Office Air Quality: How to Test, Understand, and Improve the Air at Work

You know the feeling. It is 3pm, you have been in a conference room for 45 minutes with seven other people, and everyone is losing focus. Someone opens a window, someone else suggests a break. The meeting was fine at 2:15. What changed?

In many cases, the answer is CO2. A room full of people breathing in a space with inadequate ventilation can push carbon dioxide levels past 2,000 ppm within half an hour. At those concentrations, your ability to make complex decisions measurably declines.

This article covers what is in your office air, how to test it without expensive equipment, and what actually improves it.

What is in office air

Three pollutants matter most in a typical office environment:

CO2 from breathing. This is the dominant indoor-generated pollutant in offices. Every person exhales roughly 36 grams of CO2 per hour while doing office work (Persily and de Jonge, 2017). In a well-ventilated space, this is diluted fast enough to stay below 1,000 ppm. In a crowded meeting room with the door closed, it accumulates quickly.

PM2.5 from outdoor infiltration and indoor sources. Fine particles enter from outside (traffic, construction, wildfires) and are generated inside by printers, cleaning, and occasionally cooking in office kitchens. Buildings near busy roads can have significantly elevated indoor PM2.5.

VOCs from furniture and products. Office furniture, carpeting, printers, dry-erase markers, and cleaning products release volatile organic compounds. New offices or recently renovated spaces tend to have higher VOC levels due to off-gassing.

CO2 and your brain: what the research shows

The connection between elevated CO2 and reduced cognitive performance is well-documented.

A 2023 meta-analysis of 15 studies found that CO2 concentrations between 1,000 and 1,500 ppm significantly impaired complex cognitive tasks, with a standardized mean difference of -2.044. This includes tasks like strategic thinking, information processing, and decision-making.

This means that decisions made in a stuffy conference room may be objectively worse decisions than the same ones made at your desk with a window open. This is not a comfort issue. It is a performance issue.

The 1,000 ppm myth

You will often see 1,000 ppm cited as the "safe limit" for indoor CO2. This is a misunderstanding.

ASHRAE Standard 62.1, the primary ventilation standard for commercial buildings, does not contain an indoor CO2 concentration limit. It has not contained one for almost 30 years (Persily, 2021). The 1,000 ppm figure was originally a ventilation adequacy proxy, not a health threshold. ASHRAE removed it because of persistent confusion about what it meant.

What ASHRAE 62.1-2022 does specify is a CO2 differential, the difference between indoor and outdoor CO2. The guideline rounds to the nearest 300 ppm above ambient (assumed to be roughly 400 ppm outdoors). This translates to approximately 700 ppm in most practical settings.

The takeaway: 1,000 ppm is not a magic number, but the cognitive research suggests that staying below it is a reasonable target for office spaces where people need to think clearly.

The meeting room problem in numbers

ASHRAE recommends 7.5 liters per second per person of outdoor air for offices. At this ventilation rate, steady-state CO2 reaches roughly 1,000 ppm above outdoor levels (about 1,400 ppm total). Many meeting rooms do not achieve this rate, especially when they are fully occupied.

In an under-ventilated meeting room with 8 or more people, CO2 can reach 2,000 to 3,000 ppm within 30 to 60 minutes. At those levels, the cognitive impairment research suggests measurable effects on decision quality.

How to test your office air quality

You do not need an industrial hygienist to get useful data about your office air. Here is what to measure and how:

CO2

This is the most actionable measurement for offices. A dedicated CO2 monitor or a multi-parameter air quality monitor gives you real-time readings.

What to look for:

• Open-plan desk area: should stay below 800 to 1,000 ppm during normal occupancy
• Meeting rooms: check 30 and 60 minutes into a typical meeting with the door closed
• If you consistently see numbers above 1,200 to 1,500 ppm, ventilation is inadequate for the occupancy

PM2.5

A PM2.5 sensor shows you whether outdoor pollution is infiltrating effectively (it often is) and whether indoor sources like printers or cleaning are contributing.

What to look for:

• Consistent readings above 12 µg/m³ suggest either poor filtration of outdoor air or an indoor source
• Spikes correlated with specific activities (cleaning, printing, cooking in the kitchen) point to source control opportunities

VOCs

Harder to interpret because general VOC sensors cannot identify specific compounds. But elevated readings that persist even when the space is unoccupied suggest off-gassing from materials. Readings that spike during occupancy may indicate cleaning products or personal care products.

