Supervisors must ensure that adequate training is given to new process operatives, to include proper use of the LEV system, any set parameters for use (e.g. the number of open outlets required for optimal performance) and any routine performance checks to be undertaken prior to work starting.
An introduction to LEV video developed by the Health and Safety Executive is the first video below. This video demonstrates how use of local exhaust ventilation as an engineering control can effectively remove harmful dusts, vapours and fumes from the breathing zone of those who carry out non-laboratory type work activities:
The video below, as developed by a US manufacturing company Labconco, demonstrates by using a smoke pencil, how effective extraction using a fume cupboard can be and what can affect extraction efficiency when fume cupboards are in use. This demonstrates some key messages which are highlighted in a separate Fume Cupboard use leaflet.