Targeted Air Pollution Reduction Strategies Using Inventories and Advanced Modelling: Part 2 Airshed Modelling

The relationship between emissions of air pollutants and ground level concentrations can be complex, especially in regions of complex topography and meteorology. The area around the city of Rotorua, New Zealand, is such a place with its location near a large lake, with surrounding hills and spatially variable emissions. The area experiences regular exceedences of the air quality standard for PM10, and the regional council, Environment Bay of Plenty, has to enact measures to eliminate these. In order to be effective the council has used an advanced airshed model to identify which sources contribute to the exceedences, and the quantum of reduction required from each source category. CALMET/CALPUFF modelling has been used along with upper air data input from TAPM. Various emission scenarios have been modelled using extensive regional meteorological input, a newly developed emissions inventory, and on-site monitoring for validation. The results show that the optimum strategy is to achieve a 60% reduction in PM10 emissions from domestic heating, especially wood burners.