ASR A 3.6 Indoor Air Quality Indoor Air Quality
To ensure a good working environment, the indoor air quality must not have a harmful effect on the health of the employees.
In enclosed work spaces, the indoor air must not have a detrimental effect on the health of employees. This is generally the case when the air quality is comparable to the outside air, unless the outside air is polluted. The requirements for indoor air are set out in ASR A3.6 Indoor Air Quality (Chapter 4.1 Principles).
Impairments to indoor air can be caused by moisture loads, heat loads, or material loads, among other things.
Material loads
Material loads can arise, for example, from (Chapter 4.2 Material loads):
- Presence of people (CO2 emissions)
- Emissions from building products or furnishings (VOCs, formaldehyde, fibers, etc.)
- Air from other rooms contaminated by hazardous substances or biological agents
- Poorly maintained ventilation systems
- Mold
An increased concentration of CO2 in the room air (> 1000 ppm) noticeably reduces the attention span and concentration of employees. For this reason, work rooms should be regularly ventilated and the CO2 content reduced to values < 1000 ppm by ventilation systems. The following list shows the measures to be implemented depending on the concentration of carbon dioxide:
< 1000 CO2 concentration in [ml/m3] or [ppm]
- No further measures (provided that no increase in concentration above 1,000 ppm is to be expected due to the use of the room)
1,000 - 2,000 CO2 concentration in [ml/m3] or [ppm]
- Check and improve ventilation behavior
- Draft a ventilation plan (e.g. specify responsibilities)
- Ventilation measures (e.g. increase outside air volume flow or air exchange)
> 2,000 CO2 concentration in [ml/m3] or [ppm]
- Additional measures required (e.g. increased ventilation, reducing the number of people in the room)
Moisture loads
In some work processes, water vapor is released, which can increase the moisture loads. Active humidification of the room air is generally not necessary, unless employees experience discomfort. In this case, a risk assessment must be carried out to determine whether and what measures need to be taken (see Chapter 4.3 Moisture loads). The maximum permissible relative humidity depends on the air temperature and is shown in the table below.
Heat loads
Additional heat loads (Chapter 4.4 Heat loads) are caused by devices, machines and artificial lighting sources, among other things. They must be minimized to the necessary extent so that the requirements of ASR A3.5 "Room temperature" are met.
Free ventilation
“Free ventilation” (Chapter 5 Free ventilation) means the exchange of indoor air with outside air. Of the various options, ventilation through the windows is the most common. A distinction is made between shock ventilation (approx. 3 to 10 minutes) and continuous ventilation. In both cases, the window openings must be arranged so that the work rooms can be ventilated evenly. Furthermore, the formation of drafts must be avoided (Chapter 5.2 Requirements for free ventilation). With one-sided ventilation, the supply and exhaust air openings are in an external wall and can be identical. If the supply and exhaust air openings are in opposite external walls or in an external wall and the roof area, this is cross ventilation. The minimum sizes of the opening areas depend on the room volume and are shown in Table 3 of ASR A3.6, Chapter 5.3 “Free ventilation systems”.
There is no fixed rule as to how often and for how long ventilation should take place. In ASR A3.6 (Chapter 5.4 Intermittent ventilation) only orientation values are given.
Technical ventilation
Technical ventilation is always required when sufficient air exchange through natural ventilation is not sufficient. This can be the case, for example, if it is required due to the entry of hazardous substances or if there are many heat sources in the room.
The ventilation system, also known as the air conditioning system, must be designed in such a way that it corresponds to the state of the art and does not itself become a source of danger. Before being supplied, the supply air must therefore be freed of any hazardous substances, bacteria, etc. using a filter (Chapter 6.2 Requirements). The exhaust air flow must then of course be dimensioned in such a way that material, moisture and heat loads are sufficiently removed and the CO2 content is below 1000 ppm. Our page on the subject of laboratories describes the special requirements for laboratory areas.
Air conditioning systems must be regularly maintained and checked (Chapter 6.6 Commissioning, maintenance and testing).
Information for safe laboratory operations
Energy saving in laboratories
Reducing energy consumption in laboratories as much as possible, both to reduce carbon emissions and to reduce costs, is a sensible measure. Since ventilation technology contributes is by far the largest contributor to energy costs, it is inevitably in the focus of energy saving projects. But since lab work involves the handling of hazardous substances on a regular basis, energy saving potential is very limited. The following statement from the Laboratories Department of the German Social Accident Insurance (dated December 5, 2022) highlights the possibilities and risks of deviating from the usual laboratory ventilation standard.