Develop and manufacture whole systems for control of air pollution in road tunnels.
Clean Tunnel Air International AS was founded in year 1989, in Trondheim city of Norway. In 2012, CTA established Clean Tunnel Air China Co., in Hong Kong to conduct business in China. In 2020, CTA joined AirQuality Group. For over 30 years CTA has been a world leader in the development and provision of air purification for road tunnels. CTA has finished more than 20 air purification stations in more than 10 tunnels.
Milestone cases
1989: Oslo Festning Tunnel, Norway
One of the world's earliest air purification tunnels
1999: Chinbu Tunnel, South Korea
2 lanes, 2,800 meters long tunnel in Chinbu, South Korea. Installation started in 1998 and finished in 1999. Bypass installation with a total air cleaning volume of 285 m3/s.
2001: Laerdal Tunnel
The world’s longest tunnel equipped with Air Purification System, 24.5 KM
2001: Stromsas Tunnel, Norway
A large axial flow fan of a diameter of 6 meters long was deployed
2007: M30 tunnel, Madrid, Spain
Large shaft air purification system, with a single-station air purification capacity up to 694 m3/s
2021: Central Kowloon Tunnel, Hong Kong
9 APS stations, with an air purification volume of 2,250 m3/s
