Is there any aqueous solution (or simple method) to remove trace level of sulfur dioxide/nitrogen monoxide and nitrogen dioxide in a gas stream? I need to generate pure gas from a gas stream which is free of $\ce{SO2}$/$\ce{NO}$/$\ce{NO2}.$ The air is already pretreated by activated carbon and purafil. However, I can't find any solution for removing trace level of this pollutants. I find that many solutions of capturing for large scale like flue gas. However, it is not suitable for trace level (1–10 ppb). 

I know $\ce{O3}$ can react with $\ce{NO}$ to $\ce{NO2}$. However, as I mentioned, I need the gas stream free of $\ce{NO}$ and $\ce{NO2}$ simultaneously. So, converting $\ce{NO}$ to $\ce{NO2}$ is not the answer.
Removal of $\ce{SO2, NO2}$ from solution

As mentioned by Maurice, you can remove $\ce{SO2, NO2}$ by bubbling the mixture bubble through NaOH or KOH solution, or washing it through a column with flowing NaOH or KOH solution at countercurrent.

Removal of $\ce{NO}$ from solution

You can bubble the mixture through $\ce{aq.FeSO4}$ solution.
I remember doing this in eudiometry experiments.