Short Communication Ozone from fireworks: Chemical processes or measurement interference? Zheng Xu a,b , Wei Nie a,b, ⁎, Xuguang Chi a,b , Xin Huang a,b , Longfei Zheng a,b , Zhengning Xu a,b , Jiaping Wang a , Yuning Xie a , Ximeng Qi a , Xinfeng Wang c , Likun Xue c , Aijun Ding a,b a Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, Jiangsu Province, China b Collaborative Innovation Center of Climate Change, Jiangsu Province, China c Environment Research Institute, Shandong University, Ji'nan, Shandong Province, China HIGHLIGHTS • Strong ozone signal was detected in firework plumes using a UV-based analyzer. • Photochemical processes were excluded to explain the observed ozone. • VOCs interference was attributed to the observed ozone signal. • Cardboard was more efficient source than flash powder to emit VOCs inter- ferences. • A signal of 3–8 ppbv O 3 could be de- tected in megacities during Chinese New Year. GRAPHICAL ABSTRACT abstract article info Article history: Received 22 January 2018 Received in revised form 17 March 2018 Accepted 18 March 2018 Available online xxxx Editor: Jianmin Chen Fireworks have been identified as one ozone source by photolyzing NO 2 or O 2 and are believed to potentially be important for the nighttime ozone during firework events. In this study, we conducted both lab and field exper- iments to test two types of fireworks with low and high energy with the goal to distinguish whether the visible ozone signal during firework displays is real. The results suggest that previous understanding of the ozone forma- tion mechanism during fireworks is misunderstood. Ultraviolet ray (UV)-based ozone monitors are interfered by aerosols and some specific VOCs. High-energy fireworks emit high concentrations of particular matters and low VOCs that the artificial ozone can be easily removed by an aerosol filter. Low-energy fireworks emit large amounts of VOCs mostly from the combustion of the cardboard from fireworks that largely interferes with the ozone monitor. Benzene and phenol might be major contributors to the artificial ozone signal. We further checked the nighttime ozone concentration in Jinan and Beijing, China, during Chinese New Year, a period with intense fireworks. A signal of 3–8 ppbv ozone was detected and positively correlated to NO and SO 2 , sug- gesting a considerable influence of these chemicals in interfering with ambient ozone monitoring. © 2018 Elsevier B.V. All rights reserved. Keywords: Fireworks emission Ozone Photochemical reaction Measurement interference 1. Introduction Ozone, as a strong oxidant, is harmful to human health and vegeta- tion and plays a central role in atmospheric chemistry. Troposphere ozone is mainly produced via complex chemical reactions between Science of the Total Environment 633 (2018) 1007–1011 ⁎ Corresponding author at: Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, Jiangsu Province, China. E-mail address: niewei@nju.edu.cn (W. Nie). https://doi.org/10.1016/j.scitotenv.2018.03.203 0048-9697/© 2018 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv