Poor & Bad Indoor Air Quality
Poor indoor air quality.
Poor indoor air quality is the largest controllable driver of headaches, fatigue and absence in UK workplaces. We diagnose it with independent, evidence-grade testing — and tell you exactly what to fix.
Recognising the problem
What poor and bad indoor air quality actually looks like
Poor indoor air quality rarely announces itself. It surfaces as a slow accumulation of complaints — headaches by mid-afternoon, dry eyes by Wednesday, a wave of throat irritation after the heating is switched on for winter. Individually each complaint can be dismissed. Plotted together against occupancy, ventilation and pollutant data, the pattern is unmistakeable.
Bad indoor air quality in commercial buildings is almost always a combination of under-ventilation and uncontrolled emission sources. The building was sized for one occupancy, densified for another, and never recommissioned. Filters are overdue. Supply diffusers were blocked by partitions during the last churn. New furniture and finishes are still off-gassing. Each effect is small. Together they push the building outside its design envelope.
The first step is measurement. Without continuous data at the breathing zone, every conversation about poor IAQ becomes a question of opinion. Once the data is on the table, the remediation plan usually writes itself.
Investigation
How we diagnose poor indoor air quality
- 1
Stage 01
Symptom & complaint review
Anonymous occupant survey, review of FM and HR complaint logs, refurbishment history and HVAC commissioning records to scope the problem.
- 2
Stage 02
Walk-through inspection
Visual audit of AHUs, filter condition, supply/extract terminals, occupancy density, finishes and known emission sources (printers, kitchens, cleaning stores).
- 3
Stage 03
Continuous monitoring
Research-grade sensors for 5–10 working days measuring CO₂, PM2.5, PM10, TVOC, temperature and RH at breathing height. Sorbent tubes for formaldehyde and speciated VOCs where indicated.
- 4
Stage 04
Report & remediation plan
Findings benchmarked against BS EN 16798-1, CIBSE TM40 and WHO IAQ Guidelines, with ranked, costed remediation options and a verification re-test scope.
Benchmarks
When indoor air quality counts as poor
| Parameter | Good | Poor / bad IAQ |
|---|---|---|
| CO₂ (above outdoor) | < 800 ppm | > 1,000 ppm sustained |
| PM2.5 (24-h) | < 10 µg/m³ | > 25 µg/m³ |
| TVOC | < 300 µg/m³ | > 500 µg/m³ |
| Formaldehyde | < 50 µg/m³ | > 100 µg/m³ |
| Relative humidity | 40–60% | < 30% or > 70% |
| Temperature (winter) | 21–23 °C | < 19 °C or > 25 °C |
The cost of inaction
Why poor indoor air quality is a board-level issue
The financial impact of bad indoor air quality is well documented. The Harvard COGfx work and CIBSE TM40 both show measurable productivity loss when CO₂ rises above 1,000 ppm or PM2.5 climbs into traffic-pollution territory. The HSE has been increasingly explicit that, once symptoms are reported, employers are expected to demonstrate a documented IAQ assessment.
The reputational impact is harder to quantify but easier to feel. A workplace that produces a Sick Building Syndrome cluster, a union grievance or a public-facing complaint about poor office air quality rarely recovers occupant trust without independent test data and a visible remediation programme.
The good news is that the remediation costs are usually modest relative to the avoided loss. Increased fresh-air rate, filter upgrade, supply-terminal repositioning and a targeted source-removal programme typically remove 70–80% of measured pollutants inside two weeks.
FAQ
Poor indoor air quality — common questions
Concerned about poor indoor air quality in your building?
Book an independent IAQ assessment — typically scheduled within 10 working days. Call 01322 555566 or email info@sickbuildingsyndrome.uk.
Book an assessmentRelated investigations
Measure the building
Talk to a specialist