Fume hoods contain potentially dangerous vapors, exhaust, or fumes to filter the air and vent it to a safe location. Ducted fume hoods connect to a facility ventilation system to exhaust filtered air outdoors. Ductless hoods filter air and return it to the workspace, so they're used for nonflammable, nontoxic nuisance vapors. Biosafety cabinets and enclosures are used in biological testing applications. Glove boxes and chambers allow workers to manipulate samples in an entirely sealed environment to reduce cross-contamination. Exhaust snorkels and portable fume extractors pull aerosols, fumes, and vapors from the air. Fume hood cabinets keep supplies close at hand. Filters capture particles as they're pulled from the cabinet. Work surfaces protect against damage caused by harsh chemicals and ease cleaning. Airflow monitors ensure airflow meets required safety specifications. Blowers move air through the hood. Accessories (such as tubing and lighting) help keep equipment in good working order.