Possibility of Secondary Sub-micron Aerosol Mass Concentrations Forecasting: A Case Study Toward the Possibility of A Future Nowcasting Approach

Particulate Matter (PM) pollution represents a global concern, due to its adverse effect both on environment and on human health. European Envi-ronmental Protection Agency data reveal that one of the most exposed regions is Northern Italy. The attention has been focused on a metropoli-tan city within this area, Torino (NW Italy), and studied the relation between sub-micron particles and their precursor gases under real atmospheric conditions, considering that fine particles have the most relevant adverse health effects. A photolytic computation model developed using an environmental chamber has been adapted and tested for real environmental conditions. The obtained algorithm can constitute the basic building-block for an effective PM1 nowcasting method. Testing it through the use of 2008-2011 summertime data (during the summer the photolytic activity is greater), selected considering only the days with stable fine weather conditions, we found that there is a strong stable dependence between the concentrations of sub-micron particles and its precursor gases, NO in particular. This fact will allow to calculate separately the dependence of PM1 mass concentration values (that represent 65% of PM10) on generation, respect to transport and scavenging phenomena. Finally, this result makes clear that an active policy on NO emission reduction should have effects also on PM pollution in the atmosphere.