Assess learners' ability to analyze major factors influencing urban air quality — including traffic, industry, residential combustion, natural sources, secondary pollutant formation, meteorology, and topography — by interpreting monitoring and emissions-inventory data, applying basic source-apportionment reasoning to estimate relative contributions, considering temporal/spatial variability, and proposing targeted mitigation strategies. Scope: conceptual understanding and data interpretation at a medium difficulty level for environmental/earth studies.