Step 1: Alternate structuring: source-by-source with region example:
Cite Delhi-NCR as the running example: vehicular traffic and industrial emissions provide the year-round base pollution level, while seasonal stubble burning in neighbouring Punjab-Haryana around October-November adds a sharp spike, combined with low winter wind speed trapping the smog close to the ground.
Step 2: Draw out the wider India-level pattern:
This same combination — traffic + industry + biomass/crop burning + weather trapping pollutants — recurs, in varying intensity, across most large Indian cities, making air pollution a nationwide, not just a Delhi-specific, problem.
Step 3: Final Answer:
India's air pollution problem is driven by a combination of vehicular, industrial, and agricultural (stubble) burning sources, intensified in winter by weather conditions that trap pollutants — Delhi-NCR is the most visible example of a much wider national issue.