Do clothes become naajis (impure) if they brush against something naajis?
Question

The washrooms on board airplanes are very small, and sometimes their walls and floors are visibly naajis. When I go in to do wudoo’, I am not sure whether my clothes have become naajis by brushing against the walls or floor, but I pray anyway, then when I reach my destination I change my clothes and repeat my prayer after the time for that prayer has passed. What is the ruling on this?
Praise be to Allah.Firstly: you have to be certain that the walls of the washroom are naajis. 
Secondly: If you are certain of that, clothes do not become naajis simply by brushing against something, unless the clothes are wet or the walls are wet, which would make the najaasah (impurity) stick to the clothes.  
Thirdly: If you are certain that that has happened, then pray in the naajis clothes. But in this case you have to remove the najaasah itself from the garment, by washing the spot where the impurity is. If you cannot find a clean garment, pray and do not repeat the prayer, because Allah says (interpretation of the meaning):
“So keep your duty to Allah and fear Him as much as you can”
[al-Taghaabun 64:16]