Engineering controls

Engineering controls rank high in the Hierarchy of controls because they protect everyone nearby, all the time, and do not depend on the memory or comfort of the individual. They can be built into a new process, or added to an existing one as a retrofit.

For airborne chemicals, typical choices are enclosing the process, using Local exhaust ventilation (LEV) to capture vapor or dust at the point where it is released, or working inside a Chemical fume hood. General dilution ventilation brings in fresh air to lower the concentration across a room but is less effective for highly toxic materials. For liquids, closed-loop transfer, pumps instead of pouring, and drip trays reduce splashing and spills.

Other examples include substituting a dust-free form of a product, using automation so people are out of the area, and installing interlocks and alarms. Engineering controls need maintenance, as filters clog, fan belts slip and sashes get left open. Checks and measurements of airflow confirm that they are doing their job.

Compare exposure results with limits such as the Permissible exposure limit (PEL) or Threshold limit value (TLV) to see whether controls are adequate. Where controls cannot achieve this, additional measures including Personal protective equipment (PPE) and a Respirator program may be required. The SDS often suggests suitable controls in Section 8, but a workplace assessment decides what is needed.