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CASE STUDY: Improving Road Tunnel Safety with Airlite Paint - Umberto Tunnel Rome

Posted by Celtic Sustainables on

How Airlite helped to reduce Pollution levels in Rome

When Massimo Bernadoni discovered a concrete based formula that was capable of neutralising polluting molecules in the air, he dreamt of turning it into a product that was accessible enough for anyone to use. For the next few years he worked hard on his discovery and in 2005, came up with a form of paint that was capable of providing not only the same air neutralising properties but also the ability to keep itself clean – Airlite was born.

How it works: When air flows over Airlite paint in the presence of UV light, it generates photocatalytic activity which neutralises many of the pollutants in the air. This, in combination with water molecules in the air, also creates an invisible film on the painted surface which in turn prevents airborne dirt and bacteria from sticking to it, therefore keeping it clean.

As is often the case with new ideas, Bernadoni’s paint was met with lots of scepticism to begin with but undeterred, he pressed on determined to demonstrate its environmental benefits. Finally his persistence payed off and after much discussion and negotiation with the City of Rome, Bernadoni secured agreement to test his Airlite paint in a real environment – the busy Umberto Tunnel.

Built between 1902 and 1905, the Umberto Tunnel connects Piazza di Spagna with the via Nazionale. It was originally built to improve the circulation of traffic in the centre of Rome but over the years, as traffic levels grew, it eventually became known as one of the most polluted places in the capital. 

What a great place to put Airlite to the test!

Umberto Tunnel (before)

Preparing the City Tunnel

In August 2007, renovation work began on the Umberto Tunnel. The old outdated lighting system was removed and the tunnel was cleaned from top to bottom to remove all the soot and grime that had built over the years.

Preparing the Tunnel

Next it was then painted with an initial coat of primer followed by a coat of Airlite paint.

Improving Tunnel Lighting

Finally, a new and improved lighting system was installed to give better visibility to drivers and pedestrians and all importantly, to provide the essential UV light required to activate the photocatalytic properties of the paint. 

Fitting the Tunnel with Improved Lighting

Painting Tunnel with Airlite Air Pollution Reducing Paint

Testing for Air Pollution

The test approach and monitoring strategy were agreed with the Department for Environmental Activities in Rome before it began. 

Testing consisted of taking the following measurements both before and after the tunnels renovation and comparing the resulting data, to evaluate the effects (if any) that Airlite had on the levels of pollution present.

  1. Sensor equipment was installed to measure the levels of NOx pollution (Nitric Oxide (NO) and Nitrogen Dioxide (NO2)) present at each of the tunnel entrances and also in the centre of the tunnel.
  2. Additional influencers on the process such as weather conditions, light levels, volume of traffic and wind speed were also recorded manually.

Monitoring was carried out for a month before renovation (July 3 to July 20, 2007) and again for a month afterwards (Sept 25 to October 10, 2007).

The following points were noted:

  • Due to the specific location of the test (a tunnel) – light conditions were in general assumed to be consistent, although it was accepted that because of it’s large dimensions, it was possible that sunlight at certain times of the day may increase the photocatalytic process.
  • The greatest influence on measurements would be related the amount of traffic (cars per hour) during the test periods and the wind speed.
  • Collection of data at the via del Tritone entrance was likely to be heavily influenced by local traffic, due to the large number of tourist buses being parked there at certain times of the day.

Air Quality Test Results

External pollution levels in Rome increased - the general daily pollution levels (from 8.00hrs -18.00hrs) measured by official fixed stations in the centre of Rome during both testing periods, were found to be higher in the second 3 week period (from September-October 2007), than they were in the first three-week period (July 2007). Figures provided by ARPALazio - the Regional Environmental Agency for the Lazio region, which is monitors pollution levels in Rome. 

The volume of traffic in the tunnel remained consistent during the test period - the average number of vehicles passing through the tunnel during the monitoring periods before and after renovation were found to be the same (approx. 1100 vehicles per hour). 

Light levels in the tunnel remained the same during the test periods – average light levels were found to be consistent both before and after renovation. 

Pollution levels reduced in the tunnel after renovation - NOx levels were found to have reduced consistently following the renovation. The following graph illustrates the NOx levels recorded in the centre of the tunnel (which was considered to be the most representative for evaluation purposes) both before and after renovation. 

Road Tunnel Safety Improved NOx with Airlite Paint

Road Tunnel Safety Improved Instantaneous NOx Peaks after painting with Airlite Paint


  • A 51% reduction in NOx values in the centre of the tunnel was calculated after painting the tunnel with Airlite. 
  • A 25% reduction in NO values in the centre of the tunnel was calculated after painting the tunnel with Airlite. 
  • A clear reduction in pollution peaks was observed after the renovation (pollution peaks are considered very dangerous for the human health).

Further information

Clean Air in Rome: Umberto I Tunnel from Airlite on Vimeo.

Read more about Airlite Paint and the Tunnel on Science Direct: Photocatalytic performances in a city tunnel in Rome: NOx monitoring results (open in  new tab).