Evolution of particulate matter burden in built-up areas of the Marche Region, Italy: a case study

Marche Region is a complex valley-coastal area in central Italy comprising valleys, hills, highly populated areas and industrial districts. During the past fifty years (namely from 1954 to 2010) the built-up area has almost tripled no way proportional to the increase of the resident population (+16%). In the same time span, airborne emissions have dramatically changed. Emissions from industrial facilities decreased due to the use of Best Available Techniques and the deindustrialization while small and/or mobile sources have become the most important players. This led to a significant deterioration of air quality in the cities of the Marche Region, especially due to road traffic and residential heating. For the new types of sources, emission estimate is the only way to assess local impact. The aim of this paper is to understand why the particulate matter concentrations in urban areas of the Marche Region are often above the legal limits, although several emission sources have decreased. To achieve reliable modelling, we applied two very different air quality models: CALPUFF and CAMx. CALPUFF is a non-steady-state puff dispersion modelling system while CAMx is an Eulerian photochemical model, able to estimate both primary and secondary particulate matter. CALPUFF results are useful to evaluate the concentration of primary particulate matter from the main industrial activities, and their contribution related to the total measured in the environmental monitoring unit. These values have been compared with the results of CAMx simulation which considers all the emissions allocated in a regular grid, so it is possible to assess the contribution of non-point sources such as urban traffic, residential heating and natural emissions. Keywords: built-up area, CALPUFF, CAMx, particulate matter.