What indoor air quality (IAQ) is
and why it matters for occupational health.

Indoor Air Quality (IAQ) is a set of parameters that describe air conditions in enclosed environments. Temperature and humidity are part of that set, but they are not the only elements relevant to the workplace.

What IAQ is

IAQ stands for Indoor Air Quality. The term describes air conditions in enclosed environments, considering parameters that affect comfort and occupational health.

The parameters most commonly assessed in workplaces are:

• CO₂, an indirect indicator of the effectiveness of air renewal
• VOCs, Volatile Organic Compounds, present in paints, varnishes, solvents and cleaning products
• Particulate matter (PM2.5, PM10)
• Temperature and relative humidity

Direct CO₂ vs. eCO₂

Two types of measurement are available on the market, and the difference matters:

• Direct CO₂: measured by NDIR (non-dispersive infrared) sensors. Values expressed in ppm (parts per million) with analytical accuracy.
• eCO₂: an estimate of CO₂ calculated from the concentration of VOCs by MOX (metal-oxide) sensors. It is a useful proxy for indicating air-quality trends, but it is not equivalent to a direct CO₂ measurement for the purposes of technical reports or compliance reports that specify limits in ppm.

For applications that require analytical accuracy or formal reports, check which technology the sensor uses.

The relationship with occupational health programs

An occupational health risk program must identify and assess all occupational risks in the workplace, including physical risks (temperature, humidity, noise) and chemical risks (agents present in the air).

Environments with insufficient ventilation, a build-up of VOCs or accumulation of CO₂ may represent health risks that should appear in the risk inventory. Historical data on these conditions helps demonstrate that the risks were assessed and control measures adopted.

CO₂ as a ventilation indicator

In enclosed environments with human occupancy, CO₂ accumulates in proportion to the number of people and inversely to air renewal. High concentrations of CO₂ indicate insufficient ventilation, not necessarily an immediate health risk, but a condition that can compromise workers' comfort and attention.

The international standard ASHRAE 62.1, a reference for ventilation, uses CO₂ as a proxy to assess the adequacy of air renewal in occupied environments.

Thermal-comfort standards deal with ergonomic comfort. Heat-stress and occupational-hygiene frameworks deal with physical and chemical agents with the potential to harm health. For environments with specific chemical agents in the air, the assessment should follow the tolerance limits of the applicable occupational-hygiene framework, not just comfort parameters.