Role of sources of NMVOCs in O₃, OH reactivity, and secondary organic aerosol formation over Delhi

Non -methane volatile organic compounds (NMVOCs) play a crucial role in atmospheric chemistry of ozone formation potential (OFP), secondary organic aerosol formation potential (SOAFP), and reactivity of OH ion (LOH). We have estimated LOH, OFP, and SOAFP of 25 ambient NMVOC species measured at the CSIR- National Physical Laboratory, New Delhi from February 2022 to February 2023. Alkenes contributed the highest to the OFP (75.63%) and LOH (68.11%), whereas, aromatics to the SOAFP (81.01%). The source apportionment was performed by positive matrix factorization (PMF) receptor model using the advanced ME -2 engine. Six anthropogenic sources of NMVOCs were identified namely liquified petroleum gas (LPG) + gasoline vehicular emission (GVE), diesel vehicular emission (DVE), painting usage, biomass burning, organic solvent usage, and chemical plant emission respectively. The mixed source (LPG + GVE) is primarily characterized by lower alkanes and aromatics, while DVE is mainly composed of aromatics and higher alkanes. Together, these sources contributed approximately 53% of the total VOCs. Painting usage was dominated by higher alkanes with a contribution of 11.2%, biomass burning is primarily composed of ethane, ethylene, and benzene, contributing 13.54%, and chemical plant emissions are dominated by n -hexane and benzene, contributing 13.78% of the total VOCs. The least contributing source (8.64%) is organic solvent usage, characterized by benzene, isopropyl benzene, and higher alkanes (C9 and C12). Mixed source was the highest contributor to LOH (42.09%), OFP (58.73%), and SOAFP (58.73%). A recent study underscores the importance of prioritizing reactivity -based strategies, focusing on OFP and SOAFP to control NMVOCs and ozone pollution.