How to start a building air quality program
A building air quality program starts with three decisions made before anyone turns on a monitor: what to measure, where it goes, and what happens the first time a reading crosses a line. Skip any of them and a building ends up where most do now: testing the air only after a tenant complains, with no record to check the complaint against.
Picture a property manager hearing that the third floor feels thick by 2pm, with no way to know whether that is new this week or has been true all year. A building air quality program closes that gap. This post covers four steps that turn a one-time test into an ongoing program: what to measure, where monitors go, how long a baseline takes before you trust it, and how to budget the program per space instead of per building.
Key Takeaways
- A building air quality program covers five readings room by room: CO₂ in ppm, PM2.5 in µg/m³, VOCs, relative humidity in % and temperature in °F, each checked against the outdoor air.
- A good indoor CO₂ reading stays under roughly 1,000 to 1,100 ppm, the range ASHRAE's position on indoor carbon dioxide treats as a ventilation indicator, not a health limit.
- A good PM2.5 reading stays under 9.0 µg/m³ as a daily average, the top of the EPA's Good band for fine particles.
- A monitor belongs in every occupied room, not just the lobby, and a baseline needs four to six weeks to show a full occupancy cycle before it is reliable.
- OSHA has no general indoor air quality standard and does not require a program; the case for one is a tenant complaint answered with a number instead of a guess.
What a building air quality program should measure
A building air quality program needs five readings, not one: CO₂ in ppm (how stale a room gets), PM2.5 in µg/m³ (fine particles from smoke, traffic or a renovation), VOCs (off-gassing from new paint or furniture), relative humidity in % (the range that keeps surfaces from staying damp) and temperature in °F. Each one means more once it is checked against the air outside that same day.
Workplace air quality testing covers what each reading means and what to try when one of them moves. A program's job is deciding how continuously to collect all five, in which rooms, before the first complaint rather than after it.
Put a monitor in every occupied room, not just the lobby
A single monitor in the lobby only describes the lobby. A basement break room, a server closet with its own exhaust problems, and an open floor of cubicles upstairs can all read differently on the same afternoon, so a program sizes monitors per space, not per building.
That matters most in a multi-tenant building, where a complaint on one floor says nothing about the floor below it. One monitor per occupied space, kept running, is the only way to know which floor actually has the problem when a tenant calls.
Set a CO₂ baseline against the air outside
Outdoor air runs close to 420 ppm. ASHRAE's position on indoor carbon dioxide puts the practical indoor ceiling about 700 ppm above that, so a program treats roughly 1,000 to 1,100 ppm as the point where outdoor air ventilation has fallen behind occupancy, not a health limit on CO₂ itself (ASHRAE's position document). OSHA's own investigators use that same 1,000 ppm figure as their practical sign of inadequate ventilation, five times below OSHA's enforceable industrial limit (OSHA's Technical Manual).
Many buildings already run a demand controlled ventilation sequence that resets outdoor airflow once CO₂ crosses this same differential. A program's own reading, kept independent of that system, shows whether the reset is happening (demand controlled ventilation).
Decide the response before PM2.5 climbs
On a wildfire smoke day or during a renovation, PM2.5 is usually the number that moves first. The EPA's Good band for fine particles tops out at 9.0 µg/m³ as a daily average (EPA fact sheet). A program decides in advance what happens past that: windows and doors stay shut, outdoor air intake gets throttled back if the building's system allows it, and a HEPA room purifier or a space fitted with a MERV 13 filter runs until the line drops.
A reading does not close a damper or run a purifier by itself. Somebody still has to act on it, which is why the response belongs in the program before the smoke arrives, not during it.
Give the program a baseline period before you trust it
A single morning tells you about that morning, not about the month. A baseline needs to run long enough to see a normal week play out: a packed Monday, a quiet Friday, a carpet crew that leaves VOCs off-gassing for days afterward. Four to six weeks is a reasonable floor, long enough to see one full occupancy cycle in most office buildings.
A school or a seasonal building needs a baseline that spans the season that actually concerns it: a flu season, a wildfire season, or a summer when the air handler struggles to keep humidity down.
Log tenant complaints against a reading, not a memory
When a tenant says a floor is stuffy, pull up the CO₂ and PM2.5 history for that room and that day instead of relying on who remembers what. Either the room was in range the whole time, which is itself an answer, or the reading shows exactly when it moved and by how much.
Keep the log by room, not by building. A complaint about the third floor should pull up the third floor's own history, not an average across six floors that hides it.
Budget a building air quality program per space
A program priced per building charges the same whether it covers two conference rooms or twenty occupied floors. A program sized per space scales with what needs covering instead, with no minimum term tying a building to more monitoring than it has rooms for. Measured Air's page for commercial buildings prices this way, and replies to a short form within a business day.
Budget for monitors in the rooms people occupy first, then expand to common areas once the baseline in the main spaces is established.
FAQ
What should a building air quality program measure? A building air quality program should measure CO₂, PM2.5, VOCs, relative humidity and temperature in every occupied room, each checked against the air outside that day.
How many air quality monitors does a building need? One per occupied space type, not one for the whole floor. A loud mechanical room reads nothing like the quiet office next to it, and a single hallway monitor hides whichever space actually has the problem.
What is a good CO₂ level for an office building? A good CO₂ level for an office building stays under roughly 1,000 to 1,100 ppm, the range ASHRAE's position treats as the sign that outdoor air ventilation is keeping up with occupancy.
How long before a building's air quality baseline is reliable? A building's air quality baseline becomes reliable after about four to six weeks, long enough to see a full occupancy cycle, including whatever a cleaning crew or a renovation adds to VOCs along the way.
Does OSHA require a building air quality program? No. OSHA has no general indoor air quality standard and does not require ongoing monitoring; it relies on the general duty clause after a complaint, not a program run ahead of one (OSHA indoor air quality standards).
Can a monitor settle a tenant air quality complaint? Yes, if the reading was already running before the complaint came in. Pulling up the CO₂ and PM2.5 history for that room and that day either confirms the room was in range or shows exactly when and how far it moved, which a memory of the day cannot do.
The next step for a facilities team
A building air quality program comes down to four decisions made before the first complaint: what to measure (CO₂, PM2.5, VOCs, humidity and temperature against the outdoor air), where monitors go (every occupied room, not the lobby alone), how long to run a baseline before trusting it (four to six weeks, a full occupancy cycle), and what happens the first time a reading crosses the line you set. None of that replaces a facilities team's own judgment. A monitor reports what a room is doing; somebody still has to adjust the ventilation schedule, run a HEPA room purifier, or decide the room was fine all along.
What a program replaces is the guesswork between a complaint and an answer. A building with a program already running meets the next "the third floor feels stuffy" with a number instead of a promise to look into it. Buildings ready to start can fill out a short form on Measured Air's page for commercial buildings; Measured Air replies within a business day.