Research project interference factors: Movement in the laboratory

Dynamic interference and its impact

Research for a safer laboratory:

Safety cabinets (SCs) are an important protective device in many biotechnological and pharmaceutical laboratories for the safe handling of hazardous substances or dangerous biological agents. The protective functions they provide are based on directional, balanced ventilation flows in the protected work area. They ensure that particulate releases do not reach the user (personal protection) and airborne contaminants are kept away from sensitive materials (product and carry-over protection).

These protective functions are tested in accordance with the currently valid standards using a microbiological test method - but in an empty laboratory. Influences by staff working in the laboratory are not taken into account in the tests. However, people unintentionally generate air movements with every movement and thus easily become a "disturbance factor" for the safe operation of a SC. As part of a research project lasting several years, Berner International has tested and quantified the influence of user activities on the protective functions.

The following activities can affect the protective functions of a SC:

Arm movements in the area of the work openings
Walking quickly in front of the SWB (e.g. by the assembler)
Opening and closing doors near SCs

In order to check the effects of user-induced airflow disturbances, the normatively required performance of various SWBs was first tested at the operating point specified by the manufacturer. By gradually reducing the SCs own protective airflows, it was then possible to evaluate the performance limits of the units in the presence and absence of person-induced disturbances. Depending on the model, this revealed very different safety reserves to compensate for the disturbances caused by the user. It could be shown quantitatively that dynamic disturbances in particular can have a considerable influence on the protective functions.

For the proper use of a SC, the following important consequences result from the investigations:

1. The air flows may only be reduced within their individual performance limits. For this, the relevant data from the manufacturer must be requested.

2. Rapid arm movements of the work opening should be avoided.

3. Especially during "critical" phases of use (when hazardous and biological substances are openly handled), no other persons (e.g., assemblers) should be in the vicinity of the SC or move around it.

4. Laboratory personnel should be regularly informed of possible impairment of the protective functions as a result of self-inflicted malfunctions.

5. Within the framework of the normative requirements for the performance of SWBs, person-induced disturbances should be taken into account more than before.