Background: Surgical fires are a preventable yet serious risk. In ENT, the fire triad is frequently assembled during procedures under local anaesthetic (LA), particularly when electrocautery or diathermy is used near oxygen delivery systems. The risk escalates when ambient oxygen concentration exceeds 30%. With increasing numbers of otological procedures performed under LA, due to aging patient populations and improved surgical techniques, understanding oxygen distribution in the surgical field is critical for fire prevention. Aim: This study aims to quantify oxygen concentrations at multiple sites within the surgical field during otological procedures performed under LA with tubeless airway support, thereby enhancing awareness among surgical teams about oxygen exposure and enabling preventive strategies. Methods: Ethics approval was obtained by the WSLHD HREC (ETH02088). Retrospective data was analysed from consecutive patients who underwent otological procedures under LA with Thrive anaesthesia performed by a single otologist at Westmead and Westmead Private Hospitals. Oxygen concentrations were measured using the ventilator's oxygen analyser at five key locations: operated ear, contralateral ear, oxygen delivery site, oral cavity, and under surgical drapes. The probability of oxygen concentration exceeding the critical 30% threshold was calculated. Results: 19 consecutive patients were eligible (3 cochlear implants, 1 tympanoplasty, 15 stapedecomies). Oxygen concentration at each subsite had a direct relationship with oxygen flow rate and delivery concentration. Oxygen concentration at the operated ear was more likely to exceed 30% when flow rates >50L/minute were used. Conclusion: This study addresses a critical knowledge gap by quantifying real-time oxygen exposure in ENT surgical fields. Findings can inform surgeons on the risk of airway fire during otological procedures performed under LA and help develop fire prevention protocols, enhancing patient safety.