With the rapid growth of travel demand and massive investments in transportation infrastructure, large-scale integrated transport hubs that connect multiple transport modes are emerging in many cities. Indoor air pollution in such hubs could have significant adverse impact on passengers’ health due to the high passenger volume and the pivotal role in the transport system. In this study, we examine the distribution and determinants of air pollutant concentrations in large transport hubs using Hongqiao Hub in Shanghai, China as an example. We measure air pollutant concentrations and meteorological factors on 6 days throughout a year in different areas of the hub. We explore the spatial and temporal distribution of air pollutants within the hub and apply General Addictive Models to assess the relationship between air pollution, meteorological factors, and location attributes. We find that motor vehicles including taxis and parking vehicles are a major source of air pollutants in the hub. Based on the research findings, we propose measures to mitigate indoor air pollution in the hub and discuss policy implications.