HomepageMedical Entrance Exam GkSeries Editor in Medical Entrance Exam Which of the following is a secondary pollutant? Which of the following is a secondary pollutant? Option 1 : CO Option 2 : CO2 Option 3 : O3 Option 4 : SO2 Next Read: Which one of the following flow regimes is more favorable for gas lift operation? ยป BiologyMedicalNEET GkSeries Editor: