There is rising concern over the significance of Indoor Air Quality (IAQ) as a major contributor to public health issues. The general population has found themselves spending more time indoors due to the recent pandemic related lockdowns and the widespread adoption of remote work. Numerical modelling of IAQ using Computational Fluid Dynamics (CFD) tools is widely being employed. Emissions from vehicular traffic is a major source of indoor air pollution, especially in urban environments. Though significant work has been conducted in this regard, most of the research is focussed on lateral dispersion of the contaminant through the atmosphere. This study seeks to estimate the effect of vehicular traffic source on the variation of IAQ with respect to height, in a multi-storey building using a Reynolds-Averaged Navier Stokes (RANS) model. The external flow through the urban canopy is validated using standard urban canopy models. The validated methodology is then applied to a more realistic multi-storeyed building model with better resolution of the building geometry to include room models. The pollutant concentration reduces with increasing height of the room from the traffic pollution source on the ground. The variation of IAQ due to different indoor ventilation methods is also discussed.