Poor indoor air quality
Poor indoor air quality — measure, explain, resolve
Bad indoor air quality is rarely caused by one thing. Continuous monitoring, targeted sampling and ventilation review separate occupancy-driven CO₂ build-up from chemical, particulate or comfort issues — and turn vague complaints into prioritised actions.
Signal bands
What the data typically shows
Most poor IAQ findings fall into a small number of recognisable patterns. Categorising the data is the first step toward a fix that lasts.
Within targets
No further action; baseline established.
Edge of target
Operational tuning of ventilation or cleaning.
Exceeds targets
Targeted intervention required.
Sustained breach
Engineering or remediation programme.
Cause attribution
Correlating sensor data with occupancy, HVAC mode and weather isolates the real driver.
Ventilation gap analysis
Measured fresh-air supply against BS EN 16798 and CIBSE TM40 design targets.
Pollutant breakdown
Speciated VOCs, particulates and formaldehyde where occupant complaints suggest chemistry.
Prioritised actions
A short, ranked list of interventions with expected impact and cost order of magnitude.
When this applies
Typical poor IAQ scenarios
Stuffy meeting rooms, drowsy afternoons, post-refurbishment chemical smell, persistent humidity or condensation, complaints concentrated in one zone, or a known ventilation underperformance. All are routinely diagnosed with a short structured monitoring exercise.
Pair with indoor air investigations, indoor air pollution testing and indoor air quality monitoring.
Benchmarks
Reference targets for healthy indoor air
| Parameter | Target | Reference |
|---|---|---|
| CO₂ | < ~800 ppm above outdoor | BS EN 16798-1 Cat II |
| PM2.5 (24-h) | < 15 µg/m³ | WHO 2021 |
| TVOC | < 500 µg/m³ | WELL v2 Air |
| Formaldehyde | < 100 µg/m³ (30-min) | WHO IAQ guideline |
| Temperature | 21–23 °C | CIBSE Guide A |
| Relative humidity | 40–60 % | CIBSE Guide A |
Find out why air quality is poor
Short, structured monitoring and a clear written report with prioritised actions.
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Measurement