Associations between environmental exposure, lifestyle, and the risk of respiratory infections among 67890 adults: A population-based cohort analysis using UK Biobank data.

Background: Respiratory infections pose a major global health burden. While green spaces are generally thought to benefit respiratory health, research often overlooks the roles of private gardens and the interaction between environmental exposures and lifestyle behaviors. This study uses UK Biobank data to examine the integrated associations of environmental exposures, lifestyle habits, and respiratory infections. Methods: We conducted a large-scale cohort analysis based on UK Biobank data. Environmental exposures were assessed using geospatial data linked to residential addresses, including green space and domestic garden percentage (within 300 m and 1000 m buffers), natural environment accessibility, and coastal proximity. Cox proportional hazards regression models were used to estimate hazard ratios (HRs), adjusting for demographic characteristics (sex, age, BMI), socioeconomic status, and lifestyle behaviors (insomnia, smoking status, alcohol consumption, and physical activity). Results: A total of 46,288 healthy individuals and 21,602 patients with respiratory infection were included. Results revealed a scale-dependent "dual effect" of green space: higher greenspace percentage within a 300 m buffer was protective (HR=0.93, 95% CI: 0.88-0.99), whereas within a 1000 m buffer, it was associated with an increased risk (HR=1.10, 95% CI: 1.02-1.19). Domestic gardens and natural environments at 1000 m were generally protective. Greater distance to the coast was associated with a lower risk of most respiratory infections but a potentially higher risk of tuberculosis. Male gender, older age, higher BMI, smoking, and insomnia were risk factors, while physical activity and alcohol consumption were associated with lower risks. Conclusions: This study provides novel insights into the complex interplay between environmental exposures and lifestyle factors. The divergence between the protective effects of immediate greenness (300 m) and the risks associated with broader vegetation coverage (1000 m) suggests a trade-off between accessibility benefits and potential exposure to aeroallergens. Public health strategies should prioritize "low-allergen" urban planning and promote healthy lifestyles-particularly physical activity and smoking cessation-to mitigate respiratory infection risks.