Indoor air quality of 5 blocks in Alexandria was investigated. VOCs-enrichment factor [VEF], that is potentially useful in IAQ investigations was evaluated in this study. Concentrations of VOCs and CO₂ were determined for 26 units and VEF was calculated. 100 housewives were selected randomly for the study [20 from each block]. For each subject, an interview, general and systemic examination, pulmonary function tests, and radiological examination were carried out. The most frequent complaint among the study population was the nonspecific complaints [51%] followed by respiratory system complaints [34%], while 28% of the studied sample reported mental complaints. There have been many studies in residences, but few include both VOCs and CO₂ concentrations. Although VOCs concentrations vary over a large range of concentrations for indoor [0.150-2.989 mg/m³] and for outdoor [0.123-2.975 mg/m³], the presence of elevated VOCs indicates strong contaminating source in the building. Outdoor VOCs concentration can be quite variable reflecting vehicular, commercial, and industrial emissions. CO₂ is a crude indicator of ventilation efficiency. 65% of units had VEF of about 1 indicating that bioeffluent emissions prevail, 23% of units had VEF >5 which indicates existence of strong abiotic VOCs sources, and 12% of units had VEF < 0.3 which indicates existence of large combustion source of CO₂. Adverse health responses potentially caused by VOCs in nonindustrial indoor environment are irritant, systemic, and toxic effect. In addition, symptoms such as headache, fatigue, and mental confusion are indicators of the presence of combusion products such as CO₂. The VEF is applicable to residences and the present study suggests that people suspecting a connection between their health impairment and housing conditions should be taken seriously.