Abstract- The objective of this work was to determine the microbiological quality of the air in the area of influence of the solid waste treatment plant of Cajamarca in the month of September 2 018 and in the month of March 2 019; in order to demonstrate whether there is microbiological contamination. We obtained a general average of 2 408 UFC⁄m³ as a result of the monitoring in September 2 018 and a general average of 1 472 UFC⁄m³ in March 2 019. obtained. According to the values obtained only in the month of September, it exceeds the quality standard proposed by the Occupational Safety and Health Administration (OSHA, 2,001), which establishes a limit of 2,000 UFU / m³.