Rapid population growth and urbanisation worldwide accelerate eco-environmental/socio-economic stress as well as adverse climatic and health impacts on urban dwellers. Atmospheric modelling research has largely been performed on a horizontal grid spacing of kilometres or larger due to a lack of understanding of the local-scale phenomena, appropriate parameterisations, and adequate modelling tools, and computer resources. Urban/local street-level air pollution, climate change, and their impacts on population exposure and human health have increasingly received attentions by both researchers and policymakers around the world. Several state-of-the-science models have been recently developed for urban/local street-level air pollution modelling, including the street-network model, the Model of Urban Network of Intersecting Canyons and Highways (MUNICH) that incorporates detailed representations of gas-phase chemistry and secondary aerosol formation pathways, and the Street-in-Grid model (SinG) that dynamically combines a 3-D Eulerian chemical-transport model (CTM), Polair3D, with MUNICH. There have been increasing numbers of developers and users for MUNICH, SinG, and other similar coupled 3-D CTMs and urban canyon models for street-level air pollution modelling worldwide. Recognising the urgent need for scientific advancement, pollution/exposure assessment, policymaking, and public health protection at urban/local-street scales, we launch this special issue to advance scientific understanding of local-scale atmospheric phenomena and promote research and discussion on state-of-the-science urban/local-street-level air quality model development and application for complex interactions among urban air pollution, climate, and health. The special issue is open for all submissions which address the following themes:

• 3-D Street-in-Grid (SinG) model development and application;
• urban canyon/network model development and its incorporation into 3-D CTMs;
• urban/street-level air quality modelling in support of human exposure assessment;
• impact of urban traffic emissions on air quality and human health at a street level.

We launched Part II of the special issue on air quality research at street level. For further information, please visit https://www.atmospheric-chemistry-and-physics.net/articles_and_preprints/scheduled_sis.html