Indoor air quality testing isn’t a single measurement—it’s a comprehensive evaluation of multiple environmental factors that collectively determine whether the air you breathe supports or undermines your health. Understanding what gets measured and why each parameter matters empowers facility managers to make informed decisions that protect occupants and ensure compliance.
Carbon Monoxide (CO): The Silent Killer
Carbon monoxide represents the most immediately dangerous indoor air pollutant. This colourless, odourless gas prevents blood cells from carrying oxygen, causing symptoms ranging from headaches to death.
What gets measured: CO concentration in parts per million (ppm). Why it matters: Levels above 9 ppm over 8 hours violate OSHA standards. Common sources: Gas appliances, vehicle exhaust from attached parking, and malfunctioning HVAC systems
Professional IAQ testing identifies CO sources before tragic consequences occur, with NABL-accredited laboratories providing legally defensible measurements.
Volatile Organic Compounds (VOCs): The Hidden Chemical Soup
VOCs are hundreds of carbon-containing chemicals that evaporate at room temperature, forming an invisible chemical mixture that affects both short-term comfort and long-term health.
What gets measured: Total VOC (TVOC) concentration and specific compounds like formaldehyde, benzene, and toluene. Why it matters: VOC exposure causes eye irritation, headaches, respiratory problems, and some VOCs are known carcinogens—common sources: Paints, carpets, furniture, cleaning products, building materials.
Testing reveals which VOCs exceed safe levels, enabling targeted remediation rather than costly wholesale material replacement.
Particulate Matter (PM2.5 and PM10): The Respiratory Threat
Airborne particles of varying sizes penetrate to different depths in the respiratory system, with smaller particles posing greater health risks.
What gets measured:
- PM10 (particles ≤10 microns): Inhalable coarse particles
- PM2.5 (particles ≤2.5 microns): Fine particles reach deep into the lungs
Why it matters: PM2.5 exposure correlates with cardiovascular disease, respiratory illness, and premature death. Common sources: Outdoor pollution infiltration, combustion processes, poorly maintained HVAC systems
24-hour exposure limits established by regulatory bodies make accurate measurement essential for compliance.
Nitrogen Dioxide (NO₂): The Combustion Byproduct
Nitrogen dioxide forms during high-temperature combustion, causing respiratory irritation and exacerbating asthma.
What gets measured: NO₂ concentration in ppb (parts per billion). Why it matters: Chronic exposure damages lung tissue and increases susceptibility to infection. Common sources: Gas stoves, generators, vehicle exhaust, industrial processes
Testing identifies combustion sources requiring improved ventilation or replacement.
Temperature and Humidity: The Comfort and Health Equilibrium
Thermal conditions affect both occupant comfort and the potential for biological contaminant growth.
What gets measured:
- Temperature: Typically maintained between 20-24°C
- Relative humidity: Optimal range 30-60%
Why it matters:
- High humidity (>60%) promotes mould growth and dust mite proliferation
- Low humidity (<30%) causes respiratory irritation and static electricity
- Temperature extremes reduce productivity and increase HVAC energy costs
Continuous monitoring reveals patterns that enable proactive HVAC optimisation.
Carbon Dioxide (CO₂): The Ventilation Indicator
CO₂ levels don’t directly cause health problems at typical indoor concentrations but serve as an excellent proxy for ventilation effectiveness.
What gets measured: CO₂ concentration in ppm. Why it matters: Levels above 1000 ppm indicate inadequate ventilation, suggesting other pollutants are also accumulating. Normal range: Outdoor air (~400 ppm), well-ventilated indoor spaces (600-800 ppm)
Elevated CO₂ signals insufficient fresh air exchange, often the root cause of multiple IAQ complaints.
Mould Spores and Bioaerosols: The Biological Hazard
Fungal contamination creates serious health risks, particularly for immunocompromised individuals and those with respiratory conditions.
What gets measured: Airborne spore counts and species identification. Why it matters: Mould produces allergens, irritants, and mycotoxins, which can cause respiratory illness. When testing triggers: Water damage history, musty odours, visible growth, unexplained health complaints
Comprehensive testing distinguishes normal background levels from problematic contamination requiring remediation.
The Integrated Picture: Why Multiple Parameters Matter
Individual measurements provide limited insight—comprehensive IAQ testing reveals interactions between pollutants and cumulative health impacts. A building might pass CO testing but fail VOC and particulate tests, creating an unhealthy environment despite meeting one standard.
Professional IAQ testing from specialists like Aeromech ensures ISO/IEC 17025:2017-accredited measurements, providing legally defensible data to support remediation decisions and regulatory compliance.
Understanding what gets measured transforms IAQ testing from a compliance checkbox into a powerful diagnostic tool protecting occupant health and building value.