Persistently high oxidative burden of PM2.5 amidst declining mass concentration: Evidence from long-term observation in Shanghai - Yue Huang; Yuankai Xie; Wei Zhang; Lu Xu; Ming Hu; Cheng Huang; Qingyan Fu; Steven J. Campbell; Gang I. Chen; David C. Green; Jialiang Feng; Shunyao Wang (Environmental Pollution, 2026)