This research was performed with the subject of 111 offices in a chemical plant of Korea. Airborneconcentration level of carbon dioxide, carbon monoxide, formaldehyde and total suspended particulates inthe office rooms were measured along with temperature and relative humidity. Simultaneously, generalcharacteristics and subjective health symptoms of 500 office workers were investigated through aquestionnaire consisting of the five point weighting method : 0 = not at all, 1 = a little bit, 2 = moderately,3 = quite a bit and 4 = extremely. Results showed that the mean values for temperature and relativehumidity in investigated office rooms were 22.2℃ and 34.3%, respectively. The concentrations offormaldehyde, PM10, carbon dioxide and carbon monoxide were 0.17 ppb, 28.8 ㎍/㎥, 0.95 ppm and 424 ppm,respectively. 56.4% of all the workers investigated replied with a sense of fatigue or weariness (mean=2.23),drowsiness or languidness (mean=2.22), sneezing (mean=2.11) and ophthalmia oreye fatigue (mean=2.07).Female workers, non-smokers, non-drinkers, workers who do shift more than nine hours a day, and workersin poor health experienced more subjective symptoms than other workers (p<0.05). Subjective symptoms ofoffice workers were significantly associated with the following items of office characteristics: the purchasedate of office equipment, the change of office furniture, the use of paint, smoking in the office, ventilationcondition, the use of an individual air-conditioner, the use of a fax machine, the degree of office repair, theproportion of workers per office, the degree of satisfaction in office environment, and the operation hoursof the air-conditioner. Also, subjective symptoms were positively correlated with indoor environmentalfactors such as relative humidity, carbon dioxide level, level of PM10, and formaldehyde (p<0.05). Inconclusion, office characteristics and air quality in a chemical plant affected subjective health symptoms ofoffice workers. Thus, in order to improve the health of workers, to enhance work efficiency, and to establisha better office environment, air quality control in office rooms by optimal ventilation, adequately occupiednumber of workers in one office, and maintenance of office equipment should be fulfilled thoroughly.keywords：Air quality, Subjective health symptom, Formaldehyde, PM10, Carbon monoxide, Carbon dioxide