March 25, 2024 Wei, Y., J. Wu, J. Huang, X. Liu, D. Han, L. An, H. Yu and J. Huang. 2021. Declining oxygen level as an emerging concern to global cities. Environmental Science & Technology 55(12):7808-7817. Home » Wei, Y., J. Wu, J. Huang, X. Liu, D. Han, L. An, H. Yu and J. Huang. 2021. Declining oxygen level as an emerging concern to global cities. Environmental Science & Technology 55(12):7808-7817.