We recommend that the PBS Commissioner for GSA-owned facilities: a. Conduct an accurate and complete assessment of HVAC systems to identify deficiencies in air filtration. Based upon the assessment, PBS should maximize central air filtration in existing HVAC systems without significantly reducing design airflow; b. Review and update current and future operations and maintenance contracts to ensure that they clearly identify the required MERV air filters and preventive maintenance schedules; c. Establish controls to ensure that PBS obtains and maintains complete preventive maintenance records; and d. Ensure that contracting officer representatives conduct inspections of mechanical rooms and preventive maintenance records to ensure that air filters meet MERV requirements.