DeutschNO2 and NOx have implications for acidification of ecosystems and formation of ozone. It is pointed out that synergistic effects are very important and the guideline is given for NOx rather than NO2 alone.
WHO recommended a guideline to protect vegetation as an annual average of 30 µg/m3; for NOx, calculated as the sum of NO and NO2 in ppb and expressed as NO2 in mg/m3.
The annual limit value for the protection of vegetation is 30 µg/m3.
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.
