Indoor Carbon Dioxide (CO 2 ) concentrations and its impacts on health and wellbeing of the occupants is a widely discussed topic in building science. Although there is an abundance of knowledge on relationships between the Sick Building Syndrome (SBS) of office environments and naturally ventilated buildings, there is yet a limited knowledge available on associations’ of SBS in the students of higher educational facilities especially in air-conditioned lecture halls. To fill this research gap, present study has analyzed indoor CO 2 levels of 5 air-conditioned lecture halls with varying occupant densities for ongoing lectures of 2 hours. Statistically significant (α<0.05) strong positive correlation (R= 0.856) was shown between the occupant density and the CO 2 levels of the selected lecture halls. The results from the ordinal logistic regression shows significant odds ratios (OR>1, at 95% confidence interval) for the prevalence of symptoms such as headache, difficulties in concentration, dry throat, cough and tiredness/lethargy for certain lecture halls with high occupant densities. The results of the present study highlight the importance of adhering to proper design standards of lecture halls, optimum occupant control and selection of efficient air conditioning systems to maintain the health and wellbeing of higher education students.