In this case report, a 40-year-old male patient with a persistent and productive cough lasting over 2 weeks, accompanied by dyspnea, who received an anti-tuberculosis drug regimen for 12 months without any clinical improvement at a different hospital before being referred to Persahabatan Central General Hospital was presented. In-depth clinical, and radiological investigations, the periodic acid-Schiff (PAS)-positive related to pulmonary alveolar proteinosis (PAP) confirmed through transbronchial biopsy (TBB). PAP is a rare lung disease with exceptionally low prevalence and incidence, Notably, the patient’s occupational environment played a crucial role in the diagnosis, as we identified occupational PAP secondary to chronic inhalation of ethylene oxide in a poorly ventilated work setting and inadequate respiratory protection. The patient was administered inhaled filgrastim (1 vial) at four intervals over 30 days, yielding favorable and satisfactory clinical as well as radiological outcomes. © 2024, Duzce University Medical School. All rights reserved.