Volatile organic compounds (VOCs) emission interferes with real-time regulatory monitoring of ozone in urban atmosphere

Abstract

Ozone (O3) pollution is a global concern. The real-time ultraviolet (UV) photometric method is commonly employed at the majority of O3 regulatory monitoring stations around the world. High concentrations of volatile organic compounds (VOCs) have been confirmed to interfere with the real-time O3 monitoring by this method. However, it is unknown whether VOCs emission in the urban environment has an impact on the O3 regulatory monitoring. Here we revealed that high VOCs concentration in an urban industrial zone may result in positive artifacts in O3 measurement at a nearby atmospheric monitoring station. These VOCs were dominated by styrene with concentrations at a mg/m3 level, which was closely related to the abnormally higher O3 measurements observed in this station at night. Experimental validation confirmed that benzene homologues could induce evidently O3 measurement artifacts by the regulatory UV photometric method. By equipped with a temperature control system for the O3 measurement scrubber to desorb VOCs adsorbed by O3 the scrubbing catalyst, the O3 measurement artifacts showed an effective decline with a maximum of 30 ppb in the field cases. This study shed light on the improvement of the air quality assessment by coordination of the monitoring stations and approaches in the future.