• Elimination of a hazardous technique, process, or material
• Substitution of a less hazardous technique, process, or material for a more hazardous one
• Segregation of people from hazards
• Enclosure of hazards
• Ventilation of the workplace and the source of contaminants
• Repair or replacement of faulty equipment or machinery

Engineering controls are usually the most effective way to protect all laboratory workers because they make changes at the source of the hazards and don't rely on the skill or vigilance of individuals. Engineering controls are often used along with administrative measures and personal protective equipment.

The following engineering controls are in use at UCSD:

Building ventilation	Building ventilation provides UCSD laboratories with at least 10 air changes per hour (ACH) of fresh (outside) air. This airflow reduces employee exposure to airborne contaminants and removes excess heat. It also directs the airflow from areas of lower hazard to areas of higher hazard, which helps keep odors and hazardous gases, dusts, and vapors out of hallways and other public areas.
Local exhaust systems and fume hoods	A local exhaust system has a hood that captures contaminants at their source before they escape into the workroom environment. To be effective, the hood must be within 10–12 inches of the source (closer is better). Drafts, traffic, and heating sources can impair the effectiveness of a local exhaust system. Chemical fume hoods contain hazardous dusts, gases, vapors, and fumes that are generated within them and remove them via the building's ventilation system. When used properly, these hoods are extremely effective at protecting lab workers and the work environment, although they should not be used with biohazardous materials. Wash-down fume hoods, for use with perchloric acid, are fitted with sprinklers to prevent explosive perchlorate crystals from forming. "Snorkels" or "elephant trunks" are exhaust systems intended for small areas or machines.
Biosafety cabinets (BSCs)	Biosafety cabinets use HEPA filters to protect lab workers and the environment from aerosols or droplets that could spread biohazardous material.
Shielding for radiation	Radiation shielding varies from lead bricks to plastic (Lucite) panels, depending on the type of radiation involved. Different thicknesses of these materials are used, depending on the energy of the radiation.
Shielding for blood and body fluid splatter	This physical barrier is especially useful for opening vacutainer tubes or other potential splatter activities.
Glove boxes	Glove boxes are airtight boxes with 2 or more heavy rubber gloves and an airlock. Use them when working with known carcinogens and highly toxic substances, or to provide an inert atmosphere for compounds that are sensitive to water or air. Glove bags are an economic alternative for short-term uses.
Gas cabinets	Use gas cabinets to house hazardous gas cylinders, such as hydrogen or arsine. Cylinders containing nontoxic, oxidizing, or flammable gas used in fume hood applications do not require the use of a gas cabinet. In some cases, pyrophoric, corrosive, and toxic gases may be kept in a fume hood.
Clean benches	Also called laminar flow benches, clean benches DO NOT protect people or the environment. Their only purpose is to provide a clean, HEPA-filtered work area. They do not recirculate or filter air. If you work with hazardous materials, use a fume hood or biosafety cabinet instead.

If you're a UCSD employee and have questions, contact an EH&S Research Assistance Program specialist.