Indoor Air Quality Is More Than Humidity

Clean-looking air is not necessarily healthy air

A room may feel cool, look clean and show a normal humidity reading — yet still have an indoor air quality problem.

This is one of the most useful conclusions from a recent UAE study examining 35 locations at Abu Dhabi University. The research assessed eleven parameters, including temperature, relative humidity, carbon dioxide, particulate matter, formaldehyde, volatile organic compounds, and bacterial and fungal counts.

Most locations met the limits referenced by the researchers. However, the study also found several localised exceedances. These results demonstrate why indoor air quality cannot be judged from temperature or humidity alone.

This study was conducted at Abu Dhabi University and did not test or endorse ONYX NOVA products. Its findings are referenced only to explain why indoor air quality should be assessed across multiple parameters.

What did the UAE study find?

The study, published in Frontiers in Built Environment on 18 August 2026, compared its measurements with the Dubai Municipality Indoor Air Quality Guideline DM-HSD-GU119-IAQ (2024).

Among its findings:

• carbon dioxide exceeded the referenced 800 ppm limit at five high-occupancy locations and reached a maximum of 1,093 ppm;
• formaldehyde reached 0.10 ppm in the main auditorium, compared with the referenced limit of 0.08 ppm;
• elevated bacterial and fungal counts were identified in individual dormitory locations;
• classroom relative humidity generally remained between 46% and 60%;
• most parameters at most tested locations remained within the applicable limits.

The study does not suggest that the whole campus had poor air quality. Instead, it shows that problems can be localised and related to occupancy, ventilation, materials, cleaning conditions or moisture sources.

Why normal humidity does not guarantee healthy air

Relative humidity is an important part of indoor comfort and building protection. Persistently high humidity can contribute to condensation, mould growth, odours and damage to furniture, finishes and stored items.

But humidity does not tell us how much fresh air is entering a room. It also does not measure fine particles, carbon dioxide, volatile organic compounds or microbiological contamination.

For example, a room can remain at an acceptable relative humidity while CO₂ rises because many people occupy the space and the available fresh-air supply is insufficient. Equally, a well-ventilated room may still require better filtration if outdoor dust or fine particles are entering the building.

This is why a single device cannot automatically solve every indoor air quality issue.

Four different problems — four different responses

1. Excessive indoor humidity

When indoor relative humidity remains high, particularly in coastal UAE properties, dedicated dehumidification may be required. The objective is to remove excess moisture independently of the air-conditioning system's normal temperature-control cycle.

ONYX Core and Zenith systems are designed for moisture control in applications where dehumidification is the primary requirement.

2. Insufficient fresh-air ventilation

Elevated CO₂ is often an indicator that the fresh-air supply is not keeping pace with occupancy. The response is not simply to add a purifier or dehumidifier: the ventilation system and actual outdoor-air volume should be assessed.

ONYX Alpha is a fresh-air heat-recovery unit. It is intended to introduce mechanically supplied outdoor air while reducing the thermal impact before that air reaches the occupied space or air-conditioning system. Alpha is not a dehumidifier.

3. Airborne particles and odours

Dust, fine particles and certain gaseous contaminants require suitable filtration. Filter selection should reflect the target pollutant, airflow, pressure drop, system configuration and maintenance requirements.

ONYX Aura provides active electrostatic air purification integrated at the return-air side of a compatible air-conditioning or fan-coil system. Air passes through a washable pre-filter, an ionisation stage and an electrostatic collection stage, allowing circulating air to be treated without relying on a portable room purifier.

4. Combined fresh-air and humidity requirements

Some projects require more than one function: outdoor-air supply, exhaust, filtration and humidity management. These applications should be assessed as complete air systems rather than as a collection of unrelated devices.

ONYX Aero and PolarStar are intended for projects where fresh-air treatment and humidity control need to be considered together. Final equipment selection depends on airflow, occupancy, outdoor-air volume, duct configuration and site conditions.

Start with diagnosis, not equipment

Before recommending a solution, the building should be assessed for the problem actually present. A practical initial inspection may include:

• relative humidity and temperature measurements;
• CO₂ readings in occupied rooms;
• PM2.5 and PM10 measurements;
• review of fresh-air provision and extract ventilation;
• inspection for condensation, water ingress or hidden moisture sources;
• review of AC filters, ducts and maintenance history.

Formaldehyde, VOC or microbiological testing may require suitable instruments or an accredited laboratory, depending on the purpose of the assessment.

Measurements should also be interpreted in context. A single reading taken in an empty room cannot necessarily describe conditions during peak occupancy, and a short humidity measurement may not reveal a recurring overnight or seasonal problem.

A complete indoor-air strategy for UAE buildings

In the UAE, air conditioning, humidity control, fresh-air ventilation and filtration are closely connected, but they do different jobs.

A robust strategy therefore begins with three questions:

1. Is there excess moisture that needs to be removed?
2. Is the building receiving enough mechanically supplied fresh air for its occupancy?
3. Which particles or pollutants must the filtration system address?

The answers determine whether the property needs dehumidification, improved ventilation, enhanced filtration or a combination of these measures.

ONYX NOVA assesses the building first and then recommends the appropriate system configuration for the property and its HVAC arrangement.

Concerned about humidity, stale air or indoor air quality in your property?

Book an ONYX NOVA inspection to assess the symptoms, existing ventilation and HVAC configuration before selecting a solution.

References

Qafisheh, N. and Kour, H. (2026). "Campus-wide assessment of indoor air quality at a university in the United Arab Emirates." Frontiers in Built Environment, 12:1905303. Published 18 August 2026. https://doi.org/10.3389/fbuil.2026.1905303

This study was conducted at Abu Dhabi University and did not test or endorse ONYX NOVA products. Its findings are referenced only to explain why indoor air quality should be assessed across multiple parameters.