Reacting NaOH in solution with O3
You could oxidize some hydroxide ions, to wit:

$\ce{OH^- + O3 -&gt; HO2^- + O2}$

Such an oxygen transfer is favored by strongly basic solutions because $\ce{HO2^-}$ is a weaker base ($\mathrm{p}K_\mathrm{a}$ hydrogen peroxide = 11.75) than $\ce{OH^-}$, as well as ozone being a more powerful oxidizer than diatomic oxygen.