The ventilation system for CWB tunnel is designed as a semi-transverse system with 3 ventilation buildings, namely West Ventilation Building (WVB), Middle Ventilation Building (MVB) and East Ventilation Building (EVB) and East Vent Shaft (EVS) situated at the Eastern Breakwater of the Causeway Bay Typhoon Shelter. Advanced ventilation system will be installed in the tunnel to improve air quality. In case of fire, the system will contain and discharge the smoke inside the tunnel efficiently to ensure the safety of tunnel users. In addition, latest effective air purification system will be set up to clean the air exhausted from the tunnel to a higher standard.