Nitrogen dioxide is a nasty smelling important air pollutant in urban areas and cities. It contributes to the formation of smog and can severely impact human health if exceeding a certain concentration. Major sources of nitrogen dioxide are the burning of fossil fuels, motor vehicle exhaust, petrol and metal refining, electricity generation and other manufacturing industries.

The passive samplers to measure nitrogen dioxide are based on the principle of the NO2 diffusion onto the absorbent triethanolamine. The collected NO2 is then determined spectrophotometrically by the well-established Saltzmann method. Being designed for running without power supply, the samplers are optimized to operate in challenging environments.


Long term sampling

The passive sampler to measure long term, i.e. 1 to 4 weeks, nitrogen dioxide consist of a polypropylene tube and is placed in a special shelter to protect it from meteorological disturbances of all kinds.

Passive sampler and its especially designed protection schelter.




Short term sampling

The passive sampler to measure short term nitrogen dioxide consists of a polypropylene housing with a specific opening of 20 mm in diameter. A glass fiber membrane is attached and supported by a wire net in order to eliminate all kinds of meteorological disturbances.


Passive sampler for the short term measurements.

Nitrogen Oxides NOx

The absorbing medium for the passive NOx sampler contains an oxidant which transforms the NOx molecules into NO2. NOx is expressed as NO2 equivalents. The measurement of NOx is carried with two different samplers: firstly, it is assessed with Triethanolamin and secondly, it is trapped after transforming with an oxidizing agent in the TEA.

The NOx samplers are placed in a designed protective shelter and equipped with membranes to measure near spots with high traffic.

NOx passive sampler.























Specifications: Left: long term Middle: short term Right: NOx (01.01.2016).