Model simulation of ultrafine particles inside a road tunnel." Atmospheric Environment 37

Various internationally published studies have found a relation between the concentration levels of suspended particulate matter (SPM) and health effects reflected in e g mortality rate, cardiovascular and respiratory deseases. In July 19 of 2001 a new Swedish regulation came into force, regulating the PM10 mass concentrations in ambient air. The most relevant physical parameter – among e g size, area, volume or composition- to characterize SPM effects on health is however under debate. Within heavily trafficed areas there is marked increase of the number of ultrafine (<100 nm) particles, typically with a maximum for a particle diameter of 20-30 nm, but there are also reports of a high peak also for particles <10nm close to roads (Harrison et al, 1999). Taking into account the potential health effect of those ultrafine particles and the fact that they do not contribute significantly to PM10 mass, it is important to investigate their generation, lifetime and general properties. The present work is an attempt to develop a modeling tool for studying the dynamics of different particles sizes in a heavily trafficked urban environment. Aim of the research Simulate the fate of vehicle emitted ultrafine particles inside a road tunnel and, through comparison with field measurements, conclude about their generation, mixing and transformation