Role of HRCT in detecting early lung changes in smog-exposed individuals with normal chest radiographs
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Date
2026
Journal Title
Journal ISSN
Volume Title
Publisher
UMT, Lahore
Abstract
Objective : To determine the frequency and pattern of HRCT parenchymal abnormalities in smog exposed patients with normal chest radiographs. To assess the association between duration of smog-exposure and severity of HRCT detected lung changes. Methodology : This cross-sectional observational study examined the frequency and pattern of High-Resolution Computed Tomography (HRCT) parenchymal abnormalities in smog exposed adults whose chest radiographs had been reported as normal, and assessed whether longer duration of smog exposure was associated with greater severity of CT-detected changes. Seventy adults residing in designated high-pollution urban zones of Lahore were enrolled from the Departments of Radiology at Itefaq Hospital and Capital Diagnostic Centre using consecutive purposive sampling. All participants had documented smog exposure of at least three years, at least one respiratory symptom, and a normal chest radiograph. Standardized non-contrast HRCT of the chest was performed and interpreted by two independent radiologists using a dual-reader protocol. Data were analyzed using SPSS version 26.0, with chi-square, Fisher exact, and Mann-Whitney tests were applied. Results : HRCT parenchymal abnormalities were detected in 57 of 70 participants (81.4%) despite normal chest radiographs. Ground-glass opacity was the most prevalent finding (50.0%), followed by air trapping (32.9%), bronchial wall thickening (24.3%), centrilobular nodularity (20.0%), and interstitial changes (15.7%). Ground-glass opacity was significantly more prevalent in Barki Road residents compared to all other residential zones (81.8% versus 44.1%; Fisher exact p = 0.045, OR = 5.71). Stratification by daily outdoor smog exposure duration revealed a statistically significant dose-dependent gradient, with HRCT abnormality rates increasing from 66.7% among those with less than 4 hours of daily exposure to 95.7% among those with more than 8 hours (p = 0.038). Conclusion : HRCT detected lung abnormalities in 81.4% of smog-exposed Lahore residents with normal chest X-rays, most commonly ground-glass opacity (50%). Findings were diffusely distributed, with higher prevalence in Barki Road residents. Results show that chest radiography underestimates smog-related lung injury, while HRCT identifies significant subclinical disease