PTGS2 and long COVID-19: Moreover, activation of Nrf2 stimulated by O3 represses the activity of NF-kB together with the expression of its downstream players IL-6, IL-8, IFN-γ, TNF-α, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS), thus reducing the levels of ROS and RNS, which are among the molecular mechanisms implicated in the systemic and neurological symptoms of PASC [5,127,128].