Ambient Ozone Exposure and Pneumothorax Risk After CT-Guided Lung Biopsy

Background/Objectives: To evaluate whether day-of-procedure ambient ozone exposure is associated with pneumothorax after CT-guided lung biopsy. Methods: This retrospective single-centre study included 160 CT-guided lung biopsies performed between January 2018 and February 2026. Environmental data from the day of biopsy were assigned from the nearest national monitoring station. The primary outcome was any pneumothorax on post-biopsy CT; the secondary outcome was drainage-requiring pneumothorax. Multivariable logistic regression included ozone exposure, emphysema, and access route through dependent lung area (ARDA). Ozone was analysed as a continuous variable per 10 μg/m3 and, exploratorily, using a ROC-derived threshold of ≥75.8 μg/m3. Restricted cubic splines assessed nonlinearity. Sensitivity models adjusted for needle size, biopsy system, operator identity, and season. Drainage-requiring pneumothorax was analysed using Firth logistic regression. Results: Pneumothorax occurred after 86 of 160 biopsies (53.8%), and 13 biopsies (8.1%) required drainage. Ozone was not associated with pneumothorax when modelled linearly (OR, 1.09 per 10 μg/m3; 95% CI, 0.97–1.23; p = 0.167). In exploratory threshold modelling, ozone ≥ 75.8 μg/m3 was associated with pneumothorax (OR, 2.76; 95% CI, 1.39–5.61; p = 0.004). Emphysema increased pneumothorax odds (OR, 2.16; 95% CI, 1.03–4.68; p = 0.047), whereas ARDA was protective (OR, 0.23; 95% CI, 0.11–0.45; p < 0.001). Spline analysis supported nonlinearity (p = 0.001). For drainage-requiring pneumothorax, only emphysema was significant. Conclusions: Ambient ozone showed an exploratory nonlinear association with pneumothorax after CT-guided lung biopsy, with a threshold signal around 70–80 μg/m3. ARDA was protective, whereas emphysema was associated with drainage-requiring pneumothorax.