Practical guideline for indoor air quality in work areas in Belgium: Analysis

The Belgian Practical Guideline for Indoor Air Quality in Workplaces was developed to clarify the Codex's provisions on well-being at work and to protect employees by ensuring good air quality. The guideline is primarily intended for prevention advisors, but also contains useful information for employers, employees, and building managers. A workplace is any room with a workstation, such as offices, meeting rooms, or classrooms.

Part 1: Risk Analysis, CO₂ Standards, and the Focus on Measurement

The core of the guideline is conducting a risk analysis of indoor air quality, taking into account the flow rate of the supplied air and potential sources of contamination. This process helps identify sources of contamination, going beyond simply meeting limit values.

Risk Aspects of Indoor Air Quality

Factors that influence air quality include: ventilation, contamination from people, materials and equipment, maintenance, and the quality of the supplied outdoor air. Pollution by People: People produce CO₂ and other bioeffluents (odors, skin flakes). The CO₂ concentration is used as an indicator or proxy for this difficult-to-measure pollution. The nominal CO₂ production for light office work is estimated at $20 l/hour per person. Inadequate ventilation leads to high concentrations of microorganisms (viruses, bacteria), which can cause infections and allergic reactions.

Impact on Employees: High CO₂ concentrations decrease attention, concentration, and work speed. This leads to more errors, decreased productivity, and increased absenteeism.

CO₂ Standards and Ventilation Requirements (Flow Rate)

The Codex sets requirements for ventilation at two levels of CO₂ concentration, depending on the type of room:

General Requirement (Other Rooms): The CO₂ concentration must generally be lower than 900 ppm (or 500 ppm above the outdoor air concentration). This requires a minimum ventilation flow rate of 40 m³ per person.

Rooms with Reduced Sources of Pollution: These are rooms where sources of pollution have been significantly reduced (for example, floor coverings that meet emission standards). A limit of 1200 ppm (or 800 ppm above the outdoor air concentration) applies here. This requires a minimum flow rate of 25 m³ per person.

"Usually" means that the concentration must remain below the limit for 95% of the time of use (maximum over a full working day).

Measurement Method (CO₂ and Installation)

When risks cannot be ruled out through screening or calculations, measurements are required.

CO₂ measurements should be taken centrally at a height of 1 to 1.5 meters in rooms up to 50m². Multiple measurements are required for larger rooms.

A distance of at least 1.5 meters must be maintained between the CO₂ sensor and any occupants, as well as between the sensor and the fresh air intake. This is to avoid direct contact with exhaled or supplied air.

The measurement should be taken at the end of the workday or just before a break to determine the highest plateau value (balance between supply and exhaust).

Long-term CO₂ measurements (at least a full workday) provide the best picture of ventilation effectiveness.

The RoomYou1 sensor, a mobile and accurate monitor, allows you to take the required measurements at the correct height and distance, and to store the long-term data for analysis.

Part 2: New Construction, Existing Construction, and the Role of Technical Measures

Approach in New Construction

The design of a new building follows a structured process (commissioning) to ensure good air quality:

Determining the nominal occupancy.

Checking whether the room meets the requirements for low-emission materials (to allow for a lower airflow rate of 25 m³ per person).

Design and installation of a ventilation system capable of delivering the required airflow.

Commissioning (test phase): Demonstrating that the airflow rates have actually been achieved in practice.

The ventilation system must be controllable, preferably based on the number of occupants or the CO₂ concentration in the room (demand-driven ventilation).

Approach in Existing Buildings

In existing buildings, a risk analysis begins (screening, calculations, and measurements if necessary). If necessary, an action plan with technical and organizational measures follows.

Technical Measures: This includes limiting sources of pollution (choosing low-emission materials). Improving an existing ventilation system involves repairing faults (leaks, defective valves) and performing maintenance (filters, cleaning).

Organizational Measures (Short-Term Action): This is often the only way to achieve rapid improvement. This includes limiting the number of people present in the room and implementing permanent or regular ventilation (opening windows), especially if the ventilation capacity is insufficient. CO₂ sensors in the room can help tailor window openings to specific needs.

The RoomYou1 sensor, with its CO₂ measurement function, is an immediate, effective tool for these organizational corrective measures.

Jille Kuipers, Innovation Manager at LuxBalance, on the focus on CO₂ measurement and flexibility:

"The Belgian guideline is one of the most detailed, as it very explicitly describes the steps in the risk analysis. The key message for practice is twofold: first, you must use the CO₂ proxy to prove compliance with the 900 ppm or 1200 ppm requirement. Second, the placement of the sensor is just as important as the sensor itself. The requirement to maintain a distance of 1.5 meters from people and ventilation openings means that a mobile, battery-powered monitor like the Room You 1, which can easily be placed in the optimal location (1 to 1.5 meters high), is crucial for collecting the required, reliable long-term data. Fixed, mains-powered systems often lack this flexibility."

Reference:

Inspectorate for Supervision of Well-being at Work (2019). Practical Guideline for Indoor Air Quality in Workplaces (Version 2-5-2019). Belgium.

The RoomYou1 sensor makes active CO₂ monitoring simple, accurate, and mobile, enabling organizations and schools to comply with all legal and health regulations.