

Im no chemical engineer from MIT, but I would assume that trace amounts of sodium hydroxide that are readily reacting into sodium bicarbonate well before they make it near the surface of the earth are probably not an issue of concern. Especially considering the acidification caused by traditional exhaust gasses
Considering the long term goal for them is to have them in planes at 30k ft, im sure they are entirely designed with the idea of humidifying the air to an ideal point prior to it getting to the catalyst for the reaction