New Product Alert – VNOX NO2 and Visibility Monitor

Mon 31 Dec 2012

Tunnel Sensors launch their VNOX Combined NO2 and Visibility Monitor designed specifically for use in tunnels.

Nitrogen dioxide (NO2) is produced as a direct result of engine combustion and is emitted from the tailpipes all types of vehicles. NO2 is toxic and prolonged exposure will have a detrimental effect on human health. Primary tailpipe emissions of NO2 are rising and there is a growing international requirement to measure the level of NO2 in road tunnels.

The Tunnel Sensors VNOX Tunnel Monitor provides a direct optical measurement of nitrogen dioxide (NO2) using differential absorption.

VNOX NO2 & Visibility Monitor for Tunnels

The VNOX sensor consists of a Transmitter (TX) and Receiver (RX) mounted “facing” each other on the wall or ceiling of a tunnel. The TX emits two optical beams; Green and Violet. The NO2 absorbs the Violet light more strongly than the Green and this differential absorption is used to determine the amount of NO2 in the optical path.

The dual wavelength technique means that the VNOX is less sensitive to the effects of drift and false readings due to the presence of dust in the optical beam.

For further information please contact our sales team.

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Vassilis Moustaferis
New Alert ICT Systems, Greece

Tunnel Sensors


The VNOX offers a single sensor
solution for monitoring NO2
and visibility within the tunnel


The LUMIOS MkIII measures the level luminance, or brightness, at tunnel portals to ensure that the visual perception of drivers is maintained, both day and night.


The NOVICOM is a single sensor solution for measuring CO, NO and visibility in road tunnels. An optional NO2 or total NOx reading can also be derived from the NO measurement.