Control pollution in tunnel to protect people health
Particles from engines are mainly less than 1 micron in diameter and have a median diameter of about 0.2 microns, are by far the most dangerous of the commonly found particles.  We are exposed to these at high concentrations every time we travel through an unfiltered urban tunnel. Air Purification stations can protect inside people’s health.

Reduce pollution to the surrounding environment
In recent years, rising environment concerns have led to air purification system being used for purposes upstream of discharge to the atmosphere; the aim is to limit the impact on the external environment. The air purification systems are mostly installed to protect the outside environment. In M30 project, “Tunnel de Sur” executed by CTA, the air after treatment is even better than city’s normal air quality.

Remove mist to increase visibility
The smoke exhausted from cars and trucks will decrease the visibility in tunnel, causing traffic accident. Air purification system can remove 90%-98% of the particles above 0.1μm and keep the visibility within the requirements.

Remove smoke in case of fire incident
Mist and smoke during fire case will prevent people inside from finding the exit and affect rescue. Air purification system can work 20-30 minutes removing smoke that is important for visibility and rescue.

Avoid shaft，easily constructed
Usually the exhaust shaft of the tunnel should be much higher than the surrounding buildings. With air purification system, the exhausted exit can be reduced to only one meter high, to blend into the environment but also saving construction cost.

Reduce airflow in the tunnel and save energy
Usually shaft solution are used to dilute pollution with exit airflow at 25m/s. The air purification system can remove the pollutant and reduce the airflow volume and lower down air speed to 7m/s, which is a huge saving in energy cost for the axial fans.