Background Blood eosinophil (EOS) has been considered as important biomarker in the management of airway diseases, but its distribution and determinants in the Chinese general population are unclear.

Methods We conducted a population-based study to identify blood EOS count and its determinants in a Chinese cohort. General citizens of Sichuan province in China were extracted from the China Pulmonary Health study. Data on demographics, personal and family history, lifestyle, spirometry and blood test were analyzed. A stepwise binary logistic regression analysis was performed to identify determinants of high blood EOS (>75th percentile).

Results 3310 participants were included, with a mean age of 47.0 years. In total population, the median blood EOS count was 110.0 (IQR 67.2-192.9) cells/?L, lower than smokers (133.4 cells/?L, IQR 79.3-228.4) and patients with COPD (141.5 cells/?L, IQR 82.6-230.1). Multivariate analyses revealed that smoking ?20 pack-years (OR 2.17, 95% CI 1.39-3.38), raising dog/cat (number =1, OR 1.60, 95% CI 1.10-2.34; number ?2, OR 1.72, 95% CI 1.18-2.52) and occupational exposure to dust, allergen or harmful gas (OR 1.63, 95% CI 1.20-2.22) were significantly associated with high blood EOS.

Conclusion This study firstly identified a median blood EOS count of 110.0 cells/?L and determinants of high blood EOS in a Chinese general population, including smoking ?20 pack-years, raising dog/cat and occupational exposure.