Indoor Air Quality in Office Buildings: What to Measure and Fix

Four measurements that explain most complaints

• CO2 as a proxy for outside-air delivery — sustained readings above roughly 1,000 ppm point to under-ventilation.
• Relative humidity — Atlanta buildings should hold 40–60%; above that, microbial growth follows.
• Particulate (PM2.5) at the grille versus outdoors, which exposes filtration bypass and dirty ductwork.
• Temperature spread between zones, which usually reveals damper and airflow problems rather than thermostat problems.

Fixes that actually move the numbers

Cleaning coils and restoring airflow usually beats upgrading filters, because a high-MERV filter on a starved system just makes bypass worse. Seal filter racks and access panels, clean the air handler and duct interiors, verify outside-air dampers modulate, and only then raise filtration.

Where microbial growth is confirmed, remediation and UV-C at the coil are appropriate; where it is not, they are an expensive placebo.

Turning it into a program

Baseline the building, fix the mechanical causes, then re-measure and put the readings on a quarterly cadence tied to your filter and PM contract. That record is what defends the building when a tenant escalates.