Work in BSL-4 containment laboratory requires time and great attention. The same work that is done in a BSL-2 laboratory will take significantly longer in a BSL-4 setting. This increased time requirement is due to a lot of factors that are aimed at protecting the worker from laboratory-acquired infections. The BSL 4 laboratory should contain a Class III biological safety cabinet but may use a Class I or II BSC in combination with a positive-pressure, air-supplied full-body suit. Usually, BSL 4 laboratories are in separate buildings. Exhaust streams are filtered through high-efficiency particulate air (HEPA) filters, depending on the agents used.
