Embedded Files
In preventing exposure to harmful substances in the workplace, there is a hierarchy of control measures that must be considered as defined by the Occupational Safety and Health Administration (OSHA), which includes the use of engineering controls, such as local exhaust ventilation (LEV). LEV is an engineering system designed to reduce employee exposure to airborne contaminants (dust, mist, fume, vapor, gas) in the workplace by capturing/containing the emission at source and transporting it to a safe emission point (i.e., outside exhaust, filter, scrubber, etc.). Thus, LEV prevents exposure to hazardous substances by preventing their release into the workplace atmosphere.
When using an LEV system to control exposure, an employer must thoroughly assess the hazards to be controlled while evaluating if the LEV system: (1) is properly designed for the purpose; (2) is being used correctly by the employees; (3) undergoes preventative maintenance to remain effective; and (4) records are kept to demonstrate that the system is both effective and ongoing.
The primary elements of LEV system include:
1. An inlet/enclosure/hood (e.g., flanged, conical, slot, laboratory fume, etc.) where the contaminant is captured or contained and enters the LEV systems.
2. Ducting which transports air/contaminant from the hood to the discharge point.
3. Air cleaner/filter which ‘scrubs’ the extracted air (note: not all systems need an air cleaning/filtration system).
4. Air mover which is a fan and motor that powers the system and creates a vacuum to displace the air.
5. A discharge or exhaust point which releases the extracted air to a safe place.
AM H&S provides testing to evaluate the effectiveness of the system against published guidelines (i.e., ACGIH, ANSI/AIHA, etc.) and to confirm that the respective LEV system and hood design is working properly. This typically is expressed as a measured average face velocity and/or average capture velocity. Our LEV testing is carried out by qualified health and safety associates/industrial hygienists with experience and training in the use of tools and proper measurement techniques to perform this service.
Page updated
Report abuse