Indoor air quality (IAQ) measurements were conducted in three different towns (i.e. Centre, Lapseki, and Can) in Canakkale, Turkey (n = 121) throughout the year. All indoor environments were selected randomly among the volunteer participants of a previous health survey. Particulate matter (PM), Total Volatile Organic Compounds (TVOCs), Total Bacteria Concentration (TBC), Total Mold Concentration (TMC), and Carbon dioxide (CO2) together with temperature and relative humidity (RH) were measured monthly. Together with IAQ measurements, bronchial hyper-responsiveness indicators such as forced vital capacity (FVC) and forced expiration volume (FEV1) of the occupants of the homes were measured by monthly Pulmonary Function (PF) test. Furthermore, a comprehensive survey was given to the participants. The measured IAQ parameters showed seasonal and spatial variations (p < 0.05). Among them, the highest levels of TVOC, CO2, and PM were found in the winter, while the highest levels of both TBC and TMC were found in the summer. In general, levels of IAQ parameters and asthma prevalence were the highest in Can (i.e. industrial area). Also, IAQ adversely influenced the respiratory health of participants in Can (p < 0.05). Shortness of breath was the most prominent respiratory symptom. Negative associations between asthma and FEV1/FVC ratio, and between respiratory symptom score (RSS) and FEV1/FVC, support the idea that the PF test can be a good indicator for (early) prognosis of respiratory diseases. (C) 2015 Elsevier Ltd. All rights reserved.