The highest concentrations of nitrogen dioxide emissions are found in urban areas and near busy roads, reflecting the contribution of traffic and urban activities to poor air quality.
Ceir y crynodiadau uchaf o allyriadau nitrogen deuocsid mewn ardaloedd trefol a ger ffyrdd prysur, sy’n adlewyrchu cyfraniad traffig a gweithgareddau trefol at ansawdd aer gwael.