Objective The aim of this study was to evaluate the quality of air in surgical centre rooms of a hospital in the South of Brazil. Methods An evaluation of the parameters of comfortability (temperature, luminosity, concentration of carbon dioxide and relative humidity), microbiological analysis and chromatographic of the particulate material present in the filters of air conditioners was carried out. Results Regarding the aspects of comfortability, three surgical rooms did not present temperature in accordance to the current legislation, but were found within the ideal patterns in other environmental factors. In the analysis of particulate material, a larger number of fungal bio-aerosols of viscous colonies was obtained than filamentous. Conclusion It was found that the main aspects related to the quality of air in the hospital being studied are being accomplished; however there is a need of modifying building aspects in the surgical rooms in order to reduce the possibility of contamination by air and decrease the concentration of carbon dioxide in the environment.