Ventilation

One of the most commonly used means for controlling chemical and biological hazards at work is ventilation. There are two forms of ventilation control; local exhaust (LEV) and general dilution (GDV). LEV relies on extracting airborne contaminants from as close as possible to the source, for example hoods over welding benches; lip extraction around degreasing tanks; cowls around saws; shot blasting cabinets; etc.

GDV relies on diluting airborne contaminants with fresh, clean air. This means that contaminants may be dispersed across the workplace, but they will be very diluted. GDV is adequate for removing odours and workplace heat, but is not effective for controlling exposure to hazardous substances.

COSHH Regulations require LEV systems to be fully examined every 14 months. Also, there is a responsibility for routine inspections to be carried out at a frequency which depends on the substances being controlled. In general, formal weekly visual inspection of systems is suitable but this may alter between monthly for some systems and daily for others. Certain systems, such as shot or grit blast units, require detailed monthly checks.

Drivers

The Control of Substances Hazardous to Health Regulations, 2002 and 2004 (Amendment)