap for downstream viability analysis. Here, we describe the far-UVC inactivation of Group A Streptococcus pyogenes (GAS) and Influenza A (PR8) in respiratory fluid surrogates. Specifically, the effect of far-UVC in relation to particle composition, particle size (10 to 5 microns) and relative humidity (20% to 90%). A unique aspect of this study is the initiation of far-UVC exposure at different stages of the aerosol lifetime and a comparison with non-irradiated samples, enabling investigation of how aerosol aging influences far-UVC disinfection efficacy. These results identify the effects induced by far-UVC on pathogen-laden single particles and will establish how far-UVC installations need to be designed to effectively suppress airborne transmission and promote indoor air quality of the built environment.