Indoor Air Quality Testing: Comprehensive On-Site Assessments

Every project follows the same five-stage method, scaled to building size.

1. Scoping. A short remote briefing identifies the buildings, complaint history, recent works, HVAC topology and any reporting obligation (WELL, BREEAM, insurer, tribunal). We confirm which pollutants are in scope and where sensors will sit.

2. Mobilisation. Equipment is calibrated against traceable reference gases and aerosols before deployment. Sensors are placed in the breathing zone at occupied positions, not on walls or ceilings where readings drift from what people actually inhale.

3. On-site measurement. Continuous logging spans at least one full occupied weekday, ideally bracketing a weekend so unoccupied baselines are captured. Sorbent tubes run for four to eight hours during representative activity.

4. Laboratory analysis. Tubes are sent to a UKAS-accredited laboratory for thermal desorption GC-MS speciation. Mould samples are read under direct microscopy or culture, depending on whether species or viability matters.

5. Reporting. Results are tabulated against the relevant benchmark, plotted against occupancy and weather, and translated into a prioritised remediation plan. The report is written for facilities managers, not for laboratories — every number carries a sentence explaining what to do about it.

Testing earns its cost in five common scenarios.

Symptom investigation. Occupants report headaches, fatigue, irritation or asthma exacerbation. Testing distinguishes sick building syndrome from genuine pollutant exposure, and identifies which pollutant.

Post-refurbishment. New flooring, paint, furniture or insulation can elevate formaldehyde and TVOCs for weeks. A baseline test before occupants return prevents a wave of complaints.

Ventilation change. After HVAC modifications or a shift to mechanical recovery, measured CO₂ and PM2.5 confirm whether design intent translated into delivered performance. Pair this with a ventilation assessment.

Insurance or dispute. Damp, water ingress and material defects often surface as IAQ complaints. Independent laboratory data is defensible in a way that consumer-grade readings are not.

Certification. WELL v2, BREEAM Hea 02 and RESET Air all require measured IAQ data against specific protocols. The report is structured to satisfy the assessor without rework.

Different pollutants demand different instruments. The right choice depends on what the data has to defend.

Photoacoustic and NDIR sensors deliver reference-grade CO₂ and continuous VOC trends. They are the workhorses of continuous monitoring.

Laser optical particle counters resolve PM1, PM2.5 and PM10 with size distributions. Where regulatory defensibility is required, gravimetric impactors run in parallel for cross-calibration.

Thermal desorption GC-MS on Tenax or carbograph sorbent tubes provides the lab-grade speciation that consumer monitors cannot — essential for source attribution and dose reconstruction.

Passive integrators (Palmes tubes for NO₂, sorbent tubes for VOCs) average exposure over weeks or months, capturing seasonal variation that short surveys miss.

Sensor position matters as much as sensor choice. A single rooftop reading cannot diagnose a complaint zone three floors below.

The deliverable is a single PDF, typically 30–60 pages, structured for action rather than archive.

Executive summary. Two pages: the pollutants found above benchmark, the rooms or systems implicated, and the three highest-impact interventions.

Methodology and instruments. Sensor list with calibration certificates, sampling locations on floor plans, and the standards each measurement was assessed against.

Results tables and charts. Continuous data plotted against occupancy and weather, peak and time-weighted averages, and indoor-to-outdoor ratios where relevant.

Findings and remediation plan. Each finding is scored by health impact and remediation cost, then sequenced into immediate, short-term and capital actions. Where possible, we include indicative budget bands.

UK practice draws on a layered set of references. The Workplace (Health, Safety and Welfare) Regulations 1992 and ACOP L24 establish the legal duty for effective ventilation. CIBSE Guide A, TM40 and TM26 give detailed design and operational targets. BS EN 16798-1 sets indoor environmental categories I–IV for non-residential buildings. ASHRAE 62.1 provides per-person and per-area ventilation rates widely used in commercial design.

Health-based references include WHO 2021 global air quality guidelines for PM2.5 (5 µg/m³ annual), NO₂ (10 µg/m³ annual) and ozone. Voluntary frameworks — WELL v2, BREEAM, RESET Air — sit on top of these and add monitoring, transparency and material requirements.

The report makes the chosen benchmark explicit for every measurement, so the reader knows whether they are looking at a legal limit, a health guideline or a best-practice target.

A report that never leaves a server is wasted work. We support three follow-on patterns.

Workshop. A 90-minute session with the facilities team and senior stakeholders, walking through the findings, agreeing the remediation sequence and assigning owners.

Re-test. After source-control and ventilation changes, a focused re-measurement quantifies the improvement. This is the only honest way to confirm remediation worked.

Transition to monitoring. Where the building benefits from continuous oversight — high churn, certification, vulnerable occupants — we hand the test data into a permanent monitoring programme.