Ambient volatile organic compounds at a receptor site in the Pearl River Delta region: Variations, source apportionment and effects on ozone formation

•Ambient VOCs were measured by an online GC-MS/FID system.•Solvent usage, LPG usage and vehicle exhaust are main VOC sources.•The formation of O3 is anthropogenic VOC-limited with dominant contributions from aromatics.•Frequent high-O3 episodes revealed the importance of regional transport in photochemical pollution.