A practical testing approach

Bring a portable monitor to work. Place it at your desk for a full workday to establish a baseline. Then take it to your next meeting room session. The contrast between open-plan and enclosed meeting room readings is usually striking.

The plants myth: why a ficus will not fix your office air

"Best plants for office air quality" is one of the most searched queries about office air. The answer is straightforward: plants do not measurably affect office air quality.

A 2024 controlled field study introduced plants into real offices and measured CO2 levels before and after. The result: "CO2 concentration did not change significantly with the introduction of indoor plants."

The math makes this predictable. One person doing office work generates roughly 36 grams of CO2 per hour. A well-lit houseplant absorbs 50 to 200 milligrams per hour. You would need hundreds of plants per person to make a dent, and most office plants sit in low light where they absorb even less.

Plants in offices provide real benefits: they reduce stress, improve mood, and increase workplace satisfaction. These are worth having. But if your meeting room CO2 is hitting 2,000 ppm, a peace lily is not the solution. Ventilation is.

For a deeper look at the science, see our full article on whether plants clean indoor air.

What actually improves office air quality

1. Increase ventilation

This is the single most effective intervention for CO2 and VOCs. Options depend on your building:

• Open windows. The simplest solution where available. Even opening windows for 10 minutes between meetings dramatically reduces CO2.
• Adjust HVAC. If you have facilities management, ask about increasing the outdoor air fraction in the HVAC system. Many systems are set to minimize energy costs, which often means minimum outdoor air.
• CO2-based demand-controlled ventilation (DCV). This is ASHRAE's recommended approach for variable-occupancy spaces. The system increases ventilation automatically when CO2 rises, directing airflow where people actually are rather than ventilating empty rooms.

2. HEPA air purifiers for PM2.5

Portable HEPA air purifiers effectively remove fine particles from indoor air. For offices near busy roads or in areas with wildfire smoke risk, a HEPA unit in the workspace makes a measurable difference.

Size the purifier appropriately. Look for units with a Clean Air Delivery Rate (CADR) sufficient for your room size.

3. Source control

• Move printers to ventilated areas rather than open-plan spaces
• Use low-VOC cleaning products
• Ensure office kitchens have functioning exhaust ventilation
• Allow new furniture to off-gas in a well-ventilated area before deploying it in occupied spaces

4. Monitor continuously

Spot-checks are useful for identifying problems, but continuous monitoring reveals patterns that single measurements miss. CO2 might be fine at 9am and problematic by 2pm. PM2.5 might spike every Tuesday when the cleaning crew comes through. Without continuous data, these patterns stay invisible.

Making the case to facilities management

If your data shows problems, here is how to present it effectively:

Lead with numbers, not feelings. "The meeting room hit 2,300 ppm CO2 by 3pm on Tuesday" is more actionable than "the conference room feels stuffy."

Connect to productivity. The cognitive performance research is compelling. Framing poor air quality as a productivity issue rather than a comfort issue gets different traction with decision-makers.

Propose specific, measurable changes. "Can we increase the outdoor air damper setting in the west conference room?" is more useful than "we need better air quality."

Offer to provide data. Many facilities teams do not have air quality data for individual rooms. Offering to share your monitoring data gives them information they can act on.

The bottom line

Office air quality directly affects how well you think, especially in meeting rooms where CO2 accumulates quickly. The fix is usually ventilation, not plants.

Testing is simple: bring a CO2 and PM2.5 monitor to your workspace, measure for a day, and take it to your next meeting. The data speaks for itself.

Partycle fits on a desk or conference table. Bring it to your next meeting, watch the CO2 climb, and show your facilities team the data.

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Sources

• Persily, A. and de Jonge, L. (2017). "Carbon dioxide generation rates for building occupants." Indoor Air, 27(5), 868-879. onlinelibrary.wiley.com
• Persily, A. (2021). "Development and Application of an Indoor Carbon Dioxide Metric." ASHRAE Journal. PMC 8596488
• CO2 cognitive meta-analysis (2023). 15 studies on CO2 and cognitive performance. Science of the Total Environment. sciencedirect.com
• Office plants and CO2, 2024 field study. PMC 11253968
• ASHRAE Standard 62.1-2022 (Addendum ab). CO2 differential limits and ventilation requirements. ashrae.org
• ASTM D6245. Standard reference for CO2 generation rates by activity level, gender, body mass, and age.