When planning a workspace where negative handling
will take place, have a preliminary assessment of the existing ventilation system
conducted by a certified industrial hygienist. The assistance of the building maintenance
manager would be desirable.
Air inlets or supply vents set near the ceiling in a closed room provide little,
if any protection for employees working with contaminants at an examining table
or workstation. Contaminants (gases, vapors, etc.) should be removed at their source
to prevent employee exposure.
Often, as was the case at ASM, exhaust vents are improperly located behind a
workstation and cause gases to be drawn form contaminant sources (negatives) and
through the breathing zone of the worker. Ideally, local exhaust ventilation should
be designed to draw air away from the worker's face and breathing zone. Frequently,
slot-type exhausts are placed in front of the employee to facilitate the safe removal
of contaminant materials such as gases.
Many older buildings are cursed with air return systems that recirculate fine
particles of dust and pollutants to the room. Oil-free filters are frequently used
to limit the amount of pollutants entering collection storage areas through ceiling
and wall vents. However, filters covering air vents may impede the building air
conditioning and pressure flow system and decrease necessary ventilation pressure.
Consult your building maintenance manager before applying filters to the existing