Modernization has led to greater usage of Air Conditioners (ACs) in our daily lives. It is observed that the occupants of office buildings with ACs consistently report on average more symptoms than do occupants of office buildings with natural ventilation referred to as Sick Building Syndrome (SBS). The appearance of symptoms reduces work efficiency and increases absenteeism due to sickness (sickness absenteeism). Therefore, the present study was planned to evaluate the impact of usage of ACs on SBS and to find out the association of ACs with sickness absenteeism and lung function tests. This study was conducted on 200 healthy non-smoker adults in the age group of 18 to 45 years who were using ACs for at least 6 to 8 h/day for more than 2 years (group I). And 200 healthy adults, age and gender-matched, with the same work pattern, not using ACs at all served as controls (group II). The basic information on the usage of ACs and the prevalence of discomfort related to neural symptoms, respiratory symptoms, and skin and mucous membrane related to SBS was obtained through a questionnaire. The building-related symptoms in group I males were more compared to group II males and significantly higher in group I males compared to females. We observed that the appearance of symptoms of SBS led to sickness absenteeism among group I participants. Lung function tests especially FVC, FEV1, PEFR, and MVV were significantly reduced among group I males and females compared to group II males and females. ACs have a profound effect on the quality of the air we breathe and on human health than just lowering the temperature. There is a higher prevalence of SBS-Respiratory and allergic symptoms in AC users.