The Dispersion of the estimated emissions from the road traffic on the road E18 are calculated with a mathematical atmospheric model called the CAR-FMI (Contaminants in the Air from a Road,Karppinen, 2001; Härkönenym., 2001). The concentrations are calculated only on to the road E18.
The chemical transformation for NO oxidation to NO2 is taken into account in the model to evaluate the actual NO2 concentrations in ambient air. Nitrogen oxides (NOx) emitted in burning of fossil fuels consists from a larger part of nitric oxide (NO, 90–95 %) and from a smaller part of nitrogen dioxide (NO2, 5–10 %). After exhaust from flue the percentage of NO2 in air starts to increase through oxidation of NO mainly by atmospheric ozone (O3).
The full description of the dispersion calculations is under review and will be published during the spring 2020.
The annual concentrations are compared against the WHO air quality standards: World Health Organization (WHO). (2016). Air Pollution:
www9.who.int/airpollution/publications/aqg2005/en/
Sources:
Karppinen, A., 2001. Meteorological pre-processing and atmospheric dispersion modeling of urban air quality and applications in the Helsinki metropolitan area. Academic dissertation. Finnish Meteorological Institute, Contributions No. 33, Helsinki.
Härkönen, J., Nikmo, J., Karppinen, A., and Kukkonen, J., 2001. A refined modelling system for estimating the emissions, dispersion, chemical transformation and dry deposition of traffic-originated pollution from a road. In: Cuvelier, C. et al., Seventh International Conference on Harmo-nisation within Atmospheric Dispersion Modelling for Regulatory Purposes, Joint Research Centre, European Commission, Ispra, Italy, pp. 311-313.
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