The microbiological dynamics of ambient air need to be monitored to ensure indoor air quality and minimize health risks, since that excessive exposure to bioaerosols may be associated with the development of various respiratory and/or systemic diseases. Regarding about decontamination and sanitation of several places, conventional sterilizing processes are being used, and the most frequent is the use of chemical products. The use of hydrogen peroxide (H 2 O 2 ) as a decontaminant in indoor environments is already widely used as an antiseptic and is an effective antimicrobial agent because it has recognized biocidal action. Objective: This study aimed to characterize and evaluate the efficacy of hygienization by aerolized hydrogen peroxide against the presence of fungi and bacteria found in the indoor air of different environments with a large circulation of people from the city of São Paulo Methods: Five sample collection points were defined in the city of São Paulo; the air samples were collected before and after cleaning with aerolized hydrogen peroxide, using the Merck® MAS 100 NT air collector. One of the environments was analysed for 60 days to verify the effectiveness of maintaining the sanitation protocol with H 2 O 2 . The collected material was taken to the laboratory at the Adolfo Lutz Institute. Results: there were no large variations in the physical parameters during the application of H 2 O 2 , not even changes in the concentration of CO 2 and formaldehyde; aerolized H 2 O 2 showed biocidal action for both microorganisms in the first assessment after application in the studied environment (3 hours). That there was a significant reduction in the amount of CFU/ m 3 of microorganisms in the environment analysed for 60 days, with the greatest reduction in the first month, which was 61.5% (N=416) for fungi and 86.6% (N=1228) for bacteria. Conclusions: Hydrogen peroxide is a high-level disinfectant. Its already recognized biocidal action is related to the fact that this agent is an oxidizer. The maintenance of sanitization with H 2 O 2 aerolized aeration was shown to be necessary given the gradual reducing potential in the CFU/m 3 of microorganisms that this method indicated in the analysed environment for 60 days.