Engineering Controls > Supplied Air Islands
Island (SAI)/Laminar Flow Systems
Supplied-air islands provide a zone of clean air at a workstation. The supplied
air may come from outside the plant or
the air may be filtered plant air.
Supplied-air islands are especially useful in limiting lead exposure when:
- An employee remains in a
stationary position at the workstation for long periods
of time. The SAI provides an envelope of clean air to a
worker. The clean air flows down over the worker which
normally keeps factory air from entering the clean air
- A supply of fresh, clean air is
available. Note: Outside air may not require cleaning and costs
will be lower. If no outside source of clean air is
available, intake air should be filtered).
- The air is tempered. Employees will not remain in an
environment that is too hot or too cold. Note: If the air
is not tempered employees will block off the air flow with
cardboard or other material in the winter or try to
increase the flow for cooling in the summer which could
result in higher exposures.
The supplied-air island (SAI) should be designed to
provide a laminar flow of fresh air through
the employee's breathing zone at a low enough velocity so that
additional airborne lead dust is not generated through reentrainment.
The SAI height is typically 80 inches from the floor but is often
restricted by overhead clearance limits and other equipment
installed in the area. The air flow is designed so that the velocity
measured at the employee's breathing zone is 100-150 feet per
minute. Higher velocity may stir up lead dust. SAIs can be used in
conjunction with exhaust- ventilated work benches. In this case, the air should be balanced so that make-up
air is provided equal to the amount of the exhaust air.
Using clean air rooms can effectively lower
lead exposure. Some clean air rooms are used as lead-free environments
where employees can remove their
respirators. These rooms need to have positive pressure,
be tempered, and have a filtered air system with a HEPA
filter designed to remove 99.97 percent of lead dust
greater than 0.3 micron in diameter. An ante room
should be included to give employees a place
to remove their protective equipment without spreading
contamination in the clean air rooms.
Perform the following to ensure clean air rooms are free of lead
- Vacuum enclosures and scrub with soap and water so lead dust does not collect on
- Ensure the structural integrity
of all enclosures is intact and under positive
pressure at all times.
- Develop a preventive
maintenance checklist that includes schedules for:
- Replacing ventilation system filters
- Replacing ventilation system
hoses, clamps, and blower internal parts
- Replacing window and door
- Checking and replacing air
shower ventilation systems, including
automatic doors, blower, nozzles, and lighting.
- Monitoring intake and
exhaust airflow to ensure that the rooms are under
positive pressure at all times